When the internal logistics of a company is in a well working condition, the manufacturing process is more efficient and a more efficient material handling process can be developed. A company with the interest of decreasing internal material handling is Scapa Bedding AB, a middle size bed manufacturer situated in Rydaholm, Sweden. Today, Scapa Bedding AB is facing a problem since there is no documentation regarding the material handling, no maps have been developed that displays the internal transports. This thesis attends the question of how to decrease the material handling within the production areas. To construct a solution for the material handling problem tools such as PDCA and DMAIC were used as a foundation in the development of a model that would be applicable on a company of this size. The purpose of the work is to locate and identify the wasteful activities regarding the material handling, and to streamline the activities to reach a minimum of material handling. By extracting data from observations, discussions and interviews the thesis will provide the reader with a problem background and a constructed model the tackle the problem. The model will provide support to locate inefficiencies within the company and in a later stage to develop improvement alternatives relevant to the case. The chosen improvement alternative will in a cost effective way be a solution to the problem. / När den interna logistiken på ett företag är i ett välfungerande tillstånd kan en mer effektiv produktion och materialhanteringsprocess utvecklas. Ett företag som arbetar för att minska på den interna materialhanteringen är Scapa Bedding AB, en medelstor sängtillverkare belägen i Rydaholm, Sverige. Idag står Scapa Bedding inför ett problem då det saknas dokumentation och rutiner på dess befintliga materialhantering. Detta arbete kommer att hantera frågan om hur materialhanteringen inom produktionsarean kan reduceras. För att utveckla en lösning på materialhanteringsproblemen har verktyg som PDCA och DMAIC använts som en grund i utvecklandet av en modell som kan tillämpas på ett medelstort producerande företag. Syftet med detta arbete är att lokalisera och identifiera aktiviteter som bidrar med slöseri inom materialhanteringen samt att effektivisera dessa aktiviteter för att reducera den totala materialhanteringen. Genom att hämta data från observationer, diskussioner och intervjuer kommer detta arbete att erbjuda läsaren en bakgrund på ett problem och en lösning i form av en modell för att lösa det aktuella problemet. Modellen kommer att erbjuda stöd i sökandet efter ineffektiviteter inom företaget för att i ett senare skede utveckla ett kostnadseffektivt förbättringsalternativ.

A series of experiments were conducted to investigate how dietary and ruminal factors regulate urea-N recycling in ruminants. In Experiments 1, 2, and 3, urea-N kinetics were measured using 4-d intra-jugular infusions of [15N15N]-urea. In Experiment 1, the objective was to determine how interactions between dietary ruminally-degradable protein (RDP) level and ruminally-fermentable carbohydrate (RFC) may alter urea-N transfer to the gastrointestinal tract (GIT) and the utilization of this recycled urea-N in rapidly-growing lambs fed high N diets. The dietary factors were: 1) dry-rolled barley (DRB) vs. pelleted barley (PB) as the principal source of RFC; and 2) dietary levels of RDP of 60 vs. 70% (% of CP). Nitrogen intake, fecal and urinary N excretion increased as dietary RDP level increased; however, method of barley processing had no effect on N use. Dietary treatment had no effect on urea-N kinetics; however, endogenous production of urea-N (UER) exceeded N intake. For all diets, 0.669 to 0.742 of UER was recycled to the GIT; however, 0.636 to 0.756 of the GER was returned to the ornithine cycle. In Experiment 2, the objective was to delineate the effects of partial defaunation of the rumen on urea-N kinetics in lambs fed low or high N diets. Treatments were: 1) partial defaunation (PDFAUN) vs. faunation (FAUN); and 2) low (10%, LOW) vs. high (15%, HIGH) dietary CP. Linoleic acid-rich sunflower oil was fed as a partially-defaunating agent. Partial defaunation decreased ruminal NH3-N concentrations. The UER and urinary urea-N excretion (UUE) were lower, and the GER tended to be lower in PDFAUN as compared to FAUN lambs; however, as a proportion of UER, GER was higher and the proportion of recycled urea-N that was utilized for anabolism (i.e., UUA) tended to be higher in PDFAUN lambs. The UER, GER and UUE were higher in lambs fed diet HIGH; however, as a proportion of UER, GER and its anabolic use were higher in lambs fed diet LOW. In Experiment 3, the objective was to delineate how, at similar N intakes, interactions between ruminal partial defaunation and altering dietary RFC may alter urea-N kinetics and N metabolism in lambs. Treatments were: 1) PDFAUN vs. FAUN; and 2) DRB vs. PB. Urinary N excretion was lower and retained N was higher in PDFAUN compared to FAUN lambs. The UER was similar across treatments; however, the GER, expressed as absolute amounts or as a proportion of UER, UUA, and microbial N supply were higher in PDFAUN compared to FAUN lambs. As a proportion of UER, GER was higher, whereas UUE was lower in lambs fed PB compared to those fed DRB. In Experiment 4, the objective was to determine the effects of feeding oscillating dietary CP compared to static dietary CP concentration on N retention and in vitro urea flux across ruminal epithelia. Dietary treatments consisted of a medium CP diet (MEDIUM; 12.8% CP) or diets with oscillating CP content (OSC) fed in two different sequences i.e., 2 d of low CP (9.7% CP) followed by 2 d of high CP (16.1% CP; OSC-HIGH) or vice-versa (OSC-LOW). Ruminal epithelial tissues were collected and mounted in Ussing chambers under short-circuit conditions and the serosal-to-mucosal urea flux (Jsm-urea) was measured using 14C-urea. Although N intake was similar, retained N and microbial N supply were greater in lambs fed the OSC diets compared to those fed the MEDIUM diet. The total Jsm-urea was higher in lambs fed the OSC-LOW compared to those fed the OSC-HIGH diet. Across diets, the addition of phloretin (a known specific inhibitor of facilitative urea transporter-B; UT-B) reduced Jsm-urea; however, phloretin-insensitive Jsm-urea was the predominant route for transepithelial urea transfer. In summary, data presented in this thesis provide new insights that the improved N retention typically observed in defaunated ruminants and in ruminants fed oscillating dietary CP concentrations is partly mediated via increased urea-N recycling to the GIT and utilization of recycled urea-N for anabolic purposes.

Sulfonated phthalocyanines were characterized using capillary electrophoresis and mass spectrometry. Derivatives investigated included the copper, cobalt, zinc and metal-free sulfonated phthalocyanines. The electropherograms of commercially available copper phthalocyanine-3,4',4'',4'''-tetrasulfonic acid and 4,4',4'',4'''-tetrasulfonic acid were very different, consistent with the latter compound having a structure that is not fully sulfonated. Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) were used to characterize the sulfonated phthalocyanines. Mass spectral evidence was obtained for a pentasulfonated species of both the metal-free phthalocyanine and zinc phthalocyanine when these species were made by sulfonation of the metal-free phthalocyanine (followed by zinc insertion in the latter case). Many pathogenic bacteria require heme and obtain it from their environment. Heme transverses the cytoplasmic membrane via an ATP binding cassette (ABC) pathway. Although a number of heme ABC transport systems have been described in pathogenic bacteria, there is as yet little biophysical characterization of the proteins in these systems. The sia (hts) gene cluster encodes a heme ABC transporter in the Gram positive Streptococcus pyogenes. The heme binding protein (HBP) of this transporter is SiaA (HtsA). Several biophysical techniques were used to determine the coordination state, and spin state of both the ferric and ferrous forms of this protein. Identifiers from these techniques suggested that the heme is six-coordinate and low spin in both oxidation states of the protein, with methionine and histidine as axial ligands. The pKa of SiaA was determined, as were the reductive and oxidative midpoint potentials. Guanidinium titration studies of wild-type SiaA showed that the ferric state is less stable than the ferrous state. Free energy of unfolding values [ÄG(H2O)] for the oxidized and reduced proteins were 7.3 ± 0.8 and 16.0 ± 3.6 kcal mol−1, respectively. Denaturation of the histidine mutant H229A was not able to be followed via absorbance spectrometry, possibly due to the large amount of apoprotein present or to non-specific binding of the heme in the binding pocket. The biophysical characterization described herein will significantly advance our understanding of structure-function relationships in HBP.

Detta examensarbete genomfördes våren 2013 på Karlstads universitet där TD Rail & Industry i Västerås stod som uppdragsgivare. Projektet innefattade att kartlägga nuvarande omlastningslösningar av enhetslaster mellan järnvägstransporter och vägtransporter, och utarbeta en konceptuell omlastningslösning med fokus på att öka järnvägstransporternas flexibilitet gentemot vägtransporterna. Där vikten lades på att utarbeta ett välarbetat helhetskoncept. Projektet genomfördes med designprocessen som grund och innehöll bland annat momenten; förstudie, kravspecificering, idégenerering, konceptval m.m. Resultatet blev en vidareutveckling av det redan befintliga systemet CCT som bygger på horisontell överföringsteknik och möjliggör därför omlastning av enhetslaster direkt under kontaktledning. Skillnaden mellan RES och CCT är att man tagit bort ombyggnationen av tågvagn och lastbilschassi, som var en av CCTs stora svagheter, genom två hydrauliska ”teknikplattor”. Tack vare detta tillsammans med sin låga investeringskostnad/driftkostnad öppnar RES nya möjligheter för omlastning på fler strategiska punkter direkt utmed järnvägsnätet och därmed ökar järnvägstransporternas flexibilitet. Som vidareutveckling av RES föreslås ett samarbete med CCT där man initialt utför mer detaljerade beräkningar på teknikplattorna. / This Bachelor of Science thesis was carried out in spring 2013 at Karlstad University for a company called TD Rail and Industry placed in Västerås, Sweden. The project included mapping of current transferring solutions of unit loads between railway and road transports, and the development of a conceptual transferring solution with the focus to increase the flexibility of the railway transport. The importance was to develop a well-made overall concept rather than small detailed parts of it. The project followed the design process methodology and included parts like: pre-study, requirements specification, idea generation, concept selection etc.The result was a further development of an already existing system called CCT based on horizontal transferring technology and therefore allow transferring of units directly under the overhead contact line. Thanks to this, together with its low investment / operating costs RES opens new opportunities for additional strategic transferring places along the railway, thereby increasing the flexibility of rail transports. The difference between RES and CCT is that you no longer need to rebuild the railway cars or the truckchassis , which was one of CCTs major weaknesses, instead the lifting mechanism is replaced by two hydraulic "technique plates". As a further development of the RES a partnership with CCT is proposed.

A series of experiments were conducted to investigate how dietary and ruminal factors regulate urea-N recycling in ruminants. In Experiments 1, 2, and 3, urea-N kinetics were measured using 4-d intra-jugular infusions of [15N15N]-urea. In Experiment 1, the objective was to determine how interactions between dietary ruminally-degradable protein (RDP) level and ruminally-fermentable carbohydrate (RFC) may alter urea-N transfer to the gastrointestinal tract (GIT) and the utilization of this recycled urea-N in rapidly-growing lambs fed high N diets. The dietary factors were: 1) dry-rolled barley (DRB) vs. pelleted barley (PB) as the principal source of RFC; and 2) dietary levels of RDP of 60 vs. 70% (% of CP). Nitrogen intake, fecal and urinary N excretion increased as dietary RDP level increased; however, method of barley processing had no effect on N use. Dietary treatment had no effect on urea-N kinetics; however, endogenous production of urea-N (UER) exceeded N intake. For all diets, 0.669 to 0.742 of UER was recycled to the GIT; however, 0.636 to 0.756 of the GER was returned to the ornithine cycle. In Experiment 2, the objective was to delineate the effects of partial defaunation of the rumen on urea-N kinetics in lambs fed low or high N diets. Treatments were: 1) partial defaunation (PDFAUN) vs. faunation (FAUN); and 2) low (10%, LOW) vs. high (15%, HIGH) dietary CP. Linoleic acid-rich sunflower oil was fed as a partially-defaunating agent. Partial defaunation decreased ruminal NH3-N concentrations. The UER and urinary urea-N excretion (UUE) were lower, and the GER tended to be lower in PDFAUN as compared to FAUN lambs; however, as a proportion of UER, GER was higher and the proportion of recycled urea-N that was utilized for anabolism (i.e., UUA) tended to be higher in PDFAUN lambs. The UER, GER and UUE were higher in lambs fed diet HIGH; however, as a proportion of UER, GER and its anabolic use were higher in lambs fed diet LOW. In Experiment 3, the objective was to delineate how, at similar N intakes, interactions between ruminal partial defaunation and altering dietary RFC may alter urea-N kinetics and N metabolism in lambs. Treatments were: 1) PDFAUN vs. FAUN; and 2) DRB vs. PB. Urinary N excretion was lower and retained N was higher in PDFAUN compared to FAUN lambs. The UER was similar across treatments; however, the GER, expressed as absolute amounts or as a proportion of UER, UUA, and microbial N supply were higher in PDFAUN compared to FAUN lambs. As a proportion of UER, GER was higher, whereas UUE was lower in lambs fed PB compared to those fed DRB. In Experiment 4, the objective was to determine the effects of feeding oscillating dietary CP compared to static dietary CP concentration on N retention and in vitro urea flux across ruminal epithelia. Dietary treatments consisted of a medium CP diet (MEDIUM; 12.8% CP) or diets with oscillating CP content (OSC) fed in two different sequences i.e., 2 d of low CP (9.7% CP) followed by 2 d of high CP (16.1% CP; OSC-HIGH) or vice-versa (OSC-LOW). Ruminal epithelial tissues were collected and mounted in Ussing chambers under short-circuit conditions and the serosal-to-mucosal urea flux (Jsm-urea) was measured using 14C-urea. Although N intake was similar, retained N and microbial N supply were greater in lambs fed the OSC diets compared to those fed the MEDIUM diet. The total Jsm-urea was higher in lambs fed the OSC-LOW compared to those fed the OSC-HIGH diet. Across diets, the addition of phloretin (a known specific inhibitor of facilitative urea transporter-B; UT-B) reduced Jsm-urea; however, phloretin-insensitive Jsm-urea was the predominant route for transepithelial urea transfer. In summary, data presented in this thesis provide new insights that the improved N retention typically observed in defaunated ruminants and in ruminants fed oscillating dietary CP concentrations is partly mediated via increased urea-N recycling to the GIT and utilization of recycled urea-N for anabolic purposes.

The atomic force microscope (AFM) provides a powerful instrument for investigating and manipulating biological samples down to the subnanometer scale. In contrast to other microscopy methods, AFM does not require labeling, staining, nor fixation of samples and allows the specimen to be fully hydrated in buffer solution during the experiments. Moreover, AFM clearly compares in resolution to other techniques. In general, the AFM can be operated in an imaging or a force spectroscopy mode. In the present work, advantage was taken of this versatility to investigate single biomolecules and biomolecular assemblies. A novel approach to investigate the visco-elastic behavior of biomolecules under force was established, using dextran as an example. While a molecule tethered between a solid support and the cantilever tip was stretched at a constant velocity, the thermally driven oscillation of the cantilever was recorded. Analysis of the cantilever Brownian noise provided information about the visco-elastic properties of dextran that corresponded well to parameters obtained by alternative methods. However, the approach presented here was easier to implement and less time-consuming than previously used methods. A computer controlled force-clamp system was set up, circumventing the need for custom built analogue electronics. A commercial PicoForce AFM was extended by two computers which hosted data acquisition hardware. While the first computer recorded data, the second computer drove the AFM bypassing the manufacturer's microscope control software. To do so, a software-based proportional-integral-differential (PID) controller was implemented on the second computer. It allowed the force applied to a molecule to be held constant over time. After tuning of the PID controller, response times obtained using that force-clamp setup were comparable to those of the recently reported analogue systems. The performance of the setup was demonstrated by force-clamp unfolding of a pentameric Ig25 construct and the membrane protein NhaA. In the latter case, short-lived unfolding intermediates that were populated for less than 10 ms, could be revealed. Conventional single-molecule dynamic force spectroscopy was used to unfold the serine:threonine antiporter SteT from Bacillus subtilis, an integral membrane protein. Unfolding force patterns revealed the unfolding barriers stabilizing structural segments of SteT. Ligand binding did not induce new unfolding barriers suggesting that weak interactions with multiple structural segments were involved. In contrast, ligand binding caused changes in the energy landscape of all structural segments, thus turning the protein from a brittle, rigid into a more stable, structurally flexible conformation. Functionally, rigidity in the ligand-free state was thought to facilitate specific ligand binding, while flexibility and increased stability were required for conformational changes associated with substrate translocation. These results support the working model for transmembrane transport proteins that provide alternate access of the binding site to either face of the membrane. Finally, high-resolution imaging was exploited to visualize the extracellular surface of Cx26 gap junction hemichannels (connexons). AFM topographs reveal pH-dependent structural changes of the extracellular connexon surface in presence of HEPES, an aminosulfonate compound. At low pH (< 6.5), connexons showed a narrow and shallow channel entrance, which represented the closed pore. Increasing pH values resulted in a gradual opening of the pore, which was reflected by increasing channel entrance widths and depths. At pH > 7.6 the pore was fully opened and the pore diameter and depth did not increase further. Importantly, coinciding with pore gating a slight rotation of the subunits was observed. In the absence of aminosulfonate compounds, such as HEPES, acidification did not affect pore diameters and depths, retaining the open state. Thus, the intracellular concentration of taurine, a naturally abundant aminosulfonate compound, might be used to tune gap junction sensitivity at low pH.

No description available.

No description available.

Introduction. Plusieurs maladies neurodégénératives bénéficieraient de meilleures ap-proches diagnostiques, dont la maladie d’Alzheimer. Celle-ci affecte en particulier les systèmes cholinergiques du SNC, et de nombreuses études d’imagerie ont tenté d’évaluer la dégénérescence de ce système à des fins diagnostiques, à l’aide de ligands radioactifs de diverses composantes du système ACh. En définitive, la plupart de ces études ne se sont pas montrées satisfaisantes. À la recherche de meilleures approches dans ce domaine, nous avons décidé d’évaluer les possibilités offertes par le (-)-[18F]Fluoroethoxy-benzovesamicol ((-)-[18F]FEOBV), un agent émetteur de positons se liant au VAChT de façon spécifique et réversible. Avant d’en arriver à une utilisation humaine cependant, une validation animale en plusieurs étapes s’avère nécessaire, mais celle-ci nous est apparue justifiée à la lumière de résultats d’études préliminaires en TEP chez le rat, qui se sont montrées très prometteuses. Nous nous sommes donc attaqués à la caractérisation du métabolisme de cet agent. Ceci a exigé, dans un premier temps, la mise au point d’une méthode chromatographique d’analyse des métabolites sanguins et, dans un deuxième temps, l’évaluation de ces métabolites et de leur cinétique chez le rat. Ces données permettront ultérieurement, chez l’humain, de procéder à des études quantitatives en TEP. Étude #1: Une fois les paramètres chromatographiques optimisés, le TR du (–)-FEOBV fut établi à 7.92 ± 0.18 minutes. Étude #2 : Le métabolisme in vivo s’est montré très rapide et temporellement variable, mais un seul métabolite hydrophile a été identifié. La fonction d’apport au cerveau du (–)-[18F]FEOBV a pu être établie après correction pour la présence du métabolite détecté. Conclusion. Dans l’ensemble, le (–)-[18F]FEOBV semble très prometteur en tant que marqueur biologique du système cholinergique pré-synaptique. / Background. Several neurodegenerative diseases would benefit from better diagnostic tools, and Alzheimer’s disease is an obvious point in case. Of interest, that disease par-ticularly affects CNS cholinergic systems. Many studies have evaluated neurodegenera-tion in that system during the course of Alzheimer’s disease, some using imaging tech-niques with radioactive ligands targeting the cholinergic system. However, most of those studies have shown rather unsatisfying results. Therefore, our team has decided to evaluate a so far never used in primates positron emitting ligand of the VAChT which reversibly binds to its target, (-)-[18F]Fluoroethoxy-benzovesamicol ((-)-[18F]FEOBV). Of course, before being able to use this ligand in a clinical setting, a multi-step animal validation needs to be performed. As initial experiments with PET imaging yielded encouraging results, assessing the metabolism of (-)-[18F]FEOBV was the next logical step. First, an HPLC methodology had to be developed to analyse blood metabolites. Then, we were able to use that methodology to analyse metabolites and their kinetics in the rat. That data will allow quantitative studies in humans with PET. Study #1: After the chromatographic parameters had been optimised, the TR of (–)-FEOBV was established at 7.92 ± 0.18 minutes. Study#2 In vivo metabolism was found to be fairly rapid and somewhat temporally variable, but a lone hydrophilic metabolite was identified. The plasmatic input function was obtained and corrected for metabolism. Conclusion. Overall, (–)-[18F]FEOBV holds promise as a potential ACh system pre-synaptic marker.

Le testicule assure la production des spermatozoïdes et la sécrétion de la testostérone. Chaque fonction est assumée par un compartiment cellulaire distinct: l’épithélium séminifère et le tissu interstitiel. Le cholestérol, présent dans les deux compartiments, est un composé indispensable aux membranes cellulaires et un précurseur essentiel de la testostérone. Dans le compartiment interstitiel, environ 40 % du cholestérol utilisé pour la production hormonale est importé du sang à partir des lipoprotéines HDL et/ou LDL. Dans l’épithélium séminifère, la cellule de Sertoli assure le contrôle et le maintien de la spermatogenèse. Elle a la capacité de synthétiser du cholestérol à partir de l’acétate in vitro, néanmoins, il n’y a pas d’évidence qu’elle le fait in vivo. De plus il existe, au niveau des tubules séminifères, une barrière hémato-testiculaire qui empêche le libre passage de plusieurs composés sanguins, y compris le cholestérol. Nous avons testé l’hypothèse qu’il existe des moyens d’importation du cholestérol sanguin, mais aussi l’exportation du cholestérol intra-tissulaire, qui contourneraient cette barrière et qui contribueraient au maintien du taux intratubulaire du cholestérol compatible avec le bon déroulement de la spermatogenèse. Nous avons comparé les taux de variation de l’expression de l’ARNm et de la protéine des transporteurs sélectifs de cholestérol SR-BI, SR-BII, CD36 et ABCA1 aux taux de variation du cholestérol libre et estérifié au cours de la spermatogenèse chez les souris normales durant le développement postnatal. Afin de mieux apprécier le niveau d’implication de chacun de ces récepteurs, nous avons examiné comment la suppression du gène d’une enzyme comme la lypase hormono-sensible (HSL) ou de celui d’un transporteur de cholestérol comme SR-BI, CD36 ou NPC1 était compensée et comment cette suppression affectait le taux de cholestérol libre et estérifié dans chacun des deux compartiments cellulaires du testicule. Nous avons dans un premier temps mis au point une nouvelle technique d’isolation des testicules en fraction enrichie en tissu interstitiel (ITf) et en tubules séminifères (STf) qui a l’avantage de mieux préserver l’intégrité des formes phosphorylées et glycosylées des protéines comparée aux techniques préexistantes. Les résultats de nos analyses ont montré que l’expression de SR-BI et CD36 étaient maximales dans les ITf au moment où les souris ont complété leur maturité sexuelle et où le niveau de synthèse de la testostérone était maximal. Dans les tubules séminifères, l’expression maximale de SR-BI et le taux le plus élevé de cholestérol estérifié étaient mesurés de façon concomitante à 35 jours après la naissance, au moment où la première vague de l’activité spermatogénétique était complétée. L’expression de l’ABCA1 était maximale au moment où le taux de cholestérol était élevé et minimale au moment où le taux de cholestérol était le plus bas, alors que le niveau d’expression de CD36 était maximal chez l’adulte au moment où le taux de spermiation était le plus élevé. L’expression de SR-BII variait peu dans les deux compartiments cellulaires durant le développement. La suppression génétique de la HSL et de NPC1, qui cause une infertilité chez les souris mâles, était accompagnée d’une accumulation de cholestérol libre et estérifié dans les tubules séminifères. Par contre, la suppression génétique de SR-BI et CD36, qui ne causent pas d’infertilité chez les souris mâles était sans impact significatif sur le taux de cholestérol intratubulaire. Nous avons montré que l’invalidation génétique d’un transporteur sélectif ou d’une enzyme du métabolisme du cholestérol était accompagnée d’un ensemble de mécanismes de compensation visant à maintenir le taux de cholestérol libre aux niveaux semblables à ceux mesurés dans les fractions tissulaires de souris normales. Ensemble, nos résultats ont montré que l’expression des transporteurs sélectifs de cholestérol SR-BI, SR-BII, CD36 et ABCA1 variait en fonction de la spermatogenèse et du taux intratesticulaire du cholestérol suggérant leur contribution au maintien de l’homéostasie du cholestérol intratesticulaire. / The testis is made up of loops of convoluted seminiferous tubules surrounded by interstitial tissue composed of loose connective tissue containing Leydig cells that secrete testosterone into the bloodstream. The seminiferous tubules are lined with a stratified epithelium containing germ cells at various stages of development and the supporting Sertoli cells. Cholesterol is present in both compartments and is crucial for the development of germ cells, the fertility of spermatozoa as well as for testosterone production. In the interstitial compartment, approximately 40 % of the cholesterol used for the hormonal production is imported from blood lipoproteins HDL and LDL. In the seminiferous epithelium, Sertoli cells plays key role in the development and maintenance of spermatogenesis. Sertoli cells have the capacity to synthesize cholesterol from acetate in vitro, however, there is no evidence that they do so in vivo. In addition, there is a blood-testis barrier within the seminiferous tubules that prevents the free passage of several blood compounds including cholesterol. We tested the hypothesis that there are ways of blood cholesterol uptake, but also the intratubular cholesterol efflux that by-pass this barrier and contribute to the cholesterol homeostasis within the tubules. We compared expression patterns of the mRNA and proteins for selective cholesterol transporters SR-BI, SR-BII, CD36 and ABCA1 with those of free and esterified cholesterol during the spermatogenesis in normal mice during the postnatal development. To better appreciate the level of involvement of each receptor, we examined the effect of the deletion of the genes for an enzyme (HSL) or for cholesterol transporters (SR-BI, CD36 or NPC1) on the rate of free and esterified cholesterol in both compartments of the testis. At first, we worked out a new technique to separate the testes into interstitial tissue- (ITf) and seminiferous tubule-enriched fractions (STf) that has the advantage of allowing a more faithful detection of the phosphorylated and glycosylated forms of the proteins compared to existing techniques. Our results showed that the expression of SR-BI and CD36 was maximum in the ITf when mice completed their sexual maturity and reached the peak level of testosterone synthesis. In the seminiferous tubule-enriched fractions, the maximum level of SR-BI expression coincided with the highest level of esterified cholesterol during the development at 35 days, as the first wave of the spermatogenetic activity was completed. ABCA1 reached the highest expression level when cholesterol was high and reached the lowest when cholesterol was at its minimum, while the level of CD36 expression was maximal in the adult tubules as the rate of spermiation was the highest. The knockout of the HSL and NPC1, which renders the male mice infertile, was accompanied by the accumulation of free and esterified cholesterol in the seminiferous tubules. On the other hand, the knockout of SR-BI and CD36, linkes to infertility, did not affect the rate of intratubular cholesterol. Here we showed that genetic withdrawal of a cholesterol transporter or of an enzyme involved in cholesterol metabolism was compensated by other transporters or enzymes in order to maintain the level of free cholesterol similar to those measured in the tissue-enriched fractions of wild-type mice. Together, our results showed that the expression of the selective cholesterol transporters SR-BI, SR-BII, CD36 and ABCA1 varied according to the spermatogenesis and intratesticular cholesterol rate, thus suggesting their contribution to the preservation of the intratesticular cholesterol homeostasis.