Narrow-linewidth broadly tunable Yb-doped Q-switched fiber laser using multimode interference filter.

A narrow-linewidth broadly tunable Yb-doped Q-switched fiber laser using an acousto-optic modulator and multimode interference filter (MMIF) in the linear bulk cavity resonator and an all-fiber ring cavity resonator has been demonstrated. Insertion of an MMIF in the linear cavity resonator using bulk components decreased the spectral bandwidth of the Q-switched signal by two orders of magnitude from 11 to less than 0.1 nm. Spectral tunability of more than 16 nm in the range from 1057 to 1073 nm has also been achieved by the combination of MMIF and a standard polarization controller (SPC). A decrease in the pulse duration with a decrease in the spectral bandwidth of the output signal has also been recorded. The pulse duration of the Q-switched signal was reduced from ∼305 to ∼240 ns by the introduction of the MMIF in the resonator at the same value of the input pump power. In the case of the all-fiber Q-switched ring cavity resonator, the spectral bandwidth of the Q-switched signal was reduced by two orders of magnitude from ∼17 to less than 0.1 nm due to the introduction of the MMIF in the resonator. The spectral tunability of more than 12 nm in the range from 1038 to 1050 nm was achieved by an MMIF and an SPC.

Modulation of digestive enzyme activities during ontogeny of Labeo rohita larvae fed ascorbic acid enriched zooplankton.

The effect of supplementation of ascorbic acid through enriched zooplankton [10%, 20% and 30% ascorbyl palmitate (AP) inclusion in diet of zooplankton] on different digestive enzyme activities during ontogeny of Labeo rohita larvae was studied from 4 day to 15 day post hatch. Ascorbic acid (AA) content in different groups of unenriched (8.6+/-0.71) and enriched zooplankton were, 750+/-29.3, 1409.1+/-45.5, 2009.21+/-199.2 mug/g respectively on dry matter basis with differences (P<0.05) between the treatments. A difference (P<0.05) was found in tissue AA level in different dietary groups. Low amylase, protease, lipase and alkaline phosphatase activities were present in rohu larvae from the mouth opening stage which showed increasing trend with the age of larvae and increasing dietary AA content. A clear dose-dependent modulation of digestive enzyme activities in response to 10%, 20% and 30% AP enriched zooplankton feeding was evidenced from positive correlations between dietary AA content with magnitude of elevation of enzyme activity in different groups. There were 57, 55, 29.2 and 2 fold increases in amylase activity; 7.35, 7.02, 4.43 and 2.73 fold increases in protease activity; 45.636, 41.50, 19.83 and 13.69 fold increases in lipase activity and 6, 5, 3, and 2 fold increases in alkaline phosphatase activity observed in the 15th day post hatch larvae fed 20%, 30%, 10%AP enriched and normal zooplankton respectively, than 4-day post hatch larvae of the respective groups. Enzyme activities were also positively correlated with specific growth rates of wet weight of rohu larvae at the 15th day post hatch. Increased AA might have played an important role in advancing morphological transformation of the digestive tract, protecting gastric mucosa and accelerating growth by the process of tissue formation, which necessitated the requirement of more nutrient thereby, increasing digestive enzyme activity. The regulatory role of AA in the modulation of different digestive enzymes activity and its physiological consequences of nutrient digestibility and utilization during ontogenesis could be extrapolated for better nutrient management of the larvae.

Evaluation of water productivity and fish yield in sewage-fed vis-à-vis fertilized based carp culture.

Reuse of wastewater in aquaculture provides a scope to enhance water productivity of the system. Quantification of nutrient inputs incorporated through treated domestic sewage with varying dosages viz. 79.3 x 10(5)lha(-1) and 67.7 x 10(5)lha(-1) and water productivity in a controlled carp culture system were assessed in comparison to those involved in a fertilized based one, with a view to correlate among physical, chemical and biological processes involved in fish yield under the systems. The net water productivities were measured on the basis of net return values (in Indian rupees; INR) from the carp production systems at a stocking density @ 5000 per ha with four species combination. Selected relevant water parameters such as dissolved oxygen, total alkalinity, biochemical oxygen demand (BOD5) in sewage effluent and fertilizer based systems were monitored along with certain biological parameters viz. gross primary productivity, fish production and water productivity. The nutrient inputs in terms of total ammonia-nitrogen (TAN) in effluents, total nitrogen (TN) in fertilizers and phosphorus (P2O5) in both effluents and fertilizers were found significantly correlated with biological production. The results of the experiment revealed that the sewage incorporation at 79.3 x 10(5)lha(-1) yielded similar gross fish production as recorded from fertilizer based system, whereas net water productivity using sewage as nutrient source was found 64% higher than that of a fertilizer based system.

Magnetic field induced synthesis and self-assembly of super paramagnetic particles in a protein matrix.

Aqueous solution of a globular protein named bovine serum albumin was homogeneously mixed with ferrous and ferric ions and allowed to gel at ambient conditions. Gels were then oxidized using sodium hydroxide, in the presence of magnetic field of magnitude 0.13 T. The effect of magnetic field on the above biomimetic synthesis was a reduction in particle size and a directional assembly of synthesized super paramagnetic particles into a regular pattern in the protein film. The microstructural revelation was complimentary to Mossbauer results and magnetic measurement studies, i.e., an interesting variation in the magnetic behaviour of self-assembled super paramagnetic particles as a function of dc magnetic field induced ordering.

Utilization of fermented silkworm pupae silage in feed for carps.

Fermented silkworm pupae (SWP) silage or untreated fresh SWP pastes were incorporated in carp feed formulations replacing fishmeal. The feed formulations were isonitrogenous (30.2-30.9% protein) and isocaloric (ME = 2905-2935 kcal/kg). Feeding under a polyculture system consisting of 30% each of catla (Catla catla), mrigal (Cirrhinus mrigala) and rohu (Labeo rohita) with 10% silver carps (Hypophthalmychthys molitrix) was carried out in ponds to evaluate the nutritive quality of SWP silage. Survival rate, feed conversion ratio and specific growth rate, respectively, were 84.2%, 2.10 and 2.39 for fermented SWP silage, 65.8%, 2.98 and 2.26 for untreated SWP and 67.5%, 3.16 and 2.20 for fishmeal indicating clearly that the fermented SWP silage was nutritionally superior to untreated SWP or fishmeal. The dietary influence on the proximate composition of whole fish was marginal.

Effect of dietary supplementation of fatty acids and vitamins on the breeding performance of the carp Catla catla.

Five isonitrogenous diets (approximately 33% crude protein) were fed to the brood female carp, Catla catla (weighing 3.0 to 5.5 kg), for a period of 93 days in order to observe their breeding performance in earthen ponds. Diet-I (control) contained only basic ingredients like rice bran, ground-nut oil cake, roasted soybean meal, fish meal and mineral mixture; diet-II contained added vitamins; diet-III contained added vitamins and vegetable oil (rich in n-6 polyunsaturated fatty acids, PUFA); diet-IV contained added vitamins and fish oil (rich in n-3 PUFA); and diet-V contained added vitamins and a mixture of vegetable and fish oils. The results showed that nutritional quality of the diet considerably influenced breeding performance in the species. The total number of matured females was the highest in the diet-V group and maturity was advanced by 35 days in this group compared to the control. In diet-III and diet-V groups, all the maturated females bred fully and the relative fecundity was increased significantly in diet III, IV and V. The maximum (73.4%) fertilisation rate was observed in the diet-V group, followed by 61.3%, 56.8%, 49% and 22.7% in diet-I, diet-IV, diet-III and diet-II groups respectively. Most of the eggs in the diet-II treatment group remained immature. The various data thus obtained suggest that dietary supplementation of both n-3 and n-6 PUFA, is essential to improve gonadal maturation, breeding performance and spawn recovery in the Catla female broodstock.

Carbohydrate-binding profile of a pregnancy-associated rat uterine glycoprotein.

Sugar-binding proteins obtained from the peri-implantation uterine tissue have been thought in recent years to have significant roles in embryo implantation, where carbohydrate moieties of the protein are actively involved. Based on this rationale a mannose-containing glycoprotein/lectin (named uterine agglutinin or UA) was purified by Concanavalin A (Con A) affinity chromatography in a previous study. A modification of the original purification procedure to include a 33% ammonium sulfate fractionation improves the yield of the protein significantly. An alternative purification procedure by Mannan affinity matrix, indicates that apart from containing mannose, UA possesses mannose-binding properties as well. In this paper, we report some of the biochemical and more specifically, the carbohydrate-binding characteristics of UA. The protein is seen to contain mannose-6-phosphate (M-6-P)-binding sites, which is of importance since M-6-P receptors have a large number of biologically significant roles, including that of binding to growth factors. SDS-PAGE, gel filtration chromatography and alkaline PAGE indicate the homogenous nature of the protein with subunit molecular weights of 36 kDa and 19 kDa, and a native size of 64 kDa. Amino acid analysis shows glycine, glutamic acid and aspartic acid to be the major constituents. UA is a glycoprotein and shows presence of N-acetyl glucosamine and galactose, apart from mannose. De nove synthesis studies in the presence of tunicamycin show that the carbohydrate moiety of the glycoprotein is attached by N-linkage to the protein. Binding characteristics of the protein is studied quantitatively in which (125I)-labelled lectin is bound to Mannan-Sepharose affinity matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogeny and implication of pregnancy-associated agglutinin of the rat uterus.

The mannose/fructose-binding agglutinin from Day 1-7 post coitum (p.c.) rat uteri was purified on Concanavalin A. The specific haemagglutination activity peaked on Days 4 and 5 p.c. and a 1.4-fold increase in the yield was accompanied by a 10-12-fold increase in specific agglutination titre. The mannose-binding affinity of the protein also increased, but the highest fructose-binding affinity was found on Day 1 p.c., which may indicate a role of the protein in fructose concentration for utilization by the spermatozoa. Rats that were pseudopregnant, superovulated and pseudopregnant, and had one uterine horn ligated showed that, although a basal level of the protein was induced by the hormonal milieu, actual stimulation of the protein synthesis occurred in the presence of the fertilized ova.

Certain biochemical responses in the air-breathing catfish Clarias batrachus exposed to sublethal carbofuran.

Biochemical changes in the air-breathing catfish, Clarias batrachus (Linn.) exposed to a sublethal level of carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) at 0.5 ppm concentration in ambient water for a period of 30 days were assessed. A small reduction in growth rate was observed in the fish treated with 0.5 ppm carbofuran for 60 days although no mortality or any apparent symptom of toxicity could be noted. Studies were carried out on the activities of certain enzymes of intermediary metabolism viz., glucose 6-phosphatase, alkaline phosphatase, acid phosphatase, Na+, K+-ATPase, GOT and GPT in certain vital tissues of the fish exposed to carbofuran (0.5 ppm) for 30 days. Exposure to carbofuran resulted in sharp inhibition of acetylcholinesterase activity in brain of the fish which recovered rather rapidly after terminating pesticide treatment and maintaining the fish in clean freshwater. Ratio of the levels of calcium/phosphorus in serum showed significant diminution in experimental groups of fish compared to controls. Level of ammonia in serum of experimental fish was markedly increased while excretion of ammonia by fish showed concomitant decrease. The bioaccumulation level of the pesticide and its degraded product, 3-hydroxy-carbofuran in liver tissue was measured by gas chromatography. A rationale of the effect of carbofuran on metabolism vis-a-vis toxicity in the fish has been suggested.