Recent Advances of Genetic Resources,Genes and Genetic Approaches for Flooding Tolerance in Rice

Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world, which results in huge economic losses. The frequency and duration of flooding is predicted to increase in near future as a result of global climate change. Breeding of flooding tolerance in rice is a challenging task because of the complexity of the component traits, screening technique, environmental factors and genetic interactions. A great progress has been made during last two decades to find out the flooding tolerance mechanism in rice. An important breakthrough in submergence research was achieved by the identification of major quantitative trait locus (QTL) SUB1 in rice chromosomes that acts as the primary contributor for tolerance. This enabled the use of marker-assisted backcrossing (MABC) to transfer SUB1 QTL into popular varieties which showed yield advantages in flood prone areas. However, SUB1 varieties are not always tolerant to stagnant flooding and flooding during germination stage. So, gene pyramiding approach can be used by combining several important traits to develop new breeding rice lines that confer tolerances to different types of flooding. This review highlights the important germplasm/genetic resources of rice to different types of flooding stress. A brief discussion on the genes and genetic mechanism in rice exhibited to different types of flooding tolerance was discussed for the development of flood tolerant rice variety. Further research on developing multiple stresses tolerant rice can be achieved by combining SUB1 with other tolerance traits/genes for wider adaptation in the rain-fed rice ecosystems.     

Temporal activation of anti- and pro-apoptotic factors in human gingival fibroblasts infected with the periodontal pathogen, Porphyromonas gingivalis: potential role of bacterial proteases in host signalling

Background  

Porphyromonas gingivalis is the foremost oral pathogen of adult periodontitis in humans. However, the mechanisms of bacterial invasion and the resultant destruction of the gingival tissue remain largely undefined.     

Day length and evening temperature predict circannual variation in activity duration of the colony of the Indian cliff swallow,Hirundo fluvicola

In avian species, circannual rhythms, in a number of biological variables, including locomotor activity, have been studied under both laboratory and natural environmental conditions. However, information on circannual rhythm in daily activity duration of Indian cliff swallow (Hirundo fluvicola) is not available. It is a communal mud nesting, non-migratory species and inhabits low under arch bridges. Although it figures in the IUCN Red List under the least concerned category, it is important to study its behavioral ecology that may be of utmost importance from conservation stand point. In the present investigation, we examined the circannual rhythm in daily activity duration in this species at a communal roosting site under Kharoon river bridge on the Raipur–Bhilai highway (21°15′07.54′′N; 81°32′30.65′′E), Raipur, India, for eight consecutive days, every month from August 2009 to October 2011. On each study day, observations were made in two sessions, morning and evening. We monitored and recorded emergence time of the first bird from the nest in the morning and entry time of the last bird to the nest in the evening. We also recorded the ambient temperature and humidity of the study site simultaneously. Average daily activity duration (the time difference between the first bird’s emergence time and the last bird’s entry time from/to the nest, respectively) was computed for each month. A significant circannual rhythm in activity duration was validated. The peak of activity rhythm occurred on 22nd June with a spread between 19th June and 25th June. The activity duration was the shortest in winter and the longest in summer. The daily activity duration was positively correlated to the day length, sunset time, and morning and evening temperatures; whereas negatively correlated with the sunrise time, and morning and evening humidity. The multiple linear regression models suggest that day length alone explains 96% of the total variance in activity duration, whereas only 0.5% variance was attributable to evening temperature. We conclude that the day length is the strongest predictor of circannual variation in daily activity duration of the colony of Indian cliff swallow; whereas the evening temperature has very little effect. Further, we recommend that comparable studies under natural conditions might be very helpful to explore the effect of environmental cues on other intriguing behavioral decisions made by this and other avian species.     

Opercular Activity and Temporal Organization of Surfacing Behaviour in Indian Catfishes,Clarias batrachus and Heteropneustes fossilis

Opercular and surfacing activity were observed in the Indian catfish Clarias batrachus and Heteropneustes fossilis. In the series A experiments, the opercular activity was monitored under two experimental conditions, viz., (1) surfacing allowed and (2) surfacing prevented. A statistically significant elevation of the rate of opercular activity was observed when air breathing was prevented in both species. In addition, a significant prevention effect and a time of day dependence of that were noticed in both species. In the series B experiments, temporal patterns of surfacing and air-gulping activities were examined under an artificial LD 12:12 schedule at 2-h intervals over a period of 48 h. The inter air-gulping interval in minutes between two consecutive bouts was also recorded four times each day in both species. A significant 24-h rhythm was found for the rate of surfacing activity and length of the inter air-gulping interval in both species. However, the overall activity appears to be much higher in Heteropneustes fossilis as compared to Clarias batrachus.     

Theoretical exploration of the mechanism of formylmethanofuran dehydrogenase: the first reductive step in CO<Subscript>2</Subscript> fixation by methanogens

A theoretical exploration of the possible active site models of methanofuran dehydrogenase reveals that the free energy of the reduction of the carbamate group is substantially negative and is driven by the electron withdrawing amide group next to the carbonyl carbon. Comparison of the computed transition state energies with the experimental energy barrier indicates that the active site is likely to have an axial oxo and equatorial hydrosulfide ligand, the substrate is likely to be protonated and a second-sphere hydrogen-bonding interaction with the axial ligand can, substantially, lower the barrier of this reaction which involves reduction of the carbonyl center of the a carbamate to form an N-formyl group via a hydride shift from a Mo(IV) center.     

Assessment of Pulmonary Function in Young and Elderly Shift Workers of a Steel Plant

The present investigation was undertaken to examine the effects of shift work on pulmonary function. 217 subjects from a local steel plant, volunteered for this study. Of these, 65 were day workers (DWs) and 152 were shift workers (SWs). Pulmonary function, such as vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), peak expiratory flow rate (PEFR) and percent deviation of PEFR from the expected PEFR in each subject was measured between 09:00 to 11:00. Both day workers (DWs) and shift workers (SWs) were divided into two groups, based on age, i.e., ≤ 40 y and ≥ 41 y. The results indicate that the average levels of VC, FVC, FEV₁ and PEFR were significantly lower in older age in both DWs and SWs when compared to their younger counterparts. Although elderly shift workers had higher levels of VC, FVC and FEV₁ than day workers of comparable age, the difference was not statistically significant for FVC and FEV₁. In contrast, average value of PEFR was lower in older shift workers. Further, mean percent deviation of observed PEFR from the expected value was conspicuously low in elderly shift workers. In summary, shift work appears to accelerate age-related decline in PEFR at least in elderly shift workers. Results of multiple regression analysis and correlation analysis compliment this finding.