(1) Evidence is presented that the ''Funnel Canal Organs" described by Luther (1930) are not contact chemoreceptors. (2) Experiments are described which indicate that the Funnel Canal Organ is a mechanoreceptor which responds to strain applied to the cuticle. (3) Histological observations suggest that these sense organs are actually campaniform sensilla which occur both singly and in groups, to form compound sense organs. (4) The relationship between campaniform and chordotonal organs is discussed. (5) Further experiments show that a large variety of chemoreceptor hairs exits. Most are branched and there is a negative correlation between the surface area of the hair (degree of branching) and the amount of irrigation to which the hair is normally subject. (6) The view is expressed that the concert of contact chemoreception is of limited use when considering aquatic Crustacea. The Hair Plate Organs of the chelate pereiopods are suggested as the only chemoreceptor organs in aquatic Decapoda which fulfil a true contact role.

The movements of the eyecups of the common shore crab, Carcinus maenas L., that occur in response to a variety of different visual stimuli, have been studied with a view to analysing the mechanisms of eye movement control in the crustaces. In most experiments, a light flag was glued to one of the crab's eyecups. The flag was orientated so that is partially occluded a beam of light that was focused on a pair of photocells, mounted in opposition to one another. Flag movements thus caused changes in the amount of light reaching the photocells, whose outputs were amplified and displayed on a pen recorder. That small eyecup movements occur in the absence of moving stimuli has been confirmed. These movements have been classified into four categories; tremor - oscillations of peak to peak amplitude 0.01° - 0.2° and predominant frequency 1-3 o.p.s., which could be modified to a small extent by external stimuli; drift - slow wondering movements that mainly occurred when there were no contracts in the visual field; saccades - spontaneous jumps whose frequency and amplitude were extremely variable; and scanning movements of amplitude 0.1° -2.0° peak to peak, and frequency 2-3 o.p.s.; which were always associated with periods of leg waving. All other experiments were directly concerned with the optokinetic responses of Carcinus, which were usually elicited by rotating a black and white striped drum around the crab. Optokinetic nystagnus consists of two phases, a slow forward phase during which the eyes move in the direction of rotation of the stripes, and a fast return phase in which the eyes are flicked back in the opposite direction. Although the evidence is by no means conclusive, it appeared that carcinus has neither a proprioceptive nor a coulometer feedback loop in its eye movement control system. It may thus be unable to distinguish apparent motion, induced by its own eye movement, from world motion. Optokinetic responses also occurred to the movements of a pinlight in an otherwise dark visual field. When recorded in two dimensions on an X-Y plotter, the responses to the movement of a pinlight in a circle were seen to be approximate ellipses, though stepwise movements frequently occurred instead of diagonal movements. The possibility, suggested by this observation, that carcinus resolved diagonal movements into their horizontal and vertical components was confirmed by the finding that the angles of the responses to diagonal movements of the pinlight depended upon the ration of the gains (gain equals response divided by stimulus) to horizontal and vertical pinlight movements. The possibility that carcinus uses this ability to resolve the sun or moon's motion cannot be excluded. When one pinlight was switched off and a similar one was switched on nearby, the crab responded optokinetically, the amplitude of this response being proportional to the stimulus amplitude for apparent movements of up to 3° -4 °. This suggests that movement correlation takes place primarily between closely spaced ommatidia. The responses to the movement or apparent movement of two or more lights were proportional to the shift in the centre of light intensity, an indication that the spatial resolution of the eyes is poor. Optokinetic memory responses, which occur following shifts in the drum position that are not seen by the crab, were also studied. By varying the length of time that the crab viewed the stripes before they were moved, memory was shown to build-up approximately linearly, reaching a plateau representing a gain of between 6 and 30 after 40-100 seconds. The retention of memories allowed to build-up for different periods of time was also examined. There was no evidence for the existence of more than one memory store.

This study reports the development of two important techniques, gene probes and haemocyte cultures that have not been previously available to investigate viral diseases in temperate water marine decapods. These techniques were used to investigate numerous aspects of a reovirus infection of the swimming crab Liocarcinus depurator, P virus, both in vivo and in vitro. The construction and subsequent use of a gene probe has revealed that, not only can virus be experimentally transmitted to L. depurator by injection, but that it is present in natural populations of crabs from the North Sea. Seasonal variation in both incidence of P infection and in incubation time was observed. The incidence of infection increased with increasing temperature whereas incubation time decreased with increasing temperature. In vivo, P virus was found to cause marked haemocytopenia in infected L. depurator and a cytopathic effect, vacuolisation of haemocytes was observed. This effect was not observed in the haemocytes of the shore crab, Carcinus maenas, providing evidence that P virus does not infect this species. To address the lack of techniques for in vitro studies, a cell culture system for crustacean haemocytes was developed. Primary culture of two haemocyte types, hyaline and semi-granular haemocytes was established for haemocytes of both L. depurator and C. maenas. High haemocyte viability was obtained for at least two weeks and, cells retained their functional capabilities in vitro. Having successfully established a haemocyte culture system and the gene probe E2b, it was then possible to begin investigations on P virus infections in vitro. P virus produced a number of effects on haemocytes of L. depurator in vitro. Haemocyte number and haemocyte viability decreased after addition of P virus and a number of cytopathic effects were observed such as necrosis, pycnosis and vacuolisation.

In vitro antibacterial activity in the haemocytes of Carcinus maenas (L) was investigated. Haemocyte lysate supernatants (HLS) were assayed against twelve Gram-positive and Gram-negative marine bacteria, eight of which proved sensitive to the antibacterial factor or factors contained therein. Antibacterial activity was also found in HLS from four other marine crustaceans-Glyptonotus antarcticus, Galathea strigosa, Nephrops norvegicus and Crangon crangon. Activity in C. maenas HLS was independent of divalent cations, operated at high titre, was stable after treatment at 100 °C for 30 minutes and also after three months storage at -70 °C; it was present in the granular cells (which also contain the prophenoloxidase (proPO) activating system, a putative recognition mechanism in arthropods), but was absent from hyaline cells and plasma. In vitro studies were carried out to determine whether a relationship exists between the proPO system and the antibacterial activity in the haemocytes of C. maenas. It was shown that phenoloxidase and an activating serine protease were not responsible for the observed antimicrobial effects, although the possibility that activity resides with some other component of the proPO system has not been excluded. Seasonal variation in antibacterial activity, haemocyte counts and HLS protein concentrations was found, with conspicuous depression of antibacterial activity at two key points in the year. This occurred in conjunction with extremes of water temperature and it is proposed that the variation in antibacterial activity is due to underlying temperature effects on haemocyte counts and protein levels. Low levels of lytic activity against Micrococcus luteus cell walls and low levels of bacterial agglutination were recorded, but the powerful antibacterial activity in HLS could not be attributed to these alone. Gel filtration with Sephadex G-l00 revealed at least three antibacterial proteins of differing molecular size, with estimated MW of 72 kDa, 34 kDa and 4 kDa. The 72 kDa and 34 kDa proteins were bacteriostatic and the 4 kDa protein was bacteriolytic.

No description available.

M.Sc. / At present 35 species of Argulus are recognized in Africa. From a summary of the literature available for Argulus species in Africa it is clear that species descriptions are often the only information available for the majority of species. Information on the anatomy and histology of African Argulus species is even more scant. However, previous literature reveals that the anatomy and histology of the digestive system is similar in most branchiurans. The first study includes a description of a poorly known Argulus species described using SEM. Sixteen male and one female specimen of Argulus personatus Cunnington, 1913, were collected from Bathybates ferox Boulenger, 1898, from Lake Tanganyika in northern Zambia. Results from light and scanning electron microscopy (SEM) examinations documented a thickening of cuticle located on the dorsal surface between the last thoracic segment and abdomen, which was rectangular in shape; the pre-oral spine and the proboscis ornamented with simple scales; a set of 3 large simple setae on the distal end of the basal plate; the dorsal distal end of second podomere of the maxillae ornamented with scales resembling those of a fish; the second and third podomeres of maxillae ornamented with two types of pectinate scales (with fine bristle-like ends and scales with large pointed ends); the ventral distal end of third and fourth maxillary podomeres bearing large teardropshaped scales; a pair of tubular structures present adjacent to the anterior projection; a peg on the fourth pairs of legs of males bearing shallow grooves running irregularly across surface; and an accessory cushion bearing minuteprojections. These characters found in A. personatus were addressed in a redescription. The digestive system of Argulus japonicus metanauplii is described following reconstruction from serial sections. The similarities between the larval and adult digestive system are described. Both digestive systems consist of an oesophagus, oesophageal funnel, anterior midgut, midgut enteral diverticula, posterior midgut and a hindgut. Histologically, the foregut of both the adult and larva consist of cuboidal epithelium and both the adult and larval hindguts are composed of columnar epithelium. Despite the similarities between the adults and larvae some differences exist. Differences include that the epithelium lining of the midgut of newly hatched larvae contain yolk. The midgut diverticula are less ramified than in the adult. The posterior midgut is lined with large swollen cuboidal epithelium with large vacuoles and a ciliated border whereas the adult posterior midgut is lined by large papilliform cells. Argulus japonicus larvae only survive a day after hatching without nutrition from a host and once the first stage larvae start to feed on host tissue they feed mainly on epithelial cells and mucus. There was no blood observed in the lumen of the digestive system. It is concluded from the study that much work remains concerning the taxonomy of African species. Many of the species remains inadequately described and new identification keys must be created. New environmentally safe treatments should be a focus of future development. Also, many physiological aspects of the argulid digestive system remain unknown and provide another focus of future research. / Prof. A. Avenant- Oldewage

No description available.

xiii, 233 leaves : ill. ; 29 cm, Typescript. (Another copy on microfilm is located in Archives) Thesis (Ph.D.)--University of Oregon Includes vita and abstract Bibliography: leaves 220-233 University of Oregon theses, Dept. of Biology, Ph.D., 1978

by Fong Man Kim. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 127-137). / Abstracts in English and Chinese. / Thesis committee --- p.i / Acknowledgements --- p.ii / Abstract --- p.iii / List of figures --- p.viii / List of tables --- p.xi / Abbreviations --- p.xii / Table of contents --- p.xiv / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- LITERATURE REVIEW --- p.3 / Chapter 2.1 --- MIH from Penaeus vannamei --- p.3 / Chapter 2.1.1 --- General Introduction to P. vannamei --- p.3 / Chapter 2.1.1.1 --- Morphology --- p.3 / Chapter 2.1.1.2 --- Geographical distribution --- p.5 / Chapter 2.1.1.3 --- Economic value --- p.5 / Chapter 2.1.2 --- Physiology of Molting in Crustacean --- p.7 / Chapter 2.1.2.1 --- The molt cycle --- p.7 / Chapter 2.1.2.2 --- Physiological effects of ecdysone --- p.8 / Chapter 2.1.2.3 --- Regulation of the secretion of ecdysone --- p.9 / Chapter 2.1.2.4 --- Physiological effects of Molt-inhibiting hormone --- p.10 / Chapter 2.1.3 --- Cloning of MIH cDNA from P. vannamei --- p.14 / Chapter 2.1.3.1 --- Molecular identity of MIH --- p.14 / Chapter 2.1.3.2 --- Cloning of MIH cDNA --- p.15 / Chapter 2.1.3.3 --- Comparison of the cloned MIH-like cDNA with the CHH/MIH/VIH peptide family --- p.16 / Chapter 2.2 --- Plants as Bioreactors --- p.20 / Chapter 2.2.1 --- Principles & Techniques --- p.20 / Chapter 2.2.2 --- Advantages of plant bioreactors --- p.21 / Chapter 2.2.3 --- Tobacco expression system --- p.22 / Chapter 2.2.3.1 --- Tobacco as model plants --- p.22 / Chapter 2.2.3.2 --- Transformation methods --- p.23 / Chapter 2.2.4 --- Phaseolin --- p.26 / Chapter CHAPTER 3 --- EXPRESSION OF MIH IN TRANSGENIC TOBACCO --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Materials & Methods --- p.29 / Chapter 3.2.1 --- Chemicals --- p.29 / Chapter 3.2.2 --- Plant materials --- p.29 / Chapter 3.2.3 --- Bacterial strains and plasmid vectors --- p.30 / Chapter 3.2.4 --- Construction of chimeric genes - --- p.30 / Chapter 3.2.4.1 --- PCR amplification of MIH --- p.30 / Chapter 3.2.4.2 --- Cloning of PCR-amplified MIH into vector pET --- p.31 / Chapter 3.2.4.3 --- Cloning of MIH into vector pBK/Phas-sp and pTZ/Phas --- p.31 / Chapter 3.2.4.4 --- Cloning of MIH into binary vector pBI121 --- p.32 / Chapter 3.2.5 --- Transformation of Agrobacterium with pBI121/Phas-sp-MIH and pBI121 /Phas-MIH by electroporation --- p.39 / Chapter 3.2.6 --- Transformation of tobacco --- p.40 / Chapter 3.2.7 --- Selection of transgenic plants --- p.41 / Chapter 3.2.8 --- GUS assay --- p.42 / Chapter 3.2.9 --- Extraction of leaf genomic DNA --- p.43 / Chapter 3.2.10 --- Extraction of total RNA from developing seeds --- p.44 / Chapter 3.2.11 --- Synthesis of DIG-labeled DNA and RNA probes --- p.45 / Chapter 3.2.12 --- Southern blot analysis of genomic DNA --- p.47 / Chapter 3.2.13 --- Reverse transcriptase - polymerase chain reaction (RT-PCR) --- p.47 / Chapter 3.2.14 --- Northern blot analysis of total RNA --- p.48 / Chapter 3.2.15 --- Protein extraction and tricine-SDS-PAGE --- p.49 / Chapter 3.2.16 --- Purification of 6xHis-tag proteins --- p.50 / Chapter 3.2.17 --- Western blot analysis --- p.50 / Chapter 3.2.18 --- In vitro transcription & translation --- p.52 / Chapter 3.2.18.1 --- Construction of transcription vector containing the chimeric MIH gene --- p.52 / Chapter 3.2.18.2 --- In vitro transcription --- p.56 / Chapter 3.2.18.3 --- In vitro translation --- p.56 / Chapter 3.2.19 --- Particle bombardment --- p.57 / Chapter 3.2.19.1 --- Construction of MIH-GUSN fusion chimeric genes --- p.57 / Chapter 3.2.19.2 --- Conditions of particle bombardment --- p.63 / Chapter 3.2.20 --- Codon modification of MIH gene --- p.63 / Chapter 3.3 --- Results --- p.73 / Chapter 3.3.1 --- Construction of chimeric MIH genes --- p.73 / Chapter 3.3.2 --- "Tobacco transformation, selection and regeneration" --- p.73 / Chapter 3.3.3 --- Detection of GUS activity --- p.74 / Chapter 3.3.4 --- Southern blot analysis --- p.79 / Chapter 3.3.5 --- Detection of MIH transcript in transgenic tobacco --- p.83 / Chapter 3.3.5.1 --- RT-PCR --- p.83 / Chapter 3.3.5.2 --- Northern blot analysis --- p.86 / Chapter 3.3.6 --- Detection of MIH protein by Tricine-SDS-PAGE --- p.86 / Chapter 3.3.7 --- Detection of MIH protein by western blot analysis --- p.88 / Chapter 3.3.7.1 --- Western blot analysis using Anti-MIH antibody --- p.88 / Chapter 3.3.7.2 --- Western blot analysis using Anti-His antibody --- p.90 / Chapter 3.3.7.3 --- Western blot analysis using Anti-MIHA & Anti-MIHB antibodies --- p.90 / Chapter 3.3.8 --- Purification of 6xHis-tag proteins by Ni-NTA column --- p.94 / Chapter 3.3.8.1 --- Western blot analysis of proteins purified by Ni-NTA column --- p.97 / Chapter 3.3.9 --- In vitro transcription and translation --- p.100 / Chapter 3.3.9.1 --- In vitro transcription --- p.100 / Chapter 3.3.9.2 --- In vitro translation --- p.100 / Chapter 3.3.10 --- Particle bombardments --- p.103 / Chapter 3.3.10.1 --- Transient expression of MIH in soybean & tobacco leaves --- p.103 / Chapter CHAPTER 4 --- DISCUSSION --- p.107 / Chapter 4.1 --- Transient expression of MIH genes --- p.109 / Chapter 4.1.1 --- In vitro transcription and translation --- p.109 / Chapter 4.1.2 --- Particle bombardments --- p.220 / Chapter 4.2 --- Post-transcriptional gene silencing (PTGS) --- p.114 / Chapter 4.2.1 --- Post-transcriptional cis-inactivation --- p.114 / Chapter 4.2.2 --- Post-transcriptional trans-inactivation --- p.116 / Chapter 4.2.3 --- MIH gene and PTGS --- p.118 / Chapter 4.3 --- Codon usage --- p.119 / Chapter 4.3.1 --- Codon usage of MIH in plants --- p.120 / Chapter 4.3.2 --- Codon modification of MIH and further study on MIH expression in plants --- p.122 / Chapter 4.4 --- Post-translational protein degradation --- p.123 / Chapter 4.4.1 --- Construction of LRP-MIH fusion proteins --- p.123 / CONCLUSION --- p.125 / REFERENCES --- p.127