Spatial Variation of Zooplankton in Sundarban Mangrove Wetland, Northeastern Part of the Bay of Bengal

-- Santosh Kumar Sarkar,
Bhaskar Deb Bhattacharya and Soumik Saha

The paper deals with the spatial diversity of surface zooplankton in relevance with water quality parameters (water temperature, pH, salinity, turbidity, transparency, dissolved oxygen, biological oxygen demand, chemical oxygen demand, nutrients and chlorophyll pigments—a, b and c) in six stations of the lower stretch of the Hugli estuary, Sundarban, northeastern part of the Bay of Bengal, India. The work has been undertaken for a better understanding of its ecological characteristics in terms of secondary production. Copepods were the most dominant group consisting of 27 species followed by chaetognaths, lucifers, hydromedusae and ctenophores as holoplankters. They constituted the bulk of the biomass sharing 43.13 to 96.55% of the total zooplankton. Correlation matrix showed interesting relationship among the major copepods and also between the water quality parameters, total zooplankton and copepods. Copepods of the low saline upstream assemblage showed a decrease in abundance. The scarcity of the mature chaetognath Sagitta bedoti might be attributed to their presence in the deeper layers. Spatial heterogeneity of zooplankton distribution, especially the copepods, was pronounced revealing different biological characteristics of the wetland.

© 2007 IUP . All Rights Reserved.

Biological Control of Leaf Spot Disease of Vanilla by Pseudomonas fluorescens

-- Kannan V, Sureendar R and Manchu Mohan

The phylloplane and rhizosphere soil samples were collected from different plants and the bacterial isolates obtained were screened for their efficiency to check Fusarium oxysporum (causal agent of root rot of Vanilla plant). An isolate from rice rhizosphere was found to be efficient in controlling the pathogen, and its growth promoting activity was checked through Indole-3-Acetic Acid (IAA) production. The disease suppression activity was estimated by dual plate assay in vitro and pot culture experiments. The pathogenicity related enzymes such as Phenylalanine Ammonia Lyase (PAL), Transaldolase (TAL), Catalase and Peroxidase, and compounds such as phenols in test Vanilla plants were recorded to be enhanced and correlated with disease suppression.

© 2007 IUP . All Rights Reserved.

The Effect of Defoliation of Lower Leaves and Nitrogen Application Rate on N Assimilation, Photosynthesis, Growth and Yield of Mustard (Brassica juncea L.)

-- P M Lone, N A Anjum, R Nazar and N A Khan

Mustard (Brassica juncea L.) is characterized by high nitrogen (N) requirement for improved productivity and a large number of broad leaves in lower layers. The N applied to the soil is not fully utilized by the crop due to various constraints and the leaves in the lower layers remain below light compensation photosynthetic point. Earlier researches have shown that an early removal of 50% lower leaves enhances photosynthesis and growth of mustard. The present paper evidences that the activities of N assimilation enzymes, nitrate reductase, nitrite reductase and glutamine synthetase increase in defoliation plants, increasing photosynthesis, growth and yield. Application of 150 kg N ha^-1 at sowing time and defoliation at pre-flowering i.e., 40 d after sowing increased N assimilation, photosynthesis and growth maximally than no defoliation and 150 kg N ha^-1. The other N rates (0, 60 or 100) and defoliation treatment proved less effective. The redistribution of photoassimilates towards developing sink in plants subjected to defoliation and given 150 kg N ha^-1 enhanced seed yield substantially. The results suggest that plants assimilated N more efficiently after defoliation, increasing photosynthesis, growth and yield. This management practice could be adopted in mustard cultivation for increasing seed yield and decreasing N wastage.

© 2007 IUP . All Rights Reserved.

Pathophysiology of Obesity Linked Diabetes

-- Sushumna Sood

Obesity is commonly associated with insulin resistance and hyperinsulinemia and is a major risk factor for the development of type-2 diabetes. Obesity and diabetes tend to occur together because carbohydrate metabolism and body weight gain regulation rely on common hormonal (insulin and leptin) and CNS signaling system. It is clear that obesity is associated with a state of chronic low-level inflammation (in white adipose tissue) and inflammation contributes to insulin resistance. Although adipose tissue is known to express and secrete a variety of metabolites, hormones and cytokines that have been implicated in the development of insulin resistance, the molecular basis for the link between obesity and diabetes is still not very clear. While free fatty acids released from adipose tissue have long been implicated in the development of obesity linked diabetes, it is now apparent that there is an overlap among the hormones, neuropeptides, signaling molecules and inflammation in these two disorders. This sharing might play an important role in the pathophysiology of these two syndromes. The article mainly focuses on the role of insulin, leptin, brain, and inflammation and stress as major elements which participate in the pathophysiology of obesity linked diabetes.

© 2007 IUP . All Rights Reserved.

Research Note

Lecithochirium anisotestes n.sp. (Digenea: Hemiuridae) from the Marine Lizard Fish Saurida tumbil from the Visakhapatnam Coast

-- P Surekha and C Vijayalakshmi

Hemiurids are the group of digeneans which usually occur in the mucosa of stomach of marine teleosts. The genus Lecithochirium was erected by Luhe (1901) which is a large genotype and is the most frequently encountered hemiurid in fishes of east coast. They are usually parasitic in the gut of the marine teleosts. The taxonomic history of hemiurid digeneans has been reviewed by Gibson and Bray (1979). More than 100 species have been described in this genus. Bray (1990) synonymized a number of these species. These worms are generally more morphologically complex than the hemiurids treated earlier. The ecological, physiological and environmental factors of these hosts and adaptations of parasites might have led to morphological variations of flukes.

© 2007 IUP . All Rights Reserved.

Screening of Some Coastal Medicinal Plants for Antibacterial Studies

-- Ramanathan T

Natural products of higher plants may offer a new source of antibacterial agents (Brunter and Grein, 1994). Microbiologists and pharmacological scientists are now in search of new antibiotics that could be used to combat illness caused by resistant microorganisms. However, the potential of the plants as sources of new drugs is still largely unexplored.

© 2007 IUP . All Rights Reserved.

Analyses of Total Count of Hemocytes of Estuarine Crab, Scylla serrata Under Acute Arsenic Exposure

-- Sanjib Saha, Mitali Ray and Sajal Ray

Estuarine mud crab, Scylla serrata (Crustacea: Decapoda) is an economically important edible species. The crustacean is widely distributed in the mud flat of the intertidal zone of Sunderban delta of West Bengal (Ali et al., 2004). Different toxicants, heavy metals and pesticides have a major role in the contamination of the aquatic ecosystem (Eisler, 1988; Selvakumar et al., 1996; Shibu Vardhanan and Radhakrishnan, 2002). All the pollutants released on land eventually find their way to the rivers and oceans as the final repository. Since the estuaries are the links to the freshwater and marine systems, they contain a variety of anthropogenic chemicals referred to as xenobiotics, viz., heavy metals, pesticides, fertilizers, etc., (Vijayavel and Balasubramanian, 2005).

© 2007 IUP . All Rights Reserved.