A New Shock Model for the Effect of Leptin on Body Weight Gain

The present study was designed to examine the dosage effect of the chronic Leptin infusion on body weight gain. Using a new shock model approach, the mean and variance for body weight gain were found. The results are consistent and the shock model concludes that if the dosage of the Leptin increases, the body weight gain decreases. Keywords: New Shock model, Leptin, neuroendocrine, neuropeptides. 2010 Mathematics Subject Classification: 97Mxx, 93A30, 74J4

Molluscicidal effect of biogenic silica and botanical pesticides for the control of Achatina fulica (giant African land snail) and Laevicaulis alte (garden slug)

The molluscicidal effect of silica synthesized from rice husk ash (RHA) on snails (Achatina fulica Bowdich) and slugs (Laevicaulis alte Férussac) was assessed under laboratory conditions. The silica particles derived from RHA were also coated with leaf extracts (botanical pesticides): Azadirachta indica A. Juss, Pongamia pinnata (L.), Nicotiana tabacum (L.), and Calotropis procera (L.). The silica coated with plant extracts and the uncoated silica were applied to the molluscs in dust or slurry form. Inactivation, mortality, and body fluid loss in A. fulica and L. alte were observed over 24 h and recorded. The body fluid losses were 25%–42% for snails and 37%–62% for slugs that had been dusted with silica. During the experiment it was also noted that as the concentration of silica increased (0.15, 0.20, and 0.25 g), the time required for inactivation and mortality was reduced. The dust application was more effective than the slurry. The lower concentration of silica in the slurry (0.05 and 0.10 g) did not have any significant effect on A. fulica or L. alte. For A. fulica the biopesticide-coated silica particles were more effective when coated with neem, followed by tobacco and karanj; for L. alte, the particles were most effective when coated with tobacco, followed by neem and karanj. The plant extract (liquid as well as dry powder) without silica showed no molluscicidal effect on A. fulica and L. alte, except for some temporary inactivation, particularly with tobacco extract. The application of common salt, a practice often used by farmers, was also tested. It was observed that the effects of common salt on A. fulica and L. alte were less significant than those of silica coated with botanical pesticides.

Transgenic neuronal overexpression reveals that stringently regulated p23 expression is critical for coordinated movement in mice

<p>Abstract</p> <p>Background</p> <p>p23 belongs to the highly conserved p24 family of type I transmembrane proteins, which participate in the bidirectional protein transport between the endoplasmic reticulum and Golgi apparatus. Mammalian p23 has been shown to interact with γ-secretase complex, and modulate secretory trafficking as well as intramembranous processing of amyloid precursor protein in cultured cells. Negative modulation of β-amyloid production by p23 in cultured cell lines suggested that elevation of p23 expression in neurons might mitigate cerebral amyloid burden.</p> <p>Results</p> <p>We generated several lines of transgenic mice expressing human p23 in neurons under the control of <it>Thy-1.2 </it>promoter. We found that even a 50% increase in p23 levels in the central nervous system of mice causes post-natal growth retardation, severe neurological problems characterized by tremors, seizure, ataxia, and uncoordinated movements, and premature death. The severity of the phenotype closely correlated with the level of p23 overexpression in multiple transgenic lines. While the number and general morphology of neurons in Hup23 mice appeared to be normal throughout the brain, abnormal non-Golgi p23 localization was observed in a subset of neurons with high transgene expression in brainstem. Moreover, detailed immunofluorescence analysis revealed marked proliferation of astrocytes, activation of microglia, and thinning of myelinated bundles in brainstem of Hup23 mice.</p> <p>Conclusions</p> <p>These results demonstrate that proper level of p23 expression is critical for neuronal function, and perturbing p23 function by overexpression initiates a cascade of cellular reactions in brainstem that leads to severe motor deficits and other neurological problems, which culminate in premature death. The neurological phenotype observed in Hup23 mice highlights significant adverse effects associated with manipulating neuronal expression of p23, a previously described negative modulator of γ-secretase activity and β-amyloid production. Moreover, our report has broader relevance to molecular mechanisms in several neurodegenerative diseases as it highlights the inherent vulnerability of the early secretory pathway mechanisms that ensure proteostasis in neurons.</p

Studies on Batoids Diversity off Rameswaram Island, Tamil Nadu

Gulf of Mannar (GoM) and Palk Bay (PB) are two biodiversity rich ecosystems in the east coast of India as it occupies vast coral reefs, seagrass meadows, sandy and muddy bottoms. Rameswaram Island covers both GoM and PB in its south and north vicinities respectively. Month and season wise species diversity of batoids off the Rameswaram Island analysed. Based on the cyclic phenomena of meteorological events, three seasons are broadly indicated as month wise and they are (1) Pre –Monsoon (PRM) (June to September) (2) Monsoon (M) (October to January) (3) Post-Monsoon (POM) (February-May). The diversity indices calculated using the PRIMER package. In the Rameswaram Island waters, the number of batoid species recorded in various seasons was in the range of 11–40. While the maximum number of species was found in PRM (35), the minimum was found in POM (11). Totally, 40 species of batoids were recorded in the area. These included 21 species belonging to family Dasyatidae, 5 to family Rhinobatidae, 6 to family Mobulidae, 2 each to Rhinopteridae, and Aetobatidae 1 species to families Glaucostegidae, Rhinidae, Gymnuridae and Myliobatidae. Neotrygon indica, was the most dominant species followed by Aetobatus ocellatus., R. javanica, Gymnura poecilura, Brevitrygon imbricata, Himantura uarnak, H. tutul, H. leopard, Maculabatis gerrardi, Taeniurops meyeni, Pateobatis bleekeri and Pastinachus ater were observed in all seasons. The Shannon diversity was more in July (4.60) followed by August (4.45) and June (4.40). The Margalef species richness showed remarkable differences between July (6.12) and April (1.11). The evenness was comparatively more in February (0.97) than July (0.95). Highest Shannon diversity (4.75) and species richness (6.82) was observed in PRM. Species evenness was more in POM (0.94) and least during PRM (0.92). The variation in taxonomic distinctness index was more between PRM and POM (0.962 - 0.912). All three diversity indices in M were intermediate between PRM and POM. PRM and M formed a group with highest similarity percentage of 64.31 to which POM got linked at 32.86

Regulation of Amyloid Precursor Protein Processing by the Beclin 1 Complex

Autophagy is an intracellular degradation pathway that functions in protein and organelle turnover in response to starvation and cellular stress. Autophagy is initiated by the formation of a complex containing Beclin 1 (BECN1) and its binding partner Phosphoinositide-3-kinase, class 3 (PIK3C3). Recently, BECN1 deficiency was shown to enhance the pathology of a mouse model of Alzheimer Disease (AD). However, the mechanism by which BECN1 or autophagy mediate these effects are unknown. Here, we report that the levels of Amyloid precursor protein (APP) and its metabolites can be reduced through autophagy activation, indicating that they are a substrate for autophagy. Furthermore, we find that knockdown of Becn1 in cell culture increases the levels of APP and its metabolites. Accumulation of APP and APP C-terminal fragments (APP-CTF) are accompanied by impaired autophagosomal clearance. Pharmacological inhibition of autophagosomal-lysosomal degradation causes a comparable accumulation of APP and APP-metabolites in autophagosomes. Becn1 reduction in cell culture leads to lower levels of its binding partner Pik3c3 and increased presence of Microtubule-associated protein 1, light chain 3 (LC3). Overexpression of Becn1, on the other hand, reduces cellular APP levels. In line with these observations, we detected less BECN1 and PIK3C3 but more LC3 protein in brains of AD patients. We conclude that BECN1 regulates APP processing and turnover. BECN1 is involved in autophagy initiation and autophagosome clearance. Accordingly, BECN1 deficiency disrupts cellular autophagy and autophagosomal-lysosomal degradation and alters APP metabolism. Together, our findings suggest that autophagy and the BECN1-PIK3C3 complex regulate APP processing and play an important role in AD pathology

Amyloid Precursor Protein Is Trafficked and Secreted via Synaptic Vesicles

A large body of evidence has implicated amyloid precursor protein (APP) and its proteolytic derivatives as key players in the physiological context of neuronal synaptogenesis and synapse maintenance, as well as in the pathology of Alzheimer's Disease (AD). Although APP processing and release are known to occur in response to neuronal stimulation, the exact mechanism by which APP reaches the neuronal surface is unclear. We now demonstrate that a small but relevant number of synaptic vesicles contain APP, which can be released during neuronal activity, and most likely represent the major exocytic pathway of APP. This novel finding leads us to propose a revised model of presynaptic APP trafficking that reconciles existing knowledge on APP with our present understanding of vesicular release and recycling