A study of the polycomb group complexes in the maintenance of heterochromatic genome stability and Alzheimer's disease.

La démence d'Alzheimer est une maladie neurodégénérative caractérisée par une perte progressive et irreversible des fonctions cognitives et des compétences intellectuelles. La maladie d’Alzheimer se présente sous deux formes: la forme familiale ou précoce (EOAD) qui représente 5% des cas et elle est liée à des mutations génétiques affectant le métabolisme des peptides amyloïde; et la forme tardive ou sporadique (LOAD) qui représente 95% des cas mais son étiologie est encore mal définie. Cependant, le vieillissement reste le principal facteur de risque pour développer LOAD. Les changements épigénétiques impliquant des modifications des histones jouent un rôle crucial dans les maladies neurodégénératives et le vieillissement lié à l'âge. Des données récentes ont décrit LOAD comme un désordre de l'épigénome et ont associé ce trouble à l'instabilité génomique. Les protéines Polycomb sont des modificateurs épigénétiques qui induisent le remodelage de la chromatine et la répression des gènes à l'hétérochromatine facultative. Nous rapportons que les souris hétérozygotes pour une protéine Polycomb développent avec l'âge un trouble neurologique ressemblant à LOAD caractérisé par l’altération des fonctions cognitives, la phosphorylation de la protéine tau, l'accumulation des peptides amyloïde, et le dysfonctionnement synaptique. Ce phénotype pathologique est précédé par la décondensation de l’hétérochromatine neuronale et l'activation de la réponse aux dommages à l'ADN. Parallèlement, une réduction d’expression de polycomb, malformations de l'hétérochromatine neuronale, et l'accumulation de dommages à l'ADN étaient également présents dans les cerveaux de patients LOAD. Remarquablement, les dommages de l'ADN ne sont pas distribués de façon aléatoire sur le génome mais sont enrichis au niveau des séquences répétitives. Les conclusions présentées dans cette thèse ont identifié des modifications épigénétiques spécifiques qui conduisent à une instabilité génomique aberrante menant à la formation de LOAD. Ces résultats vont aider au développement de nouveaux traitements qui peuvent potentiellement ralentir la neurodégénérescence.

Development of Cell Culture Systems from Selected Species of Fish and Prawns

The present work deals with the development of primary cell culture and diploid cell lines from two fishes, such as Poecilia reticulata and Clarias gariepinus. The greatest difficulty experienced was the avoidance of bacterial and fungi contamination. Three types of cell cultures are commonly developed, primary cell culture, diploid cell lines and heteroploid cell lines. Primary cell culture obtained from the animal tissues that have been cultivated in vitro for the first time. They are characterized by the same chromosome number as parent tissue, cultivated in vitro for the first time, have wide range of virus susceptibility, usually not malignant, six chromatin retarded and do not grow as suspension cultures. Diploid cell lines arise from a primary cell culture at the time of subculturing. Diploid cell lines commercially used in virology are W1-38 (human embryonic lung), W1-26 (human embryonic lung) and HEX (Human embryonic kidney). Heteroploid cell lines have been subcultivated with less than 75% of the cells in the population having a diploid chromosome constitution. Tissue cultures have been extensively used in biomedical research. The main applications are in three areas, Karyological studies, Identification and study of hereditary metabolic disorders and Somatic cell genetics. Other applications are in virology and host-parasite relationships. In this study an attempt was made to preserve the ovarian tissue at low temperature in the presence of cryoprotectants so that the tissue can be retrieved at any time and a cell culture could be developed.

Effects of Thermal Modifications on the Rheological Characteristics and Protein Quality of Three Species of Fish of Varying Collagen Content

School of Industrial Fisheries, Cochin University of Science and Technology

Influence of collagen content on the texture andstorage quality of fish mince basedproducts

Objectives of the present study are to find out the proximate composition of 20 commercially important tropical fish species on the west coast of India. To determine the collagen content in these commercially important fish species and fractionation of collagen into acid soluble collagen (ASC) and hot water soluble (insoluble) collagen (ISC). To classify fishes according to its collagen content and To study the different storage characteristics in the mince based product—surimi, from different species of fishes. The researcher tries to find out a suitable collagen source to incorporate in surimi. and studies the different storage qualities in the mince based product, surimi at different levels of collagen in different species of fishes. The optimum collagen level to get desirable texture and storage quality for mince based product. The researcher aims to develop some products from surimi with desirable level of collagen. And compare the products prepared from surimi of lesser collagen content fish containing desirable level of collagen with surimi prepared with high collagen content fish without collagen. This study gains in importance as there is littleinformation on the collagen content of different species of fishes in India. So far no attempt was made to classify fishes according to its collagen content.

Studies on the distribution and abundance of fish eggs and larvae off the south—west coast of India with special reference to scombroids

The broad objective of the present study is to present a synoptic picture of the distribution and abundance of fish eggs and the lmportant groups of fish larvae obtained off the SW coast of India. so as to delineate the spawning areas and seasones of the fish population. with special reference to the scombroid fishes. An attempt was also made to correlate the occurrence of certain categories of larvae and hydrographical factors like temperature and salinity. The present effort was a pioneering one in Indian waters. in as much as it involved systematic and seasonally repetitive collection of ichthyoplankton from a large stretch of our seas and mapping of their distribution and abudance.

Studies on coagulase-positive staphylococci and Vibrio parahaemollticus in selected items of fish, crustaceans and fishery products

In India much work has been done on different aspects of quality of processed fish and fishery products (Pillai et al., 1965; Iyer and Chaudhuri, 1966; Iyer et al., 1966; Sreenivasan and Joseph, 1966; Pillai and Rao, 1969; Mathen et al., 1975; Valsan et al., 1985) and standards have been formulated for almost all the fishery products. Quality standards for fresh fish cover only a few fish species available in the markets. For the formulation and recommendation of quality standards for fish and fishery products for domestic trade detailed background informations are necessary. Khot et al., (1982), Valsan et al. J (1985) and Iyer et al. (1986) have reported on the bacterial flora of sea foods at retail level in Bombay. Cochin is a major fish landing centre of the south west coast of India, and an average of 25,000. tonnes of fish/shell fish are landed annually at this harbour which is about 10 percent of the total catch of fish in Kerala (Lakshmanan -et -al., 1984). All the varieties of marine, brackish water and fresh water fishes are available in Cochln throughout the year for catering to Its cosmopolitan. population and informations regarding their bacteriological quality are scanty. Hence the present study was undertaken to investigate the bacteriological quality of fish and fishery products available in the markets and cold storages situated in and around Cochin meant for internal consumption.

Enzyme reactions as index of freshness of Fish and Shellfish

An attempt has been made in this study to screen some fish muscle enzymes to assess their potential worth in testing the degree of freshness of fish. A problem with routine enzyme activity determinations is the complexity of the method of enzyme assay. Hence, in the present study as far as possible simple assay techniques were adopted. Several species were screened to assess the possibility of employing this procedure on a large scale. It is hoped that findings of this study will lead to the development of meaningful criteria in testing the freshness of fish. This thesis has been divided into five chapters

“Stress Responses of Stinging Catfish Heteropneustes fassilis (Bloch) to Organophosphorus Insecticide Monocrotophos”

Poisoning by pesticides from agricultural fields is a serious water pollution problem and its environmental long-term effect may result in the incidence of poisoning of fish and other aquatic life forms (jyothi and Narayan, 1999). Fishes like Heteropneustesfbssilis and C/arius batrac/nus are especially prone to serious pesticide pollution as their habitat is mostly the agriculture area. Though only few studies are conducted in this area, it can be assessed from the local information that, population of such fish is on the verge of vulnerability due to extensive use of pesticides. The knowledge of sublethal effects of xenobiotic compounds on hematological parameters, enzyme activities and metabolite concentrations is very important to delineate the fish health status and provide a future understanding of ecological impacts. These pesticides act by causing inhibition of cholinesterase enzymes (ChE) by formation of enzyme inhibitor complex (O'Brien, 1976) and damaging the nervous system. These effects may result in metabolic disorders. Associated to cholinesterase activities, a study of other enzymes such as phosphatases and aminotransferases close to intermediary metabolite determination provides a wider view of metabolism. Interest in toxicological aspects has grown in recent years and research is now increasingly focused on mechanistic aspects of oxidative damage and cellular responses in biological system. The term ‘biomarker’ is generally used in a broad sense to include almost any measurement reflecting an interaction between a biological system and a potential hazard, which may be chemical, physical or biological (WHO, 1993). As biomarker stands for immediate responses, they are used as early warning signals of biological effects caused by environmental pollutants. The present work attempts to assess the toxicity of organophosphorus insecticide monocrotophos on the experimental organism selected for this study namely stinging catfish (Heteropneustesfossi/is) (Bloch), and to probe into the stress responses of the organism

Temporal pattern of fish production in a microtidal tropical estuary in the south-west coast of India

The status of fisheries and seasonal variation in fish diversity in the Kodungallur-Azhikode Estuary (KAE) were investigated. Total annual average fish production in the estuary declined significantly to 908.6 t with average yield of 5.4 kg ha-1 day-1, when compared to earlier study; where 2747 t was reported. During the present study, 60 species of finfishes (belonging to 34 finfish families), 6 species of penaeid shrimps, 2 species of palaemonid prawns, 2 species of crabs (4 crustacean families), 6 species of bivalves and 2 species of edible oysters (3 molluscan families) were noticed. Finfishes were the major group that contributed 69.62% of total fishery in the estuary and crustaceans (23.47%), bivalves (6.84%) and oysters (0.07%) also formed good fishery. Many of the fish species in the estuary were observed as threatened (Horabagrus brachysoma, Channa striatus, Channa marulius, Clarias batrachus, Heteropneustes fossilis and Wallago attu). The major fishing gears employed in the estuary were gillnets, cast nets, stake nets, scoop nets, ring nets, traps and Chinese dip nets. Gillnets contributed 45% of the total fish catch. Gillnets also showed highest catch per unit effort (CPUE) of 6.91 kg h -1 followed by cast nets (1.85 kg h -1), Chinese dip nets (3.20 kg h -1), stake nets (3.05 kg h -1), ring nets (1.27 kg h -1), hooks and lines (1.35 kg h -1) and scoop nets (0.92 kg h -1). The study implies that temporal changes in fish landing pattern of the KAE was mainly due to environmental variability, habitat modification and fish migration; under the influence of south-west monsoon and anthropogenic activities in the KAE. Results of the study suggest that spatio-temporal variations in the fish community structure could be an indicator for anthropogenic stress and it should be considered for restoration programmes.

On-the-Fly Maintenance of Series-Parallel Relationships in Fork-Join Multithreaded Programs

A key capability of data-race detectors is to determine whether one thread executes logically in parallel with another or whether the threads must operate in series. This paper provides two algorithms, one serial and one parallel, to maintain series-parallel (SP) relationships "on the fly" for fork-join multithreaded programs. The serial SP-order algorithm runs in O(1) amortized time per operation. In contrast, the previously best algorithm requires a time per operation that is proportional to Tarjan’s functional inverse of Ackermann’s function. SP-order employs an order-maintenance data structure that allows us to implement a more efficient "English-Hebrew" labeling scheme than was used in earlier race detectors, which immediately yields an improved determinacy-race detector. In particular, any fork-join program running in T₁ time on a single processor can be checked on the fly for determinacy races in O(T₁) time. Corresponding improved bounds can also be obtained for more sophisticated data-race detectors, for example, those that use locks. By combining SP-order with Feng and Leiserson’s serial SP-bags algorithm, we obtain a parallel SP-maintenance algorithm, called SP-hybrid. Suppose that a fork-join program has n threads, T₁ work, and a critical-path length of T[subscript ∞]. When executed on P processors, we prove that SP-hybrid runs in O((T₁/P + PT[subscript ∞]) lg n) expected time. To understand this bound, consider that the original program obtains linear speed-up over a 1-processor execution when P = O(T₁/T[subscript ∞]). In contrast, SP-hybrid obtains linear speed-up when P = O(√T₁/T[subscript ∞]), but the work is increased by a factor of O(lg n).

Intraovarian sperm storage in Helicolenus dactylopterus dactylopterus fertilitzation, crypt formation and maintenance of stored sperm

The females of the bluemouth rockfish, Helicolenus dactylopterus dactylopterus (DelaRoche, 1809), store sperm within their ovaries for periods of up to 10 months. Twenty six females with standard lengths between 152 and 257 mm and six males with standard lengths between 253 and 209 mm were caught storage crypts with stored spermatozoa and to describe their evolution over the year. After internal fertilization and once sperm reaches the ovary, a crypt forms probably by an epithelial inclusion at the base of the lamellae of one or several spermatozoa groups that are floating freely in the interlamellar space of the ovarian lumen. Stored spermatozoa have a large cytoplasm bag surrounding their heads. This bag could serve as a nutritive reservoir during the long storage period. Many desmosonal and tight junctions between the crypt cells ensure tha male sex cells are protected against the female immune system

Probabilistic models to assist maintenance of multiple instruments

The paper discusses maintenance challenges of organisations with a huge number of devices and proposes the use of probabilistic models to assist monitoring and maintenance planning. The proposal assumes connectivity of instruments to report relevant features for monitoring. Also, the existence of enough historical registers with diagnosed breakdowns is required to make probabilistic models reliable and useful for predictive maintenance strategies based on them. Regular Markov models based on estimated failure and repair rates are proposed to calculate the availability of the instruments and Dynamic Bayesian Networks are proposed to model cause-effect relationships to trigger predictive maintenance services based on the influence between observed features and previously documented diagnostics

Self-deception as a mechanism for the maintenance of drug addiction

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