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<p>Verification of users’ identities are normally carried out via PIN-codes or ID- cards. Biometric identification, identification of unique body features, offers an alternative solution to these methods. </p><p>Fingerprint scanning is the most common biometric identification method used today. It uses a simple and quick method of identification and has therefore been favored instead of other biometric identification methods such as retina scan or signature verification. </p><p>In this report biometric security systems have been evaluated based on fingerprint scanners. The evaluation method focuses on copies of real fingers, artificial fingers, as intrusion method but it also mentions currently used algorithms for identification and strengths and weaknesses in hardware solutions used. </p><p>The artificial fingers used in the evaluation were made of gelatin, as it resembles the surface of human skin in ways of moisture, electric resistance and texture. Artificial fingers were based on ten subjects whose real fingers and artificial counterpart were tested on three different fingerprint scanners. All scanners tested accepted artificial fingers as substitutes for real fingers. Results varied between users and scanners but the artificial fingers were accepted between about one forth and half of the times. </p><p>Techniques used in image enhancement, minutiae analysis and pattern matching are analyzed. Normalization, binarization, quality markup and low pass filtering are described within image enhancement. In minutiae analysis connectivity numbers, point identification and skeletonization (thinning algorithms) are analyzed. Within pattern matching, direction field analysis and principal component analysis are described. Finally combinations of both minutiae analysis and pattern matching, hybrid models, are mentioned. </p><p>Based on experiments made and analysis of used techniques a recommendation for future use and development of fingerprint scanners is made.</p>

Poly(ADP-ribosyl)ation, a covalent modification of proteins catalyzed by poly(ADP-ribose) polymerases (PARPs), plays a crucial role in regulating DNA repair, DNA replication, and cell death. Poly(ADP-ribose) Polymerase-1 (PARP-1) is a nuclear zinc-finger DNA-binding protein that is the most extensively studied member of the PARP family. The activation of PARP-1 depends on the N-terminal DNA-binding domain, which consists of two unusually long zinc finger-like motifs (termed FI and FII) of the form CX₂CX₂₈/₃₀HX₂C and a newly discovered zinc-ribbon motif (FIII). Though zinc is indispensible for PARP-1 activity, the metal binding affinities of the unusual zinc fingers of PARP-1 is not yet known. In this dissertation, the second zinc finger of PARP-1 was used as a model peptide to study the binding properties of several divalent metal ions (Co²⁺, Cd²⁺, Zn²⁺, and Pb²⁺). Metal-induced protein folding was investigated by circular dichroism, and the effects of the metal ions on PARP-1 activity were investigated by poly(ADP-ribosyl)ation activity assays. This study represents the first detailed biochemical characterization of the PARP zinc fingers. The functional role of each zinc finger in DNA damage recognition is critical for understanding how PARP-1 is involved in DNA repair. Thus, we constructed a series of PARP-1 zinc finger variant proteins and investigated their DNA binding properties and their effects on PARP activity. Using a combination of southwestern blotting and activity assays, we demonstrated that FII is more important for DNA binding, while FI and FIII seem to facilitate PARP activity. The DNA sequence-independent binding properties of PARP-1 were further characterized using DNA probes bearing defined secondary structures. Together, our results indicate that the zinc fingers help position the enzyme at specific DNA damage sites, and also help to activate the catalytic domain upon DNA binding. PARP-1 is involved in caspase-independent apoptosis, and the translocation of apoptosis inducing factor (AIF) out of the mitochondrial matrix has been shown to require PARP-1 activity. However, it is not readily apparent how the catalytic activity of PARP-1 (a nuclear protein) triggers the release of AIF from the mitochondrial matrix. In an attempt to understand the relationship between PARP-1 activity and caspase-independent apoptosis, we demonstrate here that AIF is an in vitro protein substrate for PARP-1. The possible implications of this finding will be discussed. / text

Η μελέτη της πλαστικότητας του ανθρώπινου εγκεφάλου σε όλα τα επίπεδα είναι ένα πολύ σημαντικό βήμα στην εξερεύνηση της λειτουργίας του εγκεφάλου και παίζει πολύ σημαντικό ρόλο στον σχεδιασμό θεραπειών αποκατάστασης μετά από εγκεφαλικές και κινητικές βλάβες. Τα τελευταία είκοσι χρόνια έχει καθιερωθεί πλέον η ιδέα ότι ο ώριμος εγκέφαλος μπορεί να ανακατανέμει τις περιοχές του στην περίπτωση μιας βλάβης ή στην περίπτωση περισσότερης χρήσης ή νέας λειτουργίας, αναδιοργανώνοντας έτσι την λειτουργικότητά του. Και ενώ υπάρχουν αρκετές μελέτες σε ζώα και λιγότερες σε ανθρώπους όπου μελετάται η χωρική έκταση των αλλαγών αυτών, λίγες εργασίες υπάρχουν που να μελετούν τη δυναμική των αλλαγών αυτών σε ένα πεδίο χρόνου μερικών ωρών. Η παρούσα διδακτορική διατριβή συνεισφέρει ακριβώς σε αυτόν τον τομέα: τη μελέτη των πλαστικών αλλαγών σε ένα εύρος χρόνου 6 ωρών με διαδοχικές μαγνητοεγκεφαλογραφικές (ΜΕΓ) μετρήσεις ανά μία ώρα της αναπαράστασης των δακτύλων στον πρωτεύοντα σωματοαισθητικό φλοιό. Μέχρι τώρα στην βιβλιογραφία οι μελέτες για βραχύχρονη πλαστικότητα εστίαζαν στη μελέτη αλλαγών μετά από συγκεκριμένη σωματοαισθητική διέγερση για συγκεκριμένο κάθε φορά χρόνο από μερικά λεπτά και έως τρεις με τέσσερις ώρες. Τα αποτελέσματα των ερευνών αυτών παρουσιάστηκαν διαφορετικά για διαφορετικούς χρόνους μελέτης. Έτσι και για την περίπτωση των δακτύλων στον σωματοαισθητικό φλοιό, μετά από σύντομο χρονικό διάστημα σωματοαιθητικής αλλαγής, η Ευκλείδεια απόσταση μεταξύ των μελετούμενων περιοχών έδειχνε να συρρικνώνεται (Braun et al, 2000; Ziemus et al, 2000) ενώ μετά από περισσότερο χρονικό διάστημα, αυτή να αυξάνεται (Godde et al, 2003; Schaeffer et al, 2004). Η παρούσα μελέτη, συνεισφέρει στην έρευνα της δυναμικής των πλαστικών αλλαγών σε μικρό εύρος χρόνου. Το πρωτόκολλο, είναι εμπνευσμένο από το πρώτο πείραμα πού έδειξε την ύπαρξη πλαστικότητας στον ώριμο εγκέφαλο μέσω της δημιουργίας συνδακτυλίας σε πιθήκους (Allard et al, 1988; 1991). Οι συγγραφείς παρατήρησαν σημαντικές αλλαγές στην αντιπροσώπεση των δύο αυτών δακτύλων στον σωματοαισθητικό φλοιό (Δ3 και Δ4) μετά από 3-7.5 μήνες. Οι δύο περιοχές εμφανίστηκαν ενοποιημένες, και χωρίς την διαχωριστική γραμμή που συνήθως τις διαχωρίζει. Επίσης παρατηρήθηκε η ύπαρξη ιδιοδεκτικών πεδίων που ανταποκρίνονταν στον ερεθισμό και των δύο δακτύλων. Οι συγγραφείς εξέφρασαν αυτό το αποτέλεσμα ως μία ένδειξη του ρόλου του χρονικού συγχρονισμού όπως εκφράζεται και με την αρχή του Hebb για την ομαδοποίηση των εισερχόμενων σημάτων και τον σχηματισμό των ιδιοδεκτικών πεδίων στον φλοιό. Το πρωτόκολλο που χρησιμοποιήθηκε στην παρούσα μελέτη και εμπνευσμένο από το προηγούμενο πείραμα περιλαμβάνει το δέσιμο των δακτύλων του δεξιού χεριού εθελοντών από τον δείκτη (Δ2) έως το μικρό δάκτυλο (Δ5) και τον ξεχωριστό ηλεκτρικό ερεθισμό των Δ2 και Δ5 για τον εντοπισμό της αντιπροσώπευσής τους στον σωματοαισθητικό φλοιό μέσα σε συνολικό χρονικό διάστημα 5.5 ωρών. Οι καταγραφές πραγματοποιήθηκαν με την τεχνική της Μαγνητοεγκεφαλογραφίας, και η ανάλυση έγινε βάσει της μεθόδου της Μαγνητικής Απεικόνισης Πηγών (Μagnetic Source Imaging). H MΕΓ, χάρη της μη αλλοίωσης των μαγνητικών σημάτων από τις ενδιάμεσες δομές του εγκεφάλου χαρίζει καλλίτερο εντοπισμό των ενεργοποιημένων περιοχών. Το κάθε πείραμα αποτελείτο από 7 ΜΕΓ μετρήσεις, με διαλείμματα μεταξύ των μετρήσεων. Η μέση απόσταση μεταξύ των καταγραφών ήταν περίπου 50 λεπτά της ώρας και το κάθε διάλειμμα διαρκούσε μισή ώρα. Η πρώτη καταγραφή έγινε πριν το δέσιμο των δακτύλων. Επίσης καταγραφές της ποσότητας του ηλεκτρικού παλμού (Sensory nerve action potential, SNAP) πάνω στο ωλένιο και μέσο νεύρο γινόταν ταυτόχρονα για την διασφάλιση της σταθερότητας του ηλεκτρικού παλμού που εισέρχεται στο σωματοαισθητικό φλοιό. Δύο πειράματα ελέγχου συμπληρώνουν το πρωτόκολλο, σε μερικούς από τους συμμετέχοντες, ένα με επανάληψη της διαδικασίας χωρίς δέσιμο των δακτύλων μετά από μερικούς μήνες και ένα με συμπληρωματικές ταυτόχρονες μετρήσεις στο άλλο ημισφαίριο. Τέλος η ανατομική μαγνητική τομογραφία, για κάθε συμμετέχοντα λήφθηκε, για επιβεβαίωση του εντοπισμού του ισοδύναμου διπόλου. Μέσω της τεχνικής λοιπόν του ισοδύναμου δίπολου, για κάθε δάκτυλο και κάθε ΜΕΓ καταγραφή κατά την διάρκεια των 5.5 ωρών εντοπίστηκε το ισοδύναμο δίπολο που χαρακτηρίζει το κέντρο βάρους της αντιπροσώπευσης του μεσοποιημένου προκλητού δυναμικού στον πρωτοταγή σωματοαισθητικό φλοιό. Στην συνέχεια ελήφθησαν οι συντεταγμένες του. Μετά την επεξεργασία προ-ανάλυσης του σήματος, μελετήθηκε το ισοδύναμο δίπολο που περιγράφει την κορυφή P30m. Το κύμα P30m προσδιορίζει την είσοδο του ηλεκτρικού σήματος στον σωματοαισθητικό φλοιό. Η θέση του διπόλου κατά τη διάρκεια των μετρήσεων παρουσίασε στατιστικώς σημαντικές αλλαγές, παραμένοντας εντούτοις μέσα στον σωματοαισθητικό φλοιό. Όπως έχει αποδειχθεί και από άλλες μελέτες, στατιστικά σημαντικές αλλαγές στη θέση του ισοδύναμου διπόλου ισοδυναμούν με αλλαγές στην σωματοτοπία (Hodzic et al, 2004; Pleger et al, 2003; 2001). Τα αποτελέσματά λοιπόν έδειξαν ότι συμβαίνουν στατιστικώς σημαντικές αλλαγές στην Ευκλείδεια απόσταση (ΕΑ) των περιοχών μέσα στις 5 περίπου ώρες που διαρκεί η ‘τεχνητή συνδακτυλία’ που επιβάλαμε. Αναλυτικά, και όπως φαίνεται στην Εικόνα 1, στην διάρκεια της πρώτης μισής ώρας, μια μείωση της ΕΑ μεταξύ του δεύτερου (Δ2) και πέμπτου δακτύλου (Δ5) έλαβε χώρα ακολουθούμενη από μία αύξηση της ΕΑ για τις επόμενες δύο ώρες. Στη συνέχεια, ξεκινάει μια μείωση της ΕΑ η οποία διαρκεί πάλι περίπου 2 ωρες. Σημειώνουμε εδώ ότι στα πειράματα ελέγχου, δεν παρατηρήθηκαν αλλαγές στην ΕΑ μεταξύ των δακτύλων, κάτι που μας κάνει να πιστεύουμε ότι η αλλαγές στην ΕΑ οφείλονται αποκλειστικά στην νέα σωματοαισθητική κατάσταση που δημιουργήθηκε με το δέσιμο των δακτύλων. Οι παρατηρούμενες αλλαγές, οι οποίες συμβαίνουν καθ’ όλη τη διάρκεια των έξι ωρών, οδηγούν στο συμπέρασμα ότι συμβαίνει μία συνεχής ανακατανομή (remapping) των περιοχών των δύο δακτύλων στη διάρκεια του χρόνου αυτού. Σημειώνουμε εδώ ότι στα πειράματα ελέγχου, δεν παρατηρήθηκαν αλλαγές στην ΕΑ μεταξύ των δακτύλων, κάτι που μας κάνει να πιστεύουμε ότι οι αλλαγές στην ΕΑ οφείλονται αποκλειστικά στην νέα σωματοαισθητική κατάσταση που δημιουργήθηκε με το δέσιμο των δακτύλων. Επειδή ενδείξεις δεν έχουμε για αλλαγή στην ισχύ του διπόλου συμπεραίνουμε ότι οι αλλαγές αυτές οφείλονται σε μετατόπιση και όχι σε εξάπλωση των αντίστοιχων περιοχών της αντιπροσώπευσης των δακτύλων. Ιδιαίτερο ενδιαφέρον παρουσιάζει το γεγονός ότι οι αλλαγές που παρατηρήσαμε συμβαδίζουν με αλλαγές άλλων ερευνητών στον σωματοαισθητικό φλοιό, ανάλογα με τον χρόνο της παρατήρησης. Δηλαδή, παρόμοιες αλλαγές συμβαίνουν στους αντίστοιχους χρόνους. Αναλυτικά, αύξηση της ΕΑ έχει παρατηρηθεί σε μικρά χρονικά διαστήματα ενώ μείωση της ΕΑ μετά από μεγαλύτερα (της τάξεως των μερικών ωρών) διαστήματα μετά από κάποια σωματοαισθητική αλλαγή/τροποποίηση. Τα αποτελέσματά μας λοιπόν ενοποιούν τα προηγούμενα αποτελέσματα παρουσιάζοντας ένα ενοποιημένο χρονικό πλαίσιο μέσα στο οποίο παρουσιάζονται οι αλλαγές αυτές. Ένα συμπέρασμα που μπορεί να εξαχθεί είναι ότι η ανακατανομή των ιδιοδεκτικών πεδίων των νευρώνων του σωματοαισθητικού φλοιού γίνεται με μη γραμμικό τρόπο. Ο εγκέφαλος προκειμένου να προσδιορίσει τις ομάδες νευρώνων που αναπαριστούν καλλίτερα τη νέα σωματοαισθητική πραγματικότητα ανακαταμερίζει τις δυνάμεις του και επαναπροσδιορίζει τα όριά του. Η αναδιάρθρωση των χαρτών του εγκεφάλου σε τόσο μικρά χρονικά διαστήματα έχει αποδοθεί σε μεταβολή της αναστολής. Το γεγονός ότι οι αλλαγές αυτές στην αναπαράσταση των δακτύλων Δ2 και Δ5 έγιναν τόσο γρήγορα δεν πρέπει να μας εκπλήσσει καθώς μελέτες σε in vivo και in vitro έχουν αποδείξει ότι παρόμοιες αλλαγές στο συναπτικό επίπεδο συμβαίνουν σε χρονικά όρια παρόμοια με αυτά του πειράματός μας, όπως στο LTP και LTD. Επίσης, άλλοι μηχανισμοί όπως αυτοί της ομοιόστασης συμμετέχουν ενεργά σε παρόμοιες περιπτώσεις που έχει παρουσιαστεί πλαστικότητα μετά από αλλαγή στην σωματοαισθητική εμπειρία. Η παρούσα μελέτη εκτός του ότι θέτει ένα χρονικό πλαίσιο μέσα στο οποίο, διαφορετικές αλλαγές στην ΕΑ λαμβάνουν χώρα, αποτελεί μια πρώτη ένδειξη της σημαντικότητας του χρόνου ως παραμέτρου σε ηλεκτροφυσιολογικές μετρήσεις. / The adult primary somatosensory cortex (SI) exhibits a detailed topographic organization of the hand and fingers, which undergoes plastic reorganizational changes following modifications of the sensory input. Although the spatial properties of these changes have been extensively investigated, little is known about their temporal dynamics. The current PhD thesis, contributes exactly to this field: to the study of plastic changes in time frame of 6 hours with consecutive Magnetoencephalographic measurements every hour. The inspiration for the protocol came from the finger webbing paradigm first employed to study adult human representational plasticity. In this paradigm of finger webbing, 4 fingers are temporarily webbed together, hence modifying their sensory feedback, for about 6 hours. We used Magnetoencephalography, a non invasive technique to study magnetic fields of the human brain, in order to measure changes in the hand representation in SI, before, during, and after finger webbing for this time frame of 6 hours. Cortical sources representing the index and little finger were localized using electric current stimulation and with the Equivalent Current Dipole method for all the recording sessions. Our results showed a decrease in the Euclidean distance (ED) between the cortical sources of the index and small finger 30 min after webbing, followed by an increase lasting for about 2 h after webbing, which was followed by a return toward baseline values. These results provide a unique frame in which the different representational changes occur, merging previous findings that were only apparently controversial, in which either increases or decreases in ED were reported after sensory manipulation for relatively long or short duration, respectively. Moreover, these observations further confirm that the mechanisms that underlie cortical reorganization are extremely rapid in their expression and, for the first time, show how brain reorganization occurs over time.

Šio darbo objektas – rankos pirštų įvardijimai lietuvių kalbos tarmėse. Darbo tikslas – parodyti rankos pirštų pavadinimų paplitimą lietuvių kalbos tarmėse. Tikslui pasiekti suformuluoti šie uždaviniai: išsirinkti visus atsakymus į leksikos anketos 111 klausimą (a, b, c, d, e dalys), kaip tarmėse vadinami rankos pirštai, gautus duomenis suklasifikuoti, suklasifikuotų atsakymų pagrindu sudaryti žemėlapius, rodančius atskirų rankos pirštų pavadinimų paplitimą lietuvių kalbos tarmėse, visa tai aprašyti komentaruose ir apibendrinti. Darbo tiriamąją medžiagą sudaro Lietuvių kalbos instituto Kalbos istorijos ir dialektologijos skyriaus Tarmių archyve saugomi atsakymai į leksikos anketos 111 klausimą iš 174 skirtingų gyvenamųjų punktų (vietovių) Lietuvoje ir 4 punktų, esančių už jos ribų. Užrašytų atsakymų pagrindu sudaryti penki atskiri kiekvieno rankos piršto pavadinimų paplitimo lietuvių kalbos tarmėse žemėlapiai. Jiems braižyti buvo naudojama Corel Paint Shop Pro Photo XI programa. Darbo metodai – lingvistinės geografijos, lyginamasis ir aprašomasis. Visoje Lietuvoje ir lietuvių kalbos „salelėse“ už jos ribų vartojamas tas pats pirmojo rankos piršto pavadinimas nykštỹs, kuris tarmėse skiriasi tik kamienu: io (nikštỹs), o (nýkštis, nnkštis) arba ()ē (nýkštė). Keliuose punktuose vartojamas morfologinis pirmojo piršto pavadinimo variantas nykštnis. Pavadinimas nykštỹs ir jo variantai siejami su veiksmažodžiu nỹkti „mažėti“. Labiausiai paplitęs antrojo rankos piršto... [toliau žr. visą tekstą] / The object of the thesis is the names of the fingers in Lithuanian dialects. The aim is to show how far and how often the names are spread in Lithuanian dialects. The aim of the thesis consists of the following tasks: to pick up all the answers to question No. 111 (a, b, c, d, e) from a lexical questionnaire and find out the names of the fingers in Lithuanian dialects; to process and classify data, to make up the maps, indicating the most common areas where they are spread and used in everyday life, to describe and summarize it. The research has been done on the basic material found and stored in the archives of the Lithuanian language institute (in the department of the History and Dialectology of the Lithuanian language). The answers to question No. 111 are from 174 different areas and 4 additional locations beyond the borders of Lithuania The 5 maps of the points where the names of the fingers are spread were made with the help of Corel Paint Shop Pro Photo XI program. The methods used: linguistic geography, comparative, and descriptive. The first finger of the hand is called nykštỹs. This name is the most common all over Lithuania, only in some dialects the stem of the word io may differ, as o (nýkštis, nnkštis) or ()ē (nýkštė). Nykštnis can also be found – it is its morphological variant. Nykštys as the word itself contains the meaning of the verb „disappear“ or „gradually becoming less“. The name smlius for the second finger of a hand is widely spread in Higher... [to full text]

Tyrimo problema: Ilgai trunkanti sėdima padėtis prie kompiuterio, kartu su netinkama darbo vietos ergonomika, yra vienos pagrindinių priežasčių, lemiančių kaulų raumenų sistemos skausmų atsiradimą (Janwantakul et al., 2009). Tačiau, ne visada įmanoma pritaikyti darbo vietą pagal ergonominius principus, tinkančius kiekvienam dirbančiajam, ir, kai nesilaikoma darbo vietos ergonominių principų, darbuotojai dažnai būna priversti prisitaikyti prie prastų darbo sąlygų (Ghosh et al., 2010). Dažniausiai yra rekomenduojama pakeisti darbo pobūdį ar darbo aplinką, arba ieškoti būdų, kaip geriau prisitaikyti, pakeičiant darbo padėtį pagal ergonomikos principus (Voerman et al., 2007). Hipotezė: manome, kad ilgai sėdint įsitempia viršutinės nugaros dalies raumenys ir sąlygoja nervų, įnervuojančių ranką, užspaudimą, dėl ko gali sumažėti plaštakos raumenų jėga, bet fiziškai aktyvių asmenų, nors ir dirbančių sėdimą darbą, plaštakos ir pirštų raumenų jėga turėtų būti didesnė, nei fiziškai neaktyvių asmenų. Tyrimo tikslas: nustatyti sėdimą darbą dirbančių kaklinės stuburo ir viršutinės nugaros dalies skausmų ir fizinio aktyvumo sąsajas su plaštakos ir pirštų jėga. Tyrimo uždaviniai: 1. Nustatyti kaklo ir viršutinės nugaros dalies skausmų paplitimą. 2. Įvertinti sėdimą darbą dirbančių žmonių fizinį aktyvumą. 3. Nustatyti tiriamųjų plaštakos ir pirštų jėgą. 4. Nustatyti koreliacinius ryšius tarp vertintų rodiklių. Tyrimo metodai: buvo apklausiami sėdimą darbą dirbantys asmenys, kurie sėdėdami... [toliau žr. visą tekstą] / The research issue: prolonged sitting position at work using a computer, along with poor workplace ergonomics is one of the main reasons causing development of musculoskeletal pains (Janwantakul et al., 2009). In case of non – compliance with the principles of workplace ergonomic requirements, employees are often forced to adapt to poor working conditions (Ghosh et al., 2010). In most cases, it is recommended to change the nature of the work or the work environment, or to look for ways to better adapt by changing the working position according to ergonomic principles (Voerman et al., 2007). Testing objective: establish the cervical spine and upper back, pain and physical activity correlation with the dominant hand fingers and hand strength for the sedentary job employees. Tasks of the testing: 1. To establish the neck and upper back pain prevalence. 2. To evaluate the physical activity of the persons engaged in sedentary job. 3. To identify the dominant hand palm and fingers strength. 4. To determine the correlation between the estimated parameters. Hypothesis: it is considered that the hand and finger strength is lower of physically inactive individuals or of the persons engaged in sedentary job as they more often have complaints about the neck and upper back pain, than the sedentary workers, but physically active individuals. The following methods applied: the sedentary job employees have been questioned, who spend sitting at least 4 hours a day and they were... [to full text]

The Snail protein functions as a transcriptional regulator to establish early mesodermal cell fate in Drosophila. Later, in germ band-extended embryos, Snail is considered a pan-neural protein based on its extensive expression in neuroblasts. The evidence presented in thesis links snail expression and function in CNS. Cloning and functional characterization of a novel snail homologue, in Drosophila, are also described here. Cloning of this gene, worniu (Chinese for snail), revealed that the neural function of snail is masked by this and another closely related gene escargot. Both Escargot and Worniu contain zinc finger domains that are highly homologous to that of Snail. These three members of Snail protein family are redundantly required for CNS development. Although not affecting formation of neuroblasts, the loss of expression of these three members correlates with disruption of Nb asymmetry and division. Downstream targets of Snail protein family, in these processes, are inscuteable and string. In mutant embryos, which have the three genes deleted, the RNA expression of inscuteable and string is significantly lowered. Consistent with the gene expression defects, the mutant embryos have loss of asymmetric localization of prospero RNA in neuroblasts and nuclear localization of Prospero protein in ganglion mother cells. Transgenic expression of inscuteable and string together, in the snail family deletion mutant, efficiently restores the Prospero expression in GMC, demonstrating that the two genes are key targets of Snail in Nbs. Like in the mesoderm, in CNS Snail function depends on interaction with dCtBP co-repressor. These results suggest that Sna [Snail] family of proteins control both asymmetry and cell division of neuroblasts by activating, perhaps indirectly, the expression of inscuteable and string.

[pt] Altas resistências elétricas em série e baixas resistências em paralelo são fontes de perdas em dispositivos Fotovoltaicos (PV). Em dispositivos que operam sob concentração, esses costumam ser os principais fatores limitantes para o aumento da eficiência de conversão. Excluindo fatores externos associados a falhas no processo de produção, a resistência elétrica em série depende de fatores intrínsecos aos materiais e à estrutura de camadas do dispositivo fotovoltaico. Dessa forma, para minimizar o seu valor é extremamente importante planejar adequadamente esses parâmetros construtivos antes da produção dos dispositivos. Um dos fatores mais impactantes na resistência em série é o desenho da malha de dedos coletores do contato elétrico frontal. Por outro lado, minimizar a resistência em série do contato elétrico requer o aumento da área metálica da superfície frontal, que serve de janela para a radiação solar. Portanto, deve haver um compromisso na redução das perdas elétricas e ópticas. Nesse trabalho, apresentamos os resultados da otimização do desenho da malha de dedos coletores para o contato elétrico frontal para três diferentes geometrias obtidas por algoritmos genéticos. As geometrias escolhidas foram a retangular, tradicional para a produção desse tipo de dispositivo, a hexagonal e a diamante. Além disso, comparamos os resultados obtidos com os de um dispositivo produzido com uma malha otimizada por um método de cálculo analítico. Ao final, discutimos as melhorias introduzidas pelas novas geometrias e apresentamos a configuração otimizada, que foi obtido para uma célula solar de tamanho 5x5 mm com uma estrutura retangular de fingers, com uma redução de perdas de 54,42 por cento que leva a um aumento aproximado de 1,40 por cento em eficiência. / [en] High electrical resistances in series and low resistances in parallel are sources of losses in Photovoltaic (PV) devices. In devices that operate under concentration, these are often the main limiting factors for increasing conversion efficiency. Excluding external factors associated with failures in the production process, the series electrical resistance depends on factors intrinsic to the materials and the layer structure of the photovoltaic device. Thus, to minimize their value it is extremely important to properly plan these constructive parameters prior to the production of the devices. One of the most striking factors in the series resistance is the design of the mesh of collecting fingers of the frontal electrical contact. On the other hand, minimizing the series resistance of the electrical contact requires the increase of the metallic area of the frontal surface, which serves as a window for solar radiation. Therefore, there must be a commitment to reduce electrical and optical losses. In this work, we present the results of the optimization of the design of the mesh of collecting fingers for the frontal electrical contact for three different geometries obtained by genetic algorithms. The geometries chosen were the rectangular, traditional for the production of this type of device, hexagonal and diamond. In addition, we compared the results obtained with those of a device produced with an optimized mesh by an analytical calculation method. At the end, we discussed the improvements introduced by the new geometries and presented the optimized configuration. which was obtained for a solar cell of size 5x5 mm with a rectangular structure of fingers, with a reduction in losses of 54.42 percent that leads to an approximate increase of 1.40 percent in efficiency.

Generation of the primitive neuroectoderm into specialized brain subdivisions, such as the hindbrain primordium, involves the regulated coordination of complex morphogenetic and molecular mechanisms. These processes are evident in the segregation of the zebrafish hindbrain into seven distinct lineage-restricted compartments, termed rhombomeres (r), which are established by the interplay of several spatially-restricted expressed genes. These include transcription factors, members of specific signaling pathways and specialized molecules that mediate cell adhesion and identity. Despite their extensive characterization, it is evident that other genes are involved to mediate the proper specification and segregation of individual rhombomeres. One candidate that likely fits this role is related to the no ocelli/l(2)35Ba gene in Drosophila, termed nlz (nocA-like zinc-finger). Nlz-related proteins behave as transcriptional repressors and are related to the vertebrate Sp1-like family of transcription factors. nlz is dynamically expressed in the zebrafish hindbrain, residing in the caudal hindbrain at gastrula stages and rostrally expanding from presumptive r3/r4 boundary to encompass r3 and r2 at segmentation stages. Nlz localizes to the nucleus and associates with the co-repressors Groucho and histone deacetylases, suggesting that Nlz acts as a repressor. Consistent with this, misexpression of nlz into zebrafish embryos results in a loss of gene expression in the rostral hindbrain (rl-r3). Taken together, the findings in this thesis suggest that Nlz functions as a transcriptional repressor to control segmental gene expression in the rostral hindbrain.

A idade normal para início da puberdade em meninas varia bastante, de 8 a 13 anos, e os genes envolvidos nesse controle são parcialmente conhecidos. Fatores ambientais, como alimentação e exposição a disruptores endócrinos, contribuem para essa variabilidade, de modo que genes modulados epigeneticamente podem justificar parte da complexidade desse processo. O termo epigenética se refere às modificações na expressão gênica que não são causadas por alterações na sequência do DNA. A metilação do DNA é o mecanismo epigenético mais bem estudado. Na última década surgiram evidências demonstrando a relação entre metilação do DNA e desenvolvimento puberal. Em fêmeas de roedores, a hipermetilação do DNA levou à puberdade precoce. Em humanos, a puberdade precoce central (PPC) familial causada por mutações nos genes MKRN3 e DLK1 é considerada um defeito do imprinting, fenômeno epigenético no qual apenas um dos alelos parentais é expresso, estando o outro metilado e inativo. Além disso, um conceito atual propõe que o início da puberdade requer a repressão epigenética de fatores inibidores do eixo gonadotrófico. Recentemente, genes zinc finger (ZNF) foram relacionados ao processo puberal, e muitos deles codificam repressores transcricionais. Neste trabalho, estudamos a metilação do DNA do sangue periférico de 10 pacientes do sexo feminino com PPC familial (casos índices) e 33 meninas com desenvolvimento puberal normal (15 pré-púberes e 18 púberes), usando a plataforma Human Methylation 450 BeadChip. Duas pacientes tinham PPC de causa genética (uma com mutação no MKRN3 e outra com deleção no DLK1) e oito tinham PPC idiopática, sem mutações identificadas pelo sequenciamento exômico global. Cento e vinte regiões diferencialmente metiladas foram identificadas entre as meninas saudáveis pré-púberes e púberes, estando 74% delas no cromossomo X. Apenas uma região mostrou-se hipometilada no grupo púbere e, de maneira importante, contém a região promotora do ZFP57, fator necessário para manutenção do imprinting. Uma vez que a hipermetilação nas regiões promotoras dos genes é relacionada à inibição transcricional, o achado de hipermetilação global do DNA na puberdade sugere que haja inibição de fatores inibidores do eixo gonadotrófico, o que resultaria no início do processo puberal. O receptor estrogênico destacou-se como um fator transcricional que se liga a sete genes diferencialmente metilados entre os controles pré-púberes e púberes. As pacientes com PPC apresentaram mais sítios CpG hipermetilados tanto na comparação com as meninas pré-púberes (81%) quanto púberes (89%). Há doze genes ZNF contendo sítios CpG hipermetilados na PPC. Não foram encontradas anormalidades de metilação nos genes MKRN3 e DLK1 nem em suas regiões regulatórias. Em conclusão, este estudo evidenciou hipermetilação global do DNA em meninas com puberdade normal e precoce, sugerindo que esse padrão é uma marca epigenética da puberdade. Pela primeira vez, mudanças no metiloma de pacientes com PPC foram descritas. Modificações na metilação de vários genes ZNF parecem compor a complexa rede de mecanismos que leva ao início da puberdade humana / Normal puberty initiation varies greatly among girls, from 8 to 13 years, and the genetic basis for its control is partially known. Environmental factors, such as nutrition and exposure to endocrine disruptors, contribute to this variance, and epigenetically modulated genes may justify some of the complexity observed in this process. Epigenetics refers to alterations in gene expression that are not caused by changes in DNA sequence itself. DNA methylation is the best studied epigenetic mechanism. In the last decade, evidence has emerged showing the relationship between DNA methylation and pubertal development. In female mice, DNA hypermethylation led to precocious puberty. In humans, familial central precocious puberty (CPP) caused by mutations in the MKRN3 and DLK1 genes is considered a disorder of imprinting, an epigenetic phenomenon in which only one parental allele is expressed, and the other allele is methylated and inactive. In addition, animal studies indicated that pubertal timing requires epigenetic repression of inhibitory factors of the gonadotrophic axis. Recently, zinc finger genes (ZNF) were related to pubertal development, many of which encode transcriptional repressors. In the present study, we analyzed the DNA methylation of peripheral blood samples from 10 female patients with familial CPP (index cases) and 33 girls with normal pubertal development (15 pre-pubertal and 18 pubertal), using the Human Methylation 450 BeadChip assay. Genetic CPP was diagnosed in two patients (one with a MKRN3 mutation and the other with a DLK1 deletion). The remaining eight cases with idiopathic CPP were previously evaluated by whole exome sequencing and no causative mutations were identified so far. We evidenced 120 differentially methylated regions between pre-pubertal and pubertal healthy girls, and 74% of them were located at the X chromosome. Only one genomic region was hypomethylated in the pubertal group. Of note, it contains the promoter region of ZFP57, an important factor for imprinting maintenance. As DNA hypermethylation in gene promoters is related to gene silencing, the finding of global DNA hypermethylation in puberty suggests inhibition of inhibitory factors of the hypothalamic-pituitary-gonadal axis that results in puberty onset. Importantly, the estrogen receptor was identified as a transcriptional factor that binds to seven differentially methylated genes associated with pubertal process. Patients with CPP exhibited more hypermethylated CpG sites compared to both pre-pubertal (81%) and pubertal (89%) controls. Twelve ZNF genes were recognized as having hypermethylated CpG sites in CPP. The methylation analyses of MKRN3 and DLK1 genes showed no abnormalities. In conclusion, this study revealed a widespread DNA hypermethylation in girls with normal and precocious puberty, suggesting that this pattern can be an epigenetic signature of puberty. For the first time, changes in the methylome of patients with CPP were described. We highlight that alterations in methylation levels of several ZNF genes may impact the onset of human puberty