Engineering aspects to be taken care in cage culture of seabass (Cage designs and materials, Mooring materials, Net load calculations etc.)

Aquaculture systems are very diverse in their design and function. The three most basic categories of culture systems are: i) Open systems, ii) Semi closed and iii) Closed systems. Modern cage culture began in 1950’s with the advent of synthetic materials for cage construction. The major advantage of cage culture is use of existing water bodies, technical simplicity, simplified harvest and low capital cost compared with land based farm. But it has got certain disadvantages like feed must be nutritionally balanced, pollution, out break of disease, vandalism etc

An approach to obtain specific polyclonal antisera to Xanthomonas campestris pv. cyamopsidis and its potential application in indexing of infected seeds of guar

Clusterbean seed health testing is warranted since the pathogen (Xanthomonas campestris pv. cyamopsidis (Xccy)) is seed-borne and seed-transmitted. A polyclonal antibody was developed in rabbit via subcutaneous and intramuscular injections and characterized for sensitivity, specificity and its applicability to ELISA which: (i) was sensitive in detecting as few as 102 cells ml−1 at a titre of 1:4000; (ii) was specific, since it reacted only with Xccy and not with other xanthomonads; (iii) reacted both with Xccy cells and culture filtrate, indicating that the antigenic determinant is a secretory component; (iv) was applicable and reliable in seed health testing since it reacted only with infected seeds and plant materials and not with healthy seeds and (v) a purified fraction of antibody was virulent-specific since heat-denatured and avirulent isolates were not detected. The ELISA thus developed is highly reproducible and therefore suitable for the evaluation of the potential disease status of seeds and plant health, which is appropriate for routine seed health testing

Assessment of non-degradable litter and its impact on the benthic community of selected mangrove ecosystems of Kerala, India

Inadequate management of non-degradable litter in coastal areas can lead to its accumulation in mangrove forest, affecting its ecosystem services. Abundance and distribution of marine litter and its impact on benthic organisms in mangrove ecosystems are far less investigated in India. Thirteen mangrove ecosystems distributed in Ernakulum District, Kerala were selected for the study and evaluated for plastic pollution

Impact of plastic litter - a quantitative and qualitative investigation in selected mangrove distributions, Kerala, India

Mangrove forests possess an incredible biodiversity and the ecosystem services they provide include food, shelter and nursery to number of species. The services they contribute to human are also valuable as their capacity to protect us from natural disasters namely shore line stabilization, carbon sequestration and many more. But, today the developmental pressures caused by growing human population seriously impacts this fragile ecosystem resulting in its degeneration to a great extent. Apart from the pollution caused by thermal, agrochemical, heavy metal and oil spill, one of the burning issues which results in its imbalance today is the accumulation of nondegradable plastic litter, which gets entrapped in the root system caused due to mismanaged waste disposal. The partially emerged root system of mangroves forms an effective filter that attenuates wave energy and turbulence and may possibly trap objects transported by currents, like floating plastic objects. (Horstman et al., 2014; Norris et al., 2017). This results in preventing gas exchange and releases harmful chemicals associated with plastic materials

Hesperidin Ameliorates Immobilization-Stress-Induced Behavioral and Biochemical Alterations and Mitochondrial Dysfunction in Mice by Modulating Nitrergic Pathway

The present study was aimed to evaluate the protective effect of hesperidin against immobilization-stress-induced alterations in biochemical, behavioral, and mitochondrial functions in mice. In many instances neuroscientists have reported that acute immobilization stress for 6 h resulted in anxiety and impaired locomotor activity due to excess oxidative-nitrergic stress, depletion of antioxidant defense mechanisms, and mitochondrial dysfunction in animals. In the present study, 6 h of acute immobilization stress had significantly altered the behavioral (anxiety and memory) and biochemical parameters coupled with mitochondrial dysfunction in Swiss albino mice. Fourteen days of pretreatment with Hesperidin (50 and 100 mg/kg, p.o.) significantly and dose-dependently inhibited the behavioral and biochemical alterations and mitochondrial dysfunction caused by acute immobilization stress. Furthermore, pre-treatment of l-arginine (50 mg/kg, i.p.), a nitric oxide precursor, reversed the protective effect of Hesperidin (50 and 100 mg/kg) (P < 0.05). In contrast, pretreatment of l-NAME (5 mg/kg, i.p.), a nitric oxide synthase inhibitor, potentiated the protective effect of Hesperidin (P < 0.05). These results suggest the possible involvement of nitrergic pathway in the protective effect Hesperidin against immobilization-stress-induced behavioral, biochemical, and mitochondrial dysfunction in mice

Assessment of marine debris in the stake net fisheries of Vembanad Lake, Kerala, India

The stake net fishery of Panambukad in the main channel area of Vemband Lake, Kerala was studied during the first fortnight of August 2014. The observations indicated that the average catch including the marine debris ranged from 1.04 to 2.04 kg net-1 day-1 with an average of 1.34 kg net-1 day-1. The percentage of marine debris in the stake nets ranged from 42.68 to 73.4%. Plastic items formed 97% by weight and 99% by number of the total marine litter. The observed litter stuff was categorized as per UNEP system of classification of marine litter where, they are first identified based on their material composition (litter codeeg. PL) and then by their form (RL classes). Items found in the collection included plastic covers (PL07, RL15), metal cap (ME02, RL01), plastic bottle (PL02, RL02), fishing net (PL20, RL05), plastic cup and food containers (PL06, RL09), thermocol (FP 04, RL13), rubber sheet (RB05, RL28), plastic sacks (PL24, RL23), diaper (OT02, RL18) etc. Among them, plastic covers were most dominant and their average number and weight net-1 day-1 was 28 nos and 985 g respectively. The study also showed positive signs of decline in plastic bottles as a major litter item due to its targeted collection by recycling industry within a span of three years. In a survey conducted among the stake net fishers, there was consensus on the view that plastic litter in Vembanad Lake has increased during the last 10 years and this has affected the resources and the fishery. The stakeholders also expressed their willingness to pay for restoration of the fishery resources of the lake. The study recommends the need to establish proper solid waste management systems in coastal villages, to reduce the use of plastics, and provide facilities for disposal of litter which gets collected in stake nets and to increase the awareness among the public about the impacts of marine debris on ecosystem and resources

Observations on selected characteristics of water and sediment at the open sea cage culture site of Asian seabass Lates calcarifer (Bloch) off Cochin, south-west coast of India

Study was undertaken to assess the impact of open sea cage culture of Asian seabass Lates calcarifer on selected parameters of water as well as sediment at Munambam off Cochin, Kerala coast from November 2008 to March 2009. Periodic observations were made on temperature, pH, dissolved oxygen, salinity, nutrients (NO3, PO4, SiO3), nitrite, ammonia, BOD, total suspended solids, chlorophyll a, gross and net primary productivity as well as bacterial load of the surface and near bottom water from the cage site (N 10º 08' 162''; E 76º 08' 901'') and also from a reference site (N 10º 07' 189''; E 76º 09' 210'') during pre- as well as post-stocking periods. Sediment samples were collected simultaneously from both the sites and analysed for texture, pH, organic carbon and bacterial load. A significant reduction (p<0.05) in silicate and chlorophyll a was perceived in surface water at the cage site, during the culture period as compared to pre-stocking period. No significant variations were noticed in any of the other parameters studied. The sand, silt, clay and organic carbon content in sediment at cage site differed significantly (p<0.05) from that of the reference site. There was no significant difference in the mean values of total heterotrophic bacterial count as well as presumptive Vibrio count of the water and sediment, either between the cage site and reference site or between the pre- and post-stocking samplings. No adverse effect as influenced by cage culture of fish was observed on any of the environmental parameters studied during the period of investigation

Diversity and distribution of shallow water sponges (Porifera) in the coastal waters from Enayam to Kollam, south-west coast of India

Underwater surveys were conducted in the shallow coastal waters extending from Enayam to Kollam, southern India, covering six study locations viz., Enayam, Adimalathura,Vizhinjam, Varkala, Odayam and Paravoor to record the diversity of sponges. A total of 24 species of sponges were identified during the study which belonged to 20 genera, 14 families and 6 orders. Maximum species diversity was recorded at Enayam (11 species), followed by an equal number of species at Vizhinjam and Adimalathura (10 species). Five species of sponges were recorded at Odayam while three species were recorded at Varkala and only one at Paravur. Shannon diversity was high at Enayam, Vizhinjam and Adimalathura and the dominance plot also showed rich diversity of sponges in these three stations.The cluster results using Bray Curtis similarity Index indicated two clusters: stations Enayam, Vizhinjam and Adimalathura showed one cluster indicating similarity of species in these stations, while the stations Varkala, Odayam and Paravoor showed another cluster. The present study has indicated that the stations Enayam, Vizhinjam and Adimalathura are rich in diversity and abundance of sponges, compared to Varkala, Odayam and Paravoor

The Structure of the Phage T4 DNA Packaging Motor Suggests a Mechanism Dependent on Electrostatic Forces

SummaryViral genomes are packaged into “procapsids” by powerful molecular motors. We report the crystal structure of the DNA packaging motor protein, gene product 17 (gp17), in bacteriophage T4. The structure consists of an N-terminal ATPase domain, which provides energy for compacting DNA, and a C-terminal nuclease domain, which terminates packaging. We show that another function of the C-terminal domain is to translocate the genome into the procapsid. The two domains are in close contact in the crystal structure, representing a “tensed state.” A cryo-electron microscopy reconstruction of the T4 procapsid complexed with gp17 shows that the packaging motor is a pentamer and that the domains within each monomer are spatially separated, representing a “relaxed state.” These structures suggest a mechanism, supported by mutational and other data, in which electrostatic forces drive the DNA packaging by alternating between tensed and relaxed states. Similar mechanisms may occur in other molecular motors

Do fishes consume plastics? If so, are they always dangerous?

Plastics have tremendous advantages and utility in the present world but its indiscriminate discard creates a pathway to water bodies and eventually forming a threat to aquatic organisms. The large plastics (macro plastics) can degrade and become smaller meso or micro plastics which can be ingested by fishes and invertebrates. Low density plastics (eg. Poly propylene or polyethylene) are dominant in the top layers for a certain period of their entry, may suffer biofouling causing it to sink gradually. High density plastics (PVC, Polyester and polyamides) usually sink to the bottom. Macro, Meso and Micro polymers selected for the study were polypropylene, polyethylene and polyvinyl chlorid