Unravelling the emerging threats of microplastics to agroecosystems

Reviews in Environmental Science and Bio/Technology - In the past few decades, pollution from microplastics has emerged as an important issue on a global scale. These plastic particles are mainly...     

Unraveling the camel rumen microbiome through metaculturomics approach for agriculture waste hydrolytic potential

Archives of Microbiology - Cellulose is the most abundant natural polymer present on Earth in the form of agriculture waste. Hydrolysis of agriculture waste for simple fermentable reducing sugars...     

Varying the length of dim nocturnal illumination differentially affects the pacemaker controlling the locomotor activity rhythm of Drosophila jambulina

Photic entrainment of animals in the field is basically attributed to their exposure to the dimly lit nights flanked by the dawn and dusk twilight transitions. This implicates the functional significance of the dimly lit nights as that of the twilight transitions. Recently, the authors have demonstrated that the dimly lit night at 0.0006 lux altered the attributes of the circadian rhythm of locomotor activity of Drosophila jambulina. The present study examined whether the durations of such dimly lit nights affect the entrainment and free-running rhythmicity of D. jambulina. Flies were subjected for 10 days to two types of 24-h lighting regimes in which the photophase (L) was at 10 lux for all flies but the scotophase, which varied in duration from 9 to 15 h, was either at 0 lux (D phase) for control flies or 0.0006 lux (the artificial starlight or S phase) for experimental flies. Thereafter, they were transferred to constant darkness (DD) to compare the after-effects of the dimly lit nights on the period (τ) of free-running rhythm in DD with that of the completely dark nights. Control flies were entrained by all LD cycles, but the experimental flies were entrained only by five LS cycles in which the duration of the S phases ranged from 10 to 14 h. The two LS cycles with very short (9 h) and long (15 h) S phases rendered the flies completely arrhythmic. Control flies started activity shortly before lights-on and continued well after lights-off. The experimental flies, however, commenced activity several hours prior to lights-on but ended activity abruptly at lights-off as the result of a negative masking effect of nocturnal illumination. Length of the midday rest was considerably shorter in the control than in the experimental flies in each lighting regime. The active phase in the control flies was predictably shortened; nonetheless, it was invariable in the experimental flies as the nights lengthened. Transfer from lighting regimes to DD initiated robust free-running rhythmicity in all flies including the arrhythmic ones subjected to LS cycles with 9 and 15 h of scotophases. The τ was profoundly affected by the nocturnal irradiance of the prior entraining lighting regime, as it was always shorter in the experimental than in the control flies. Thus, these results indisputably demonstrate the changes in fundamental properties of the circadian pacemaker of D. jambulina were solely attributed to the extremely dim nocturnal irradiance. This strain of D. jambulina is entrained essentially by the dimly lit natural nights, since it is never exposed to the prevailing photic cues such as the twilight transitions or bright photoperiod, owing to the dense vegetation of its habitat.     

Studies on Choanephoraceae. IV. Carbon requirements

Summary The comparative utilization of different carbon compounds byBlakeslea trispora, Choanephora cucurbitarum, Choanephora infundibulifera, Choanephora conjuncta, Choanephora heterospora andChoanephora circinans was studied under controlled conditions. Of the monosaccharides, rhamnose and sorbose were poorly utilized, while the rest of them were favourably utilized by all the species. Amongst the disaccharides, maltose proved to be the best. Sucrose, lactose and melibiose were poor sources. Raffinose, the only trisaccharide used supported poor growth of all the species. Of the polysaccharides used, starch and glycogen supported good growth of all the species. Dextrin and inulin were used in varying degrees by the present species. Both sorbitol and mannitol supported growth of the fungi in varying degrees. All the organic acids used, proved to be valueless in the present investigation.In some cases good sporulation was accompanied with good or moderate growth. No correlation with regard to the growth and sporulation could be established. The final pH of media showed a tendency to drift towards the alkaline side in most of the cases.     

Arabidopsis thaliana cdd1 mutant uncouples the constitutive activation of salicylic acid signalling from growth defects

Arabidopsis genotypes with a hyperactive salicylic acid-mediated signalling pathway exhibit enhanced disease resistance, which is often coupled with growth and developmental defects, such as dwarfing and spontaneous necrotic lesions on the leaves, resulting in reduced biomass yield. In this article, we report a novel recessive mutant of Arabidopsis, cdd1 (constitutive defence without defect in growth and development1), that exhibits enhanced disease resistance associated with constitutive salicylic acid signalling, but without any observable pleiotropic phenotype. Both NPR1 (NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1)-dependent and NPR1-independent salicylic acid-regulated defence pathways are hyperactivated in cdd1 mutant plants, conferring enhanced resistance against bacterial pathogens. However, a functional NPR1 allele is required for the cdd1-conferred heightened resistance against the oomycete pathogen Hyaloperonospora arabidopsidis. Salicylic acid accumulates at elevated levels in cdd1 and cdd1 npr1 mutant plants and is necessary for cdd1-mediated PR1 expression and disease resistance phenotypes. In addition, we provide data which indicate that the cdd1 mutation negatively regulates the npr1 mutation-induced hyperactivation of ethylene/jasmonic acid signalling.     

Complete genome sequence of Coraliomargarita akajimensis type strain (04OKA010-24)

Coraliomargarita akajimensis Yoon et al. 2007 is the type species of the genus Coraliomargarita. C. akajimensis is an obligately aerobic, Gram-negative, non-spore-forming, non-motile, spherical bacterium that was isolated from seawater surrounding the hard coral Galaxea fascicularis. C. akajimensis is of special interest because of its phylogenetic position in a genomically under-studied area of the bacterial diversity. Here we describe the features of this organism, together with the complete genome sequence, and annotation. This is the first complete genome sequence of a member of the family Puniceicoccaceae. The 3,750,771 bp long genome with its 3,137 protein-coding and 55 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

The determination of spatial pattern inDictyostelium discoideum

Free-living amoebae of the cellular slime mouldDictyostelium discoideum aggregate when starved and give rise to a long and thin multicellular structure, the slug. The slug resembles a metazoan embryo, and as with other embryos it is possible to specify a fate map. In the case ofDictyostelium discoideum the map is especially simple: cells in the anterior fifth of the slug die and form a stalk while the majority of those in the posterior differentiate into spores. The genesis of this anterior-posterior distinction is the subject of our review. In particular, we ask: what are the relative roles of individual pre-aggregative predispositions and post-aggregative position in determining cell fate? We review the literature on the subject and conclude that both factors are important. Variations in nutritional status, or in cell cycle phase at starvation, can bias the probability that an amoeba differentiates into a stalk cell or a spore. On the other hand, isolates, or slug fragments, consisting of only prestalk cells or only prespore cells can regulate so as to result in a normal range of both cell types. We identify three levels of control, each being responsible for guiding patterning in normal development: (i) ‘coin tossing’, whereby a cell autonomously exhibits a preference for developing along either the stalk or the spore pathway with relative probabilities that can be influenced by the environment; (ii) ‘chemical kinetics’, whereby prestalk and prespore cells originate from undifferentiated amoebae on a probabilistic basis but, having originated, interact (e.g. via positive and negative feedbacks), and the interaction influences the possibility of conversion of one cell type into the other; and (iii) ‘positional information’, in which the spatial distribution of morphogens in the slug influences the pathway of differentiation. In the case of possibilities (i) and (ii), sorting out of like cell types leads to the final spatial pattern. In the case of possibility (iii), the pattern arisesin situ