Feeding behaviour of generalist pests on Brassica juncea: implication for manipulation of glucosinolate biosynthesis pathway for enhanced resistance

Differential accumulation of plant defence metabolites has been suggested to have important ecological consequence in the context of plant–insect interactions. Feeding of generalist pests on Brassica juncea showed a distinct pattern with selective exclusion of leaf margins which are high in glucosinolates. Molecular basis of this differential accumulation of glucosinolates could be explained based on differential expression profile of BjuMYB28 homologues, the major biosynthetic regulators of aliphatic glucosinolates, as evident from quantitative real‐time PCR and promoter:GUS fusion studies in allotetraploid B. juncea. Constitutive overexpression of selected BjuMYB28 homologues enhanced accumulation of aliphatic glucosinolates in B. juncea. Performance of two generalist pests, Helicoverpa armigera and Spodoptera litura larvae, on transgenic B. juncea plants were poor compared to wild‐type plants in a no‐choice experiment. Correlation coefficient analysis suggested that weight gain of H. armigera larvae was negatively correlated with gluconapin (GNA) and glucobrassicanapin (GBN), whereas that of S. litura larvae was negatively correlated with GNA, GBN and sinigrin (SIN). Our study explains the significance and possible molecular basis of differential distribution of glucosinolates in B. juncea leaves and shows the potential of overexpressing BjuMYB28 for enhanced resistance of Brassica crops against the tested generalist pests.     

Dominant fungi in the rhizosphere of established tea bushes and their interaction with the dominant bacteria under in situ conditions

Species of Penicillium and Trichoderma were found to dominate the rhizosphere of established tea bushes in a detailed study conducted from various tea growing locations in India. Penicillium erythromellis, P. janthinellum, P. raistrickii, Trichoderma pseudokoningii and T. koningii were found to be closely associated with tea roots. While seasonal fluctuation was observed in the case of Penicillium spp., the population of Trichoderma spp. showed less variation during the year. Both species were sensitive to low temperatures. In general, fungi associated with the tea rhizosphere were found to prefer a mesophillic temperature range (15 °C to 35 °C). The dominant species of Penicillium and Trichoderma also exhibited tolerance to lower temperatures, i.e., 5 to 10 °C on agar plates. Most fungi were able to grow in a wide range of pH (4 to 12). Lowering of soil pH in the rhizosphere of tea bushes was positively correlated with the age of the bush and may have affected the development of a specific microbial community in the rhizosphere.The populations of Penicillium and Trichoderma species were inversely correlated with the populations of two most dominant rhizosphere bacteria, Bacillus subtilis and B. mycoides. Both Bacillus species have been shown to have antagonistic activity against these two fungi under in vitro conditions. The present study demonstrates the existence of a similar antagonism under in situ conditions in the rhizosphere of established tea bushes.     

Mycotoxigenic infestation in samples of cereal straw from Bihar, India

A survey of different types of cereal straw samples viz. paddy, maize and wheat, from Bihar State, India, was conducted in order to examine the mould flora and mycotoxin contamination. Out of 170 samples examined for mould flora,Aspergillus flavus group of fungi had highest level of incidence followed byA niger. Isolates ofA flavus, A ochraceus, Fusarium verticillioides andPenicillium citrinum were screened for their mycotoxins producing abilities. Out of 75, 63 and 68 isolates ofA flavus group obtained from stored straw of paddy, maize and wheat samples, respectively, 27 (36%), 14 (22%) and 24 (35%) were found to be toxigenic which produced different combinations of aflatoxins in different concentrations. The percentage toxigenicity was comparatively lower in the isolates of other mycotoxigenic fungi from all types of samples. Out of 222 samples of straw analysed for natural occurrence of different mycotoxins, besides the aflatoxins present, zearalenone, ochratoxin A and citrinin were also recorded alone or as co-contaminants. A conducive climate together with the socioeconomic conditions of this region are important determinants for the high incidence of mycotoxins in cereal straw samples.     

GDP-mannose-4,6-dehydratase is a cytosolic partner of tankyrase 1 that inhibits its poly(ADP-ribose) polymerase activity

Tankyrase 1 is a poly(ADP-ribose) polymerase (PARP) that participates in a broad range of cellular activities due to interaction with multiple binding partners. Tankyrase 1 recognizes a linear six-amino-acid degenerate motif and, hence, has hundreds of potential target proteins. Binding of partner proteins to tankyrase 1 usually results in their poly(ADP-ribosyl)ation (PARsylation) and can lead to ubiquitylation and proteasomal degradation. However, it is not known how tankyrase 1 PARP activity is regulated. Here we identify GDP-mannose 4,6-dehydratase (GMD) as a binding partner of tankyrase 1. GMD is a cytosolic protein required for the first step of fucose synthesis. We show that GMD is complexed to tankyrase 1 in the cytosol throughout interphase, but its association with tankyrase 1 is reduced upon entry into mitosis, when tankyrase 1 binds to its other partners TRF1 (at telomeres) and NuMA (at spindle poles). In contrast to other binding partners, GMD is not PARsylated by tankyrase 1. Indeed, we show that GMD inhibits tankyrase 1 PARP activity in vitro, dependent on the GMD tankyrase 1 binding motif. In vivo, depletion of GMD led to degradation of tankyrase 1, dependent on the catalytic PARP activity of tankyrase 1. We speculate that association of tankyrase 1 with GMD in the cytosol sequesters tankyrase 1 in an inactive stable form that can be tapped by other target proteins as needed.     

A Review on Potential Footprints of Ferulic Acid for Treatment of Neurological Disorders

Ferulic acid is being screened in preclinical settings to combat various neurological disorders. It is a naturally occurring dietary flavonoid commonly found in grains, fruits, and vegetables such as rice, wheat, oats, tomatoes, sweet corn etc., which exhibits protective effects against a number of neurological diseases such as epilepsy, depression, ischemia-reperfusion injury, Alzheimer’s disease, and Parkinson’s disease. Ferulic acid prevents and treats different neurological diseases pertaining to its potent anti-oxidative and anti-inflammatory effects, beside modulating unique neuro-signaling pathways. It stays in the bloodstream for longer periods than other dietary polyphenols and antioxidants and easily crosses blood brain barrier. The use of novel drug delivery systems such as solid-lipid nanoparticles (SLNs) or its salt forms (sodium ferulate, ethyl ferulate, and isopentyl ferulate) further enhance its bioavailability and cerebral penetration. Based on reported studies, ferulic acid appears to be a promising molecule for treatment of neurological disorders; however, more preclinical (in vitro and in vivo) mechanism-based studies should be planned and conceived followed by its testing in clinical settings.

     

Biliverdin modulates the expression of C5aR in response to endotoxin in part via mTOR signaling

Macrophages play a crucial role in the maintenance and resolution of inflammation and express a number of pro- and anti-inflammatory molecules in response to stressors. Among them, the complement receptor 5a (C5aR) plays an integral role in the development of inflammatory disorders. Biliverdin and bilirubin, products of heme catabolism, exert anti-inflammatory effects and inhibit complement activation. Here, we define the effects of biliverdin on C5aR expression in macrophages and the roles of Akt and mammalian target of rapamycin (mTOR) in these responses. Biliverdin administration inhibited lipopolysaccharide (LPS)-induced C5aR expression (without altering basal expression), an effect partially blocked by rapamycin, an inhibitor of mTOR signaling. Biliverdin also reduced LPS-dependent expression of the pro-inflammatory cytokines TNF-α and IL-6. Collectively, these data indicate that biliverdin regulates LPS-mediated expression of C5aR via the mTOR pathway, revealing an additional mechanism underlying biliverdin’s anti-inflammatory effects.     

Homologies of the adductor mandibulae muscles in Tetraodontiformes as indicated by nerve branching patterns

Homologies of the adductor mandibulae muscles in eight families of Tetraodontiformes were hypothesized from the branching patterns of ramus mandibularis trigeminus. Insertions of the muscles to the upper or lower jaw were weak indicators of homology, migrations of the sites occurring frequently in A1, A2, A2, and A3. In monacanthids, tetraodontids, and diodontids, A1 tended to be split into numerous subsections, whereas in aracanids and ostraciids, A3 was highly developed, comprising three or four subsections. In tetraodontids, A2 was found to be a composite of A1 subsection and A2. The methods of and limits to applying nerve branching patterns to muscle homology are discussed. A new naming system that reflects both muscle homologies and insertions is proposed.     

Seasonal histological changes in the ovaries of a mountain stream teleost, Schizothorax richardsonii (Gray and Hard).

In S. richardsonii, unlike its testis, the whole of the ovary is fertile. The oogonia pass through seven maturation stages to form the ripe ova. The residual oogonia are responsible for the development of the new crop of oogonia. The zonation of the ooplasm reveals that a majority of the oocytes have a darkly stained inner and a lightly stained outer zone. The yolk nucleus probably has some relationship with the process of vitellogenesis. The nucleoli are produced by the division and fragmentation of the nucleolus. Extrusion of nucleoli appears to be associated with the formation of yolk. The formation of yolk globules in the oocyte begins in the periphery of the ooplasm and moves inward till the whole of the ooplasm in impregnated with yolk. As the yolk vesicles are PAS-positive in this fish, they contain mucopolysaccharides. The ovarian cycle can be divided into five stages. The ovary becomes much enlarged and distended in the month of October and delicate and thin in March. The spawning season extends from late October to December and the ovary exhibits asynchronism.     

Synergistic effects of short peptides and antibiotics against bacterial and fungal strains

There is a rising tide of concern about the antibiotic resistance issue. To reduce the possibility of antibiotic-resistant infections, a new generation of antimicrobials must be developed. Antimicrobial peptides are potential alternatives to antibiotics that can be used alone or together with conventional antibiotics to combat antimicrobial resistance. In this work, lead compounds LP-23, DP-23, SA4, and SPO from previously published studies were synthesized by solid-phase peptide synthesis and their antimicrobial evaluation was carried out against various bacterial and fungal strains. Peptide combinations with antibiotics were evaluated by using the checkerboard method and their minimal inhibitory concentration (MIC) in combination was calculated by using the fractional inhibitory concentration (FIC) index. Cytotoxicity evaluations of these peptides further confirmed their selectivity toward microbial cells. Based on the FIC values, LP-23, DP-23, and SPO demonstrated synergy in combination with gentamicin against a gentamicin-resistant clinical isolate of Escherichia coli. For Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium, seven combinations exhibited synergistic effects between peptide/peptoids and the tested antibiotics. Additionally, almost all the combinations of peptides/peptoids with amphotericin B and fluconazole also showed effective synergy against Aspergillus niger and Aspergillus flavus. The synergy found between LP-23, DP-23, SA4, and SPO with the selected antibiotics may have the potential to be used as a combination therapy against various microbial infections.     

Short-day experience is not a prerequisite for the termination of photorefractoriness in the reproductive cycle of baya weaver,Ploceus philippinus

In most photoperiodic avian forms (irrespective of temperate or tropical distribution) including the baya weaver,Ploceus philippinus, seasonal reproduction comes to an end due to the development of a photoperiodically controlled photorefractory phase when birds cease to respond to the stimulatory effect of long days. In the present paper photoperiodic control of the termination of photorefractory phase has been examined by studying the effect of short-day exposure lasting 4–6 months on long-day response of birds. Results indicate that unlike in other photoperiodic birds short-day exposure of winter is not a prerequisite for the termination of photorefractory phase in the reproductive cycle of baya weaver. Artificial long days on the other hand hasten the termination of this phase. Refractory phase in baya weaver, therefore, unlike that in temperate forms, is a temporary state resulting most likely from a sequel of physiological events triggered by long days of spring/summer which temporarily mask the photostimulatory response. Spontaneous termination of photorefractoriness in birds of tropical habitats may have a selective value imparting to the reproductive cycle the necessary elasticity for adaptation to diverse ecological conditions.