Studies on arsenical creosote as a wood preservative for marine structures. Part 2. Observation on leaching, corrosion and resistance to borer attack

A detailed study on arsenical creosote with reference to leaching, corrosion and anti-borer properties was carried out. Results showed that aging had very little effect on the preservative which suggested better fixation of the preservative into the wood. Corrosion of mild steel, galvanised iron, aluminium-magnesium alloy (M57S) and copper panels in the preservative was found to be negligible. Normal creosote and low temperature creosote of Regional Research Laboratory, Hyderabad, both fortified with arsenic trioxide resisted borer damage on wooden panels for a period of over five months in the port of Cochin. The performance of low temperature creosote fortified with arsenic was found to be equally satisfactory when compared to normal creosote fortified in the same manner. A loading of 208.6 Kgs/ml³ for Haldu (Adina cordifolia) and 138 Kgs/m³ for Mango (Mangifera indica) in the case of normal creosote and 177 Kgs/m³ for Mango the case of RRL creosote were found to be sufficient for treating the wood.

A case history on the phenomenal corrosion of marine propellers in fishing boats

Although high tensile brassess of copper-zinc alloys (Manganese bronze) find extensive use in all marine applications, under aggressive sea-water, marine propellers cast out of such an alloy frequently suffer heavy corrosion damages due to dezincification. An interesting case history where a number of propellers have undergone dezincification in the Cochin backwaters is narrated in this paper.

On the importance of ship-bottom fouling by marine organisms: a techno-economic survey

A high attention has been paid for constant research on the preservation of materials in the marine environment. This includes all phases of design, development, applied engineering and economics which may influence the construction and operation of ships and underwater installations.

Occurrence of Vibrio parahaemolyticus in marine prawns and environments

Qualitative studies on the microflora of slime and guts of prawns and of sea water off Nagapattinam showed the presence of Vibrio in the slime and sea water. They were further tested for Vibrio parahaemolyticus types and related bio-types. Evidence of its occurrence is given. This points to the need for further studies on the distribution of this organism in terms of public health significance.

Molecular phylogenetics and the origins of placental mammals

The precise hierarchy of ancient divergence events that led to the present assemblage of modern placental mammals has been an area of controversy among morphologists, palaeontologists and molecular evolutionists. Here we address the potential weaknesses o

Development of electro-trawl system in marine environment

High voltage pulsed current produced on board a trawler is fed to electrodes distributed along the foot rope of a trawl net through two core TRS cable which builds up a homogeneous electrical field around the net mouth. By comparative fishing tests with the electrified and non-electrified 32 m long wing trawl net, the increase in total catch of shrimps and fishes was found to be 19.8 and 36%, respectively.

Lipid distribution in body and skin of four species of marine fish

The paper presents results of a study on the analytical characteristics of lipids from the skin and muscle of four important species of Gujarat coast fishes. Changes in characteristics like saponification value, iodine value and unsaponifiable matter of these lipids during different months of the year are also reported.

Nucleotide degradation and production of hypoxanthine in some Indian marine and freshwater fishes

Changes in nucleotides and production of hypoxanthine in rohu (Labeo rohita), mrigal (Cihhrina mrigala) and common carp (Cyprinus carpio) during storage at 2-4°C were examined. Differences were observed between common carp and others. Production of hypoxanthine in pomfret (Stromateus argenteus), cat fish (Arius macronotacanthus), shark (Scoliodon spp.), seer fish (Scomberomorus guttatus), ray fish (Dasyatis imbricata) and prawns (Parapenaeopsis stylifera) was examined during storage at 2-4°C and -28°C. At 2-4°C hypoxanthine increased regularly but at -28°C there was no increase during storage over 28 weeks.

Chemical control of psychrophilic bacterial spoilage of fish 1. Isolation and identification of psychrophilic bacteria from marine fish

Making use of the streak plate technique and low temperature incubation, 28 cultures belonging to six genera namely, Achromobacter, Flavobacterium, Pseudomonas, Micrococcus, Vibrio and Alcaligenes were isolated from different varieties of marine fish. The growth studies indicated that all of them were able to grow between -5 and +5°C within a week's time and none of them showed growth at 37°C. The optimum temperature of growth for all these cultures was in the range 25-28°C. Among these only one, i.e., a Vibrio sp., was found to be an obligate psychrophile.

Episodic evolution of prolactin receptor gene in mammals: coevolution with its ligand

Divergence of proteins in signaling pathways requires ligand and receptor coevolution to maintain or improve binding affinity and/or specificity. In this paper we show a clear case of coevolution between the prolactin (PRL) gene and its receptor (prolactin receptor, PRLR) in mammals. First we observed episodic evolution of the extracellular and intracellular domains of the PRLR, which is closely consistent with that seen in PRL. Correlated evolution was demonstrated both between PRL and its receptor and between the two domains of the PRLR using Pearson's correlation coefficient. On comparing the ratio of the nonsynonymous substitution rate to synonymous substitution rate (omega=d(N)/d(S)) for each branch of the star phylogeny of mammalian PRLRs, separately for the extracellular domain (ECD) and the transmembrane domain/intracellular domain (TMD/ICD), we observed a lower omega ratio for ECD than TMD/ICD along those branches leading to pig, dog and rabbit but a higher ratio for ECD than TMD/ICD on the branches leading to primates, rodents and ruminants, on which bursts of rapid evolution were observed. These observations can be best explained by coevolution between PRL and its receptor and between the two domains of the PRLR.

Evolutionary implications of multiple SINE insertions in an intronic region from diverse mammals

An analysis of the nuclear beta-fibrinogen intron 7 locus from 30 taxa representing 12 placental orders of mammals reveals the enriched occurrences of short interspersed clement (SINE) insertion events. Mammalian-wide interspersed repeats (MIRs) are present at orthologous sites of all examined species except those in the order Rodentia. The higher substitution rate in mouse and a rare MIR deletion from rat account for the absence of MIR in the rodents. A minimum of five lineage-specific SINE sequences are also found to have independently inserted into this intron in Carnivora, Artiodactyla and Lagomorpha. In the case of Carnivora, the unique amplification pattern of order-specific CAN SINE provides important evidence for the "pan-carnivore" hypothesis of this repeat element and reveals that the CAN SINE family may still be active today. Particularly interesting is the finding that all identified lineage-specific SINE elements show a strong tendency to insert within or in very close proximity to the preexisting MIRs for their efficient integrations, suggesting that the MIR clement is a hot spot for successive insertions of other SINEs. The unexpected MIR excision as a result of a random deletion in the rat intron locus and the non-random site targeting detected by this study indicate that SINEs actually have a greater insertional flexibility and regional specificity than had previously been recognized. Implications for SINE sequence evolution upon and following integration, as well as the fascinating interactions between retroposons and the host genomes are discussed.

Mercury toxicity in two intertidal tropical marine molluscs

Lethal and sub-lethal effects of mercury have been studied in Perna viridis and Modiolus carvalhoi. For P. viridis LC30 is 1.0 p.p.m. at 48 h and 0.23 p.p.m. at 96 h. Recorded LC50 values for M. carvalhoi are 0.5 p.p.m. and 0.19 p.p.m. at 48 h and 96 h respectively. The results document that these two species, although inhabiting the same area in the tidal belt, exhibit clear differences in mercury resistance. It is further shown that the duration of exposure affects mortality rates. In sub-lethal concentration, between 0.01 and 0.10 p.p.m. decrease in pedal-gland activity is conspicuous in P. viridis. At concentrations much below LC50 values (at 96 h), although some animals are alive, pedal-gland activity is totally suspended, supporting the assumption that shell closure ability plays a minor role in byssus thread production. In M. carvalhoi total cessation of pedal gland activity occurred at 0.09 p.p.m. of mercury.

Copper-nickel alloys for marine aquacultural engineering

Engineering developments, problems of marine corrosion, fouling and practical innovative applications of copper-nickel alloys in comparison with other materials for marine aquacultural engineering are presented. Coefficient of drag and hydrodynamic force acting on nylon and polyethylene net enclosures have shown a four-fold increase of force in four months at the Cochin harbour due to fouling. Corrosion behaviour of copper-nickel and other copper base alloys are also presented. Effects of copper additions to culture water are reviewed.

Salt tolerance of bacteria isolated from tropical marine fish and prawn

Salt tolerance of selected cultures of Pseudomonas, Moraxella, Vibrio, Micrococcus, Acinetobacter and Flavobacteria/ Cytophaga was determined. More than 80% of the cultures belonging to each of the above genera, were capable of growth in presence of 1.5 to 3.5% salt (NaCl) and at least 25 to 30% of the cultures in each group required 1.5 to 3.5% salt for growth. 40% each of Pseudomonas and Vibrio strains and 30% each of Moraxella, Micrococcus and Flavobacteria/Cytophaga strains tolerated 10% salt. Majority of the cultures belonging to the genera Pseudomonas, Vibrio, Moraxella, Micrococcus, Acinetobacter and Flavobacteria/Cytophaga were slightly halophilic (2 to 5% salt tolerant), about 25% especially of Micrococcus spp. moderately halophilic (5 to 20% salt tolerant) and none from Pseudomonas, Vibrio, Moraxella, Acinetobacter and Flavobacteria/Cytophaga spp. extremely halophilic (20 to 32% salt tolerant).

Evolution of cd59 gene in mammals

The CD59-coding sequences were obtained from 5 mammals by PCR and BLAST, and combined with the available sequences in GenBank, the nucleotide substitution rates of mammalian cd59 were calculated. Results of synonymous and nonsynonymous substitution rates