Length‐weight and length‐length relationships of three small indigenous fishes from the Payra River,southern Bangladesh

Length‐weight relationships (LWRs) and length‐length relationships (LLRs) for three small indigenous fishes (Esomus danrica, Pachypterus atherinoides and Salmostoma bacaila) were reported from the Payra River, southern Bangladesh. Samples were collected using traditional fishing gear including cast net (mesh size ranges from 1.0 to 2.0 cm), seine net (mesh size ranges from 1.5 to 2.5 cm) and square lift net (mesh size ~ 1.0 cm) in August to September 2017. Allometric coefficient (b) values were 2.66 for E. danrica, 3.08 for P. atherinoides and 3.06 for S. bacaila. The LLRs were also highly significant with r² ≥ .956.     

Reproductive biology of Apocryptes bato (Gobiidae) in the Payra River,southern Bangladesh

The gobioid fish Apocryptes bato (Hamilton, 1822) is a species of mudskipper found in Bangladesh, India, and Myanmar. The reproductive biology of A. bato including sex ratio, size at sexual maturity, breeding season, fecundity, and condition factor was studied in the Payra River, southern Bangladesh during May 2016 to April 2017. A total of 1,028 specimens (303 males and 725 females) were collected. The overall sex ratio was significantly different from the expected value of 1:1 (male: female = 1:2.39, χ² = 173.23, p < 0.05). Size at sexual maturity was estimated as 4.9 cm standard length. Monthly variations in gonadosomatic index indicate that the main breeding season is from May to December. There was a significant positive correlation of body length and body weight with fecundity. Fulton's condition factor varied in both sexes and was attributed to variations in GSI with maturity. Breeding season was significantly associated with rainfall, but not air temperature. Our findings should improve management and conservation of this fish in the Payra River and surrounding ecosystems.     

Zinc deficiency tolerance in maize is associated with the up‐regulation of Zn transporter genes and antioxidant activities

• Zinc (Zn) is an essential micronutrient for the growth and development of plants. However, Zn deficiency is a common abiotic stress causing yield loss in crop plants. This study elucidates the mechanisms of Zn deficiency tolerance in maize through physiological and molecular techniques.
• Maize lines tolerant (PAC) and sensitive (DAC) to Zn deficiency were examined physiologically and by atomic absorption spectrometry (AAS). Proteins, H₂O₂, SOD, POD, membrane permeability and gene expression (using real‐time PCR) of roots and shoots of both maize lines were assessed.
• Zn deficiency had no significant effect on root parameters compared with control plants in PAC and DAC but showed a substantial reduction in shoot parameters in DAC. AAS showed a significant decrease in Zn concentrations in both roots and shoots of DAC but not PAC under Zn deficiency, implying that Zn deficiency tolerance mechanisms exist in PAC. Consistently, total protein and membrane permeability were significantly reduced in DAC but not PAC in both roots and shoots under Zn deficiency in comparison with Zn‐sufficient plants. Real‐time PCR showed that expression of ZmZIP1, ZmZIP4 and ZmIRT1 transporter genes significantly increased in roots of PAC, but not in DAC due to Zn deficiency compared with controls. The H₂O₂ concentration dramatically increased in roots of DAC but not PAC. Moreover, tolerant PAC showed a significant increase in POD and SOD activity due to Zn deficiency, suggesting that POD‐ and SOD‐mediated antioxidant defence might provide tolerance, at least in part, under Zn deficiency in PAC.
• This study provides an essential background for improving Zn biofortification of maize.

     

Assessing antigen specific HLA-DR+ antibody secreting cell (DR+ASC) responses in whole blood in enteric infections using an ELISPOT technique

Antibody secreting cells (ASCs) generate antibodies in an antigen-specific manner as part of the adaptive immune response to infections, and these cells increase their surface expression of HLA-DR. We have studied this parameter (HLA-DR+ ASC) in patients with recent diarrheal infection using immuno-magnetic cell sorting and an enzyme linked immunospot (ELISPOT) technique that requires only one milliliter of blood. We validated this approach in adult patients with cholera (n = 15) or ETEC diarrhea (n = 30) on days 2, 7 and 30 after showing clinical symptom at the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) hospital in Dhaka, and we compared responses to age-matched healthy controls (n = 7). We found that HLA-DR+ ASC (DR+ASC) responses specific both for T cell-dependent (cholera toxin B subunit), and T cell-independent (lipopolysaccharide) antigens were elevated at day 7 after showing clinical cholera symptom. Similarly, DR+ASCs were elevated against both heat-labile toxin and colonization factors following ETEC infection. We observed significant correlations between antigen-specific DR+ASC responses and antigen-specific, gut homing ASC and plasma antibody responses. This study demonstrates that a simple ELISPOT procedure allows determination of antigen-specific ASC responses using a small volume of whole blood following diarrhea. This technique may be particularly useful in studying DR+ASC responses in young children and infants, either following infection or vaccination.     

PCR amplification of DNA sequence related to the hrpD gene of Xanthomonas cucurbitae in leaf spot disease of pumpkin and their antagonism by soil bacteria

A sensitive and specific assay was developed to detect and biological control of bacterial leaf spot of pumpkin, Xanthomonas cucurbitae was identified on the basis of the morphological, biochemical and molecular assay. The antibiotic sensitivity of the isolate showed that, Carbenicillin revealed highest antibacterial activity with 29 ± 0.00 mm zone of inhibition against isolated bacterial strain. Isolated bacterial strains from soil were also identified by biochemical and molecular characterisation. By analysing morphological and biochemical characteristics and 16S rDNA of three bacterial strains isolated from soil was matched 96% with Bacillus subtilis, 98% with Bacillus brevis and 97% with Pseudomonas fluorescens strain. They were subjected to the antagonistic activity against Xanthomonas cucurbitae by disc diffusion method. Among them, B. subtilis showed significant positive antagonistic activity with 17.0 ± 0.28 mm zone of inhibition against Xanthomonas cucurbitae. The presence of DNA sequence related to the hrpD gene successfully amplified in some isolates of Xanthomonas cucurbitae.     

Association of nitrogen-fixing,plant-growth-promoting rhizobacteria (PGPR) with kallar grass and rice

Leptochloa fusca (L.) Kunth (kallar grass) has previously been found to exhibit high rates of nitrogen fixation. A series of experiments to determine the level of biological nitrogen fixation using N isotopic dilution were carried out in nutrient solution and saline soil. These studies indicated an agronomically significant amount of nitrogen being fixed in soil. Kallar grass has a similar growth habitat to rice. Therefore similar studies were carried out with rice after isolating various diazotrophs from the roots which were also screened for their ability to produce auxin (IAA). Five such strains namely Azospirillum lipoferum N-4, Azospirillum brasilense Wb-3, Azoarcus K-1, Pseudomonas 96-51, Zoogloea Ky-1 were selected for inoculating two rice varieties i.e. NIAB-6 and BAS-370 under aseptic laboratory conditions. The nitrogen fixed was quantified using the N isotopic dilution method. Variety BAS-370 had nearly 70% nitrogen derived from atmosphere (Ndfa) when inoculated with Azospirillum N-4. Similar studies with the mixed inoculum using N fertilizer in the micro plots indicated that nearly 29% of plant nitrogen was derived from the atmosphere.     

Glyoxal and methylglyoxal trigger distinct signals for map family kinases and caspase activation in human endothelial cells.

Carbonyl compounds with diverse carbon skeletons may be differentially related to the pathogenesis of vascular diseases. In this study, we compared intracellular signals delivered into cultured human umbilical vein endothelial cells (HUVECs) by glyoxal (GO) and methylglyoxal (MGO), which differ only by a methyl group. Depending on their concentrations, GO and MGO promoted phosphorylations of ERK1 and ERK2, which were blocked by the protein-tyrosine kinase (PTK) inhibitors herbimycin A and staurosporine, thereby being PTK-dependent. GO and MGO also induced phosphorylations of JNK, p38 MAPK, and c-Jun, either PTK-dependently (GO) or -independently (MGO). Next, we found that MGO, but not GO, induced degradation of poly(ADP-ribose) polymerase (PARP) as the intracellular substrate of caspase-3. Curcumin and SB203580, which inhibit JNK and p38 MAPK signaling pathways, but not herbimycin A/staurosporine, prevented the MGO-induced PARP degradation. We then found that MGO, but not GO, reduced the intracellular glutathione level, and that cysteine, but not cystine, inhibited the MGO-mediated activation of ERK, JNK, p38 MAPK, or c-Jun more extensively than did lysine or arginine. In addition, all the signals triggered by GO and MGO were blocked by amino guanidine (AG), which traps carbonyls. These results demonstrated that GO and MGO triggered two distinct signal cascades, one for PTK-dependent control of ERK and another for PTK-independent redox-linked activation of JNK/p38 MAPK and caspases in HUVECs, depending on the structure of the carbon skeleton of the chemicals.     

Cyclodecapeptides to mimic the radical site of tyrosyl-containing proteins.

Tyrosyl radicals are involved in many biologically important processes. The development of model compounds to mimic radical enzyme active sites, such as galactose oxidase (GO), has widely contributed to an enhanced understanding of their spectral properties, structural attributes and even reactivity. An emerging approach towards the synthesis of such active site mimetics is the use of peptidic ligands. The potential of cyclodecapeptides to bear phenoxyl radicals has been evaluated through three compounds. LH(4) (2+) is a cyclodecapetide containing two histidine residues (mimicking His(496) and His(581) of GO) and two tyrosine residues (mimicking Tyr(495) and the Tyr(272)* radical of GO). L(tBu)H(4) (2+) and L(OMe)H(4) (2+) incorporate 2,4,6-protected phenols in place of each tyrosine in LH(4) (2+). The deprotonation constants of each peptide determined by potentiometric titrations showed that there are some interactions between the acido-basic residues. Cyclic voltammetric studies revealed that only the peptides incorporating 2,4,6-protected phenolates exhibit reversible redox couples and are thus precursors of radicals stable enough to persist in solution. These studies also showed L(OMe2-) to possess the lower oxidation potential, indicating that this peptide, in its radical form, is the most stabilized. The electrochemically generated radical species have been characterized by EPR spectroscopy.     

Clonal crayfish as biological model: a review on marbled crayfish

Since the mid-twentieth century, numerous vertebrates and invertebrates have been used as model organisms and become indispensable tools for exploring a broad range of biological and ecological processes. Crayfish seem to be adequate models which resulted in their involvement in research. In the two decades since its discovery, ongoing research has confirmed that the marbled crayfish (Procambarus virginalis Lyko, 2017) is an ideal taxon in this regard, especially due to its almost continuous asexual reproduction providing a source of genetically identical offspring. This review provides an overview of the occurrence, biology, ecology, ethology, and human exploitation of marbled crayfish with primary focus on its use as a laboratory model organism as well as potential risks to native biota in case of its introduction. Genetic uniformity, ease of culture, and a broad behaviour repertoire fosters the use of marbled crayfish in epigenetics and developmental biology, as well as physiological, ecotoxicological, and ethological research. Marbled crayfish could be further exploited for basic and applied fields of science such as evolutionary biology and clonal tumour evolution. However, due to its high invasive potential in freshwater environments security measures must be taken to prevent its escape into the wild.     

Manganese-induced salt stress tolerance in rice seedlings: regulation of ion homeostasis,antioxidant defense and glyoxalase systems

Hydroponically grown 12-day-old rice (Oryza sativa L. cv. BRRI dhan47) seedlings were exposed to 150 mM NaCl alone and combined with 0.5 mM MnSO₄. Salt stress resulted in disruption of ion homeostasis by Na⁺ influx and K⁺ efflux. Higher accumulation of Na⁺ and water imbalance under salinity caused osmotic stress, chlorosis, and growth inhibition. Salt-induced ionic toxicity and osmotic stress consequently resulted in oxidative stress by disrupting the antioxidant defense and glyoxalase systems through overproduction of reactive oxygen species (ROS) and methylglyoxal (MG), respectively. The salt-induced damage increased with the increasing duration of stress. However, exogenous application of manganese (Mn) helped the plants to partially recover from the inhibited growth and chlorosis by improving ionic and osmotic homeostasis through decreasing Na⁺ influx and increasing water status, respectively. Exogenous application of Mn increased ROS detoxification by increasing the content of the phenolic compounds, flavonoids, and ascorbate (AsA), and increasing the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), superoxide dismutase (SOD), and catalase (CAT) in the salt-treated seedlings. Supplemental Mn also reinforced MG detoxification by increasing the activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) in the salt-affected seedlings. Thus, exogenous application of Mn conferred salt-stress tolerance through the coordinated action of ion homeostasis and the antioxidant defense and glyoxalase systems in the salt-affected seedlings.