Restriction enzyme analysis of plant genomes

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Short period variations of the aerosol mass concentrations over Bay of Bengal: association with quasi-periodic variations in the marine atmospheric boundary layer parameters and fluxes

Analysis of the time-series of daily mean total aerosol mass concentrations (M_T), measured within the Marine Atmospheric Boundary Layer (MABL) over the Bay of Bengal (BoB) revealed the presence of short-period modulations with periods of 4–6 days, 8–10 days as well as quasi 16-day (14–20 days). These were found to be distinctively associated with similar oscillations in the concurrently measured MABL parameters such as air temperature (AT), pressure (P), relative humidity (RH), wind speed (WS), sea surface temperature (SST) and derived parameters such as Momentum Flux (MF), Latent Heat Flux (LHF) and Sensible Heat Flux (SHF). Examination of the phase relations revealed that the 4–6 days and quasi 16-day periodicities in AT, P, RH and SST maintained a nearly in-phase (very small phase difference <±20°) variation between themselves and also with similar periodicities in the aerosol mass concentration MT. On the other hand, the periodicities in WS, SHF, LHF and MF, though were nearly in-phase among themselves, exhibited an out-of-phase (phase difference 180±20°) relation with that of M_T. Interestingly, the 8–10 day periodicities revealed a different phase relationship; the variables AT, P, SST, WS and M_T> were in-phase and these variables were out-of-phase with similar periodicities in RH and the fluxes. It was also observed that all the three waves represented westward propagating Rossby waves. An easterly phase in the wind was found to result in advection of particles from the East Asia to BoB, as evident from the out-of-phase relationship between the periodicities of 4–6 days and quasi 16-day in M_T and zonal wind. The meridional component, that was stronger than its zonal amplitude in the 8–10 day periodicity, resulted in enhanced advection of particles from the southern part of Bay of Bengal in comparison with that from the Eastern region, leading to an in-phase relationship between M_T and zonal wind

Diurnal variations of the low-level jet over peninsular India during the onset of Asian summer monsoon

The evidence for diurnal variation of monsoon low-level jet (MLLJ) over the southern tip of India is illustrated from observations, a mesoscale model results, and long-term reanalysis products. This illustration showed that MLLJ has a diurnal variation in its strength and location of maxima. Diurnal signature of MLLJ is not found to be location-specific. Stronger jets are formed at a lower elevation during the nighttime, and the jets are weaker during the day but are higher elevated. During the daytime, a secondary jet is also observed along with the MLLJ. Both the jets were numerically simulated during the onset phase of southwest monsoon over the southwest coast of India. Thirty-year climatological analysis from Modern Era Retrospective analysis for Research and Applications (MERRA) showed that the secondary jet is shallow and weak during the pre-onset phase of monsoon. With the progress of monsoon, the MLLJ gets stronger with increased wind speed and elevated location of its core. In occasions where the jet is strong before the onset, the strongest jets proceed after the onset. Daytime MLLJ is higher elevated compared to the nocturnal MLLJ due to the frictional decoupling

A Possible Mechanism of Zika Virus Associated Microcephaly: Imperative Role of Retinoic Acid Response Element (RARE) Consensus Sequence Repeats in the Viral Genome.

Owing to the reports of microcephaly as a consistent outcome in the foetuses of pregnant women infected with ZIKV in Brazil, Zika virus (ZIKV) - microcephaly etiomechanistic relationship has recently been implicated. Researchers, however, are still struggling to establish an embryological basis for this interesting causal handcuff. The present study reveals robust evidence in favour of a plausible ZIKV-microcephaly cause-effect liaison. The rationale is based on: (1) sequence homology between ZIKV genome and the response element of an early neural tube developmental marker ‘retinoic acid’ in human DNA and (2) comprehensive similarities between the details of brain defects in ZIKV-microcephaly and retinoic acid embryopathy. Retinoic acid is considered as the earliest factor for regulating anteroposterior axis of neural tube and positioning of structures in developing brain through retinoic acid response elements (RARE) consensus sequence (5′–AGGTCA–3′) in promoter regions of retinoic acid-dependent genes. We screened genomic sequences of already reported virulent ZIKV strains (including those linked to microcephaly) and other viruses available in National Institute of Health genetic sequence database (GenBank) for the RARE consensus repeats and obtained results strongly bolstering our hypothesis that ZIKV strains associated with microcephaly may act through precipitation of dysregulation in retinoic acid-dependent genes by introducing extra stretches of RARE consensus sequence repeats in the genome of developing brain cells. Additional support to our hypothesis comes from our findings that screening of other viruses for RARE consensus sequence repeats is positive only for those known to display neurotropism and cause foetal brain defects (for which maternal-foetal transmission during developing stage may be required). The numbers of RARE sequence repeats appeared to match with the virulence of screened positive viruses. Although bioinformatic evidence and embryological features are in favour of our hypothesis, additional studies including animal models are warranted to validate our proposition. Such studies are likely to unfold ZIKV-microcephaly association and may help in devising methods to combat it

Vertical profiles of aerosol black carbon in the atmospheric boundary layer over a tropical coastal station: perturbations during an annular solar eclipse

Altitude profiles of aerosol black carbon (BC) in the atmospheric boundary layer (ABL) over a tropical coastal station, Trivandrum have been examined on two days using an aethalometer attached to a tethered balloon. One of these days (15th January, 2010) coincided with a (annular) solar eclipse, the longest of this century at this location, commenced at 11:05 local time and ended by 15:05, lasting for 7 min and 15 s (from 13:10:42), with its maximum contact occurring at ~ 13:14 IST with ~ 92% annularity, thereby providing an opportunity to understand the eclipse induced perturbations. Concurrent measurements of the ABL parameters such as air temperature, relative humidity and pressure were also made on these days to describe the response of the ABL to the eclipse. BC profiles, in general, depicted similar features up to an altitude of ~ 200 m on the eclipse day and control day, above which it differed conspicuously with profiles on eclipse day showing increasingly lower concentration as we moved to higher altitudes. Examination of the meteorological profiles showed that the altitude of maximum convection rapidly fell down during the eclipse period compared to that on control day indicating a rather shallow convection on eclipse day. Comparison of diurnal variations of BC at the surface level showed that the rate of decrease in BC during daytime on the eclipse day was smaller than that on the control day due to the reduced convection, shallow ABL and consequent reduction in the ventilation coefficient. Moreover the time of the nocturnal increase has advanced by ~ 1:30 h on the eclipse day, occurred at around 19:30 IST in contrast to all the other days of January 2010, where this increase usually occur well after 20:30 IST, with a mean value of 21:00 IST. This is attributed to the weak sea-breeze penetration during the eclipse day, which led to an early onset of the land breeze