Some proteolytic properties of hatching liquid in the sea trout,Salmo trutta m. trutta L.

Proteolytic activity of sea trout hatching liquid was examined towards casein and azocazein as a function of pH and temperature. The optimum pH for caseinolytic and azocaseinolytic activities were 9.4, and 9.0, respectively. At alkaline pH the enzyme was activated by low concentrations of Zn²⁺ ions (10⁻⁵ M). Maximum proteolytic activity of the hatching liquid was observed at 25°C. Temperatures exceeding 30°C caused a rapid reduction in enzyme activity. Proteolytic activity observed at 10°C was approximately 50% of that observed at 25°C. In general, a pseudo-Arrhenius plot indicated a Q₁₀ of 1.6 between 6 and 25°C.     

Water quality affects SDH activity, protein content and RNA:DNA ratios in fish (Catla catla, Labeo rohita and Oreochromis mossambicus) raised in ponds of a sewage-fed fish farm

The spatial and seasonal variability of the respiratory enzyme succinate dehydrogenase and the protein content were examined in different tissues of fish cultured in three ponds along the effluent gradient of a sewage-fed fish farm. Indian major carp Catla catla (150-230 g) and Labeo rohita (60-190 g) cultured in both the middle and last points of the sewage effluent (stocking pond 1) and (stocking pond 4) and Oreochromis mossambicus (50-160 g), a naturally growing fish of the inlet (facultative pond) and the out let of the sewage effluent (stocking pond 4) were procured every month during the period of January-December, 2005 and were subjected to determination of succinate dehydrogenase activity, total protein, DNA and RNA contents from gill, liver and muscle tissue respectively. The SDH activity of all three test fishes (Catla catla, Labeo rohita and Oreochromis mossambicus) was reduced significantly (ANOVA; P < 0.05) when cultured in SP-4 compared to SP-1 in the case of Catla catla and Labeo rohita and in facultative pond in the case of Oreochromis mossambicus.Conspicuous differences in the SDH activity of fish between the last and first stocking pond or the facultative pond were clearly due to the result of the differences in water quality. There was a direct relationship between SDH activity in gill tissue of any of the fish investigated and ammonia-N concentration of water or water pH. This shows that the respiratory activity of these fishes was strongly affected by the ammonia and pH of water. In other words, this suggests that as the distance from the point source increases, there was a substantial improvement of water quality in the ponds located along the sewage effluent gradient. Evidently, there is a progressive pattern of growth, survival and physiological health of fish and abundance of favorable diversity of food organisms with rich biodiversity.     

Intestinal phytase I: Detection and preliminary characterization of activity in the intestinal brush border membrane of hybrid striped bass Morone saxatilis × M. chrysops

While numerous studies have evaluated intestinal phytase activity in terrestrial monogastric species, little work has been conducted investigating the enzyme's activity in finfish. This experiment was conducted to determine if hybrid striped bass Morone saxatilis × M. chrysops possess intestinal phytase activity, and to perform a preliminary characterization of this activity in terms of pH, metal ion dependence and substrate kinetics. Hybrid bass do exhibit low levels of intestinal phytase activity. The activity has an acidic pH optimum between 3.5 and 4.5. Low concentrations of Mn²⁺ slightly enhance this activity. The divalent cations Mg²⁺ and Zn²⁺ were shown to either have no effect on the enzyme activity or to be inhibitory, particularly at high concentrations. The present results indicate that intestinal phytase activity in hybrid bass does follow Michaelis-Menten kinetics, with estimated K_m and V_max values of 2.5 mM phytate and 4.8 units mg⁻¹ protein, respectively. The physiologic significance of the enzyme's presence in hybrid striped bass is questionable due to the low activity as compared to terrestrial monogastrics, the acidic pH optimum and the low affinity the enzyme appears to have for phytate. These observations also raise the question of whether the intestinal phytase activity detected in hybrid bass is merely a manifestation of non-specific acid phosphatase activity. Further investigation is needed to determine the practical significance of phytase activity in hybrid bass in terms of phytate phosphorus utilization. Additional experiments should also be conducted which evaluate intestinal phytase activity in other important aquacultured finfish species. This revised version was published online in July 2006 with corrections to the Cover Date.     

First Report of a Peroxiredoxin Homologue in Jellyfish: Molecular Cloning,Expression and Functional Characterization of CcPrx4 from Cyanea capillata

We first identified and characterized a novel peroxiredoxin (Prx), designated as CcPrx4, from the cDNA library of the tentacle of the jellyfish Cyanea capillata. The full-length cDNA sequence of CcPrx4 consisted of 884 nucleotides with an open reading frame encoding a mature protein of 247 amino acids. It showed a significant homology to peroxiredoxin 4 (Prx4) with the highly conserved F-motif (⁹³FTFVCPTEI¹⁰¹), hydrophobic region (²¹⁷VCPAGW²²²), ¹⁴⁰GGLG¹⁴³ and ²³⁹YF²⁴⁰, indicating that it should be a new member of the Prx4 family. The deduced CcPrx4 protein had a calculated molecular mass of 27.2 kDa and an estimated isoelectric point of 6.3. Quantitative real-time PCR analysis showed that CcPrx4 mRNA could be detected in all the jellyfish tissues analyzed. CcPrx4 protein was cloned into the expression vector, pET-24a, and expressed in Escherichia coli Rosetta (DE3) pLysS. Recombinant CcPrx4 protein was purified by HisTrap High Performance chelating column chromatography and analyzed for its biological function. The results showed that the purified recombinant CcPrx4 protein manifested the ability to reduce hydrogen peroxide and protect supercoiled DNA from oxidative damage, suggesting that CcPrx4 protein may play an important role in protecting jellyfish from oxidative damage.     

Four New Jacaranone Analogs from the Fruits of a Beibu Gulf Mangrove Avicennia marina

Four new jacaranone analogs, marinoids F–I (1–4), were isolated from the fruits of a Beibu Gulf mangrove Avicennia marina. The structures were elucidated based on analysis of spectroscopic data. Marinoids F and G are shown to be diastereoisomers of chlorocornoside, a new halogen containing marine secondary metabolite. The antioxidant activity of the isolates was evaluated using a cellular antioxidant assay, and 4 showed good antioxidant activity (EC₅₀ = 26 μM).     

Eunicellin-Based Diterpenoids,Hirsutalins N–R,from the Formosan Soft Coral Cladiella hirsuta

New eunicellin-type hirsutalins N–R (1–5), along with two known eunicellins, (6 and 7) were isolated from the soft coral Cladiella hirsuta. The structures of the metabolites were determined by extensive spectroscopic analysis. Cytotoxic activity of compounds 1–7 against the proliferation of a limited panel of cancer cell lines was measured. The in vitro anti-inflammatory activity of compounds 1–7 was evaluated by measuring their ability in suppressing superoxide anion generation and elastase release in fMLP/CB-induced human neutrophils.     

Quorum Quenching Agents: Resources for Antivirulence Therapy

The continuing emergence of antibiotic-resistant pathogens is a concern to human health and highlights the urgent need for the development of alternative therapeutic strategies. Quorum sensing (QS) regulates virulence in many bacterial pathogens, and thus, is a promising target for antivirulence therapy which may inhibit virulence instead of cell growth and division. This means that there is little selective pressure for the evolution of resistance. Many natural quorum quenching (QQ) agents have been identified. Moreover, it has been shown that many microorganisms are capable of producing small molecular QS inhibitors and/or macromolecular QQ enzymes, which could be regarded as a strategy for bacteria to gain benefits in competitive environments. More than 30 species of marine QQ bacteria have been identified thus far, but only a few of them have been intensively studied. Recent studies indicate that an enormous number of QQ microorganisms are undiscovered in the highly diverse marine environments, and these marine microorganism-derived QQ agents may be valuable resources for antivirulence therapy.     

谷特菌对青稞生长及土壤生态效应的影响

为了解生物肥对西藏青稞生长的影响,开展了谷特菌不同施用时期(播前、青稞拔节期),不同施用量对青稞产量影响的试验,供试生物肥为谷特菌,供试青稞品种为春青稞藏青320。在青稞收获期采样分析了青稞生物产量和经济产量,同时采集土样分析了土壤蔗糖酶、微生物量N等指标。结果表明:(1)施用谷特菌促进青稞分蘖,增加成穗数,在拔节期施用还能提高青稞灌浆能力,增加青稞穗粒数,提高青稞产量;(2)施用谷特菌对土壤0~10 cm土层蔗糖酶活性影响大,表现为土壤蔗糖酶活性随谷特菌施用量增加而增强,当施用量相同时,拔节期施用谷特菌导致土壤蔗糖酶活性增强,但对土壤微生物量N影响无统一规律。     

Effect of indaziflam on microbial activity and nitrogen cycling processes in an orchard soil

Indaziflam is a preemergent herbicide widely used for the control of weeds in pecan (Carya illinoinensis) orchards in the southwestern region of the United States. Given the paucity of data regarding the effect of indaziflam on the biochemical properties of soils supporting pecan production, this study was conducted to evaluate the effects of different application rates of indaziflam on soil microbial activity, diversity, and biochemical processes related to nitrogen (N) cycling. During two consecutive growing seasons (2015 and 2016), soil samples were obtained from experimental mesocosms consisting of soil-filled pots where pecan saplings were grown and treated with indaziflam applied at two different rates (25 and 50 g active ingredient (ai) ha^-1, with the higher rate being slightly lower than the recommended field application rate of 73.1 g ai ha^-1). Soil samples were collected approximately one week before and one week after herbicide application for determination of soil microbial biomass and diversity, N mineralization, and β-glucosaminidase activity. Soil samples collected from the control mesocosms without herbicide application were treated in the laboratory with two rates of indaziflam (75 and 150 g ai ha^-1) to determine the immediate effect on microbial activity. No significant effect of herbicide treatment on soil respiration and microbial biomass was detected. The results showed a slight to moderate decrease in microbial diversity (7% in 2015 and 44% in 2016). However, decreased β-glucosaminidase activity with herbicide treatment was observed in soils from the mesocosms (33%) and soils treated with indaziflam in the laboratory (45%). The mineral N pool was generally dominated by ammonium after indaziflam application, which was consistent with the drastic decrease (75%) in nitrification activity measured in the laboratory experiment. The results of this study indicate that indaziflam, even when applied at higher than recommended rates, has limited effects on soil microbial activity, but may affect N cycling processes.