Autoradiographic study of kinetics of spermatogenesis in Ascaris lumbricoides

The kinetics of meiosis and spermiogenesis in Ascaris lumbricoides in vitro was studied by keeping 12 mature males in nutrient medium. The spermatocytes were made radioactive by supplementing the medium with 3H-thymidine for 2 h, following which they were transferred to fresh medium without 3H-TdR. The nematodes were then killed for preparing histological and squash preparations of the testis. An analysis of the migration of "hot" spermatocytes till the formation of mature spermatozoa, in Kodak AR-10 autoradiograms, suggested that the duration of meiosis and spermiogenesis was a little more than 5.5 and 7.6 days, respectively. The total duration of these two events was about 13.1 days when radioactive spermatozoa were detected for the first time.     

Rapid and Differential Proliferation of the Ty3-Gypsy LTR Retrotransposon Atlantys in the Genus Oryza

Here, we present the results of a comprehensive study of the distribution, evolution, heterogeneity, and phylogenetic relationships of the Ty3-Gypsy Atlantys long terminal repeat retrotransposable element family in Oryza. Atlantys element-related sequences make up a significant fraction of the genomes of species from the Officinalis complex as well as the Oryza ridleyi and O. granulata genomes. The proliferation of Atlantys elements, in many cases, took place after respective speciation events occurred. Most of the retrotranspositional events occurred within the last three million years. Atlantys is an ancient and ubiquitous component of the genus Oryza and has made significant contributions to genome size variation across the genus. Its structure is unusual when compared to other Ty3-Gypsy elements and its proliferation in the different Oryza species has been rapid and differential.     

SOIL CO2 FLUX IN GRASSLAND,AFFORESTED LAND AND RECLAIMED COALMINE OVERBURDEN DUMPS: A CASE STUDY

The aim of this study was to measure the in situ soil CO₂ flux from grassland, afforested land and reclaimed coalmine overburden dumps by using the automated soil CO₂ flux system (LICOR‐8100® infrared gas analyzer, LICOR Inc., Lincoln, NE). The highest soil CO₂ flux was observed in natural grassland (11·16 µmol CO₂ m⁻²s⁻¹), whereas the flux was reduced by 38 and 59 per cent in mowed site and at 15‐cm depth, respectively. The flux from afforested area was found 5·70 µmol CO₂ m⁻²s⁻¹, which is 50 per cent lower than natural grassland. In the reclaimed coalmine overburden dumps, the average flux under tree plantation was found to be lowest in winter and summer (0·89–1·12 µmol CO₂ m⁻²s⁻¹) and highest during late monsoon (3–3·5 µmol CO₂ m⁻²s⁻¹). During late monsoon, the moisture content was found to be higher (6–7·5 per cent), which leads to higher microbial activity and decomposition. In the same area under grass cover, soil CO₂ flux was found to be higher (8·94 µmol CO₂ m⁻²s⁻¹) compared with tree plantation areas because of higher root respiration and microbial activity. The rate of CO₂ flux was found to be determined predominantly by soil moisture and soil temperature. Our study indicates that the forest ecosystem plays a crucial role in combating global warming than grassland; however, to reduce CO₂ flux from grassland, mowing is necessary. Copyright © 2012 John Wiley & Sons, Ltd.     

The structural configuration and stretch property relationship of high stretch bandage fabric

The high compression bandages need to be designed or selected based on their ability to apply high levels of pressure with minimum stretch and maintain the same over a period of time. This can be achieved if the factors controlling this behaviour are optimised to get the desired performance. The efficiency of different bandages to provide sustained pressure varies because of differences in their structure and constituent material type as the fibre type, yarn structure and the structure of the bandage. In this paper the structure and stretch relationship of different high compression bandage materials have been studied which would help to design and evaluate the bandage performance during and after application on the limb. The influence of structure of the bandage in terms of design pattern/weave, linear density and number of inlaid elastic yarn in the high stretch bandages along with their mechanical behaviour has been investigated. It has been found that different bandages although commercially sold under the category of high compression bandages show quite varied tensile and relaxation behaviour depending on their structure and constructional parameters. The bandage sample with coarser high elastic yarns show low fabric growth, high breaking load and high elastic recovery values. The presence of higher number of high stretch inlay yarns and a tighter structure enhances the power of the bandage to cling on the limb for a longer period of time and be suitable for reuse. The bandage performance depends on the optimisation of these parameters to get desired efficacy of the compression system.     

Comparison of faecal culture and IS900 PCR assay for the detection of <Emphasis Type="Italic">Mycobacterium avium</Emphasis> subsp. <Emphasis Type="Italic">paratuberculosis</Emphasis> in bovine faecal samples

Comparative efficacy of faecal culture and IS900 Polymerase chain reaction (PCR) assay of faecal samples was investigated in 40 clinically suspected cases of Johne’s disease in dairy cattle. The sensitivity of faecal culture and PCR assay in this study was 52.5% (21/40) and 90% (36/40) respectively. All isolates appeared only on the mycobactin J supplemented Herrold’s egg yolk medium (HEYM) at 8–16 weeks post-inoculation, were acid-fast and were positive for IS900 PCR yielding a single amplicon of 217 bp. A total of 28 faecal samples out of 40 were positive by IS900 primary PCR assay for Mycobacterium avium subsp. paratuberculosis (Map) yielding an expected product of size 217 bp. Twelve faecal samples, which gave negative results in the primary PCR, were subjected to secondary PCR assay. Of the 12 samples, 8 gave positive results in the IS900 nested PCR (nPCR), which yielded a PCR product of 167 bp, proving better sensitivity of nPCR assay than single amplification PCR. PCR could detect additionally 15 samples as positive which were negative by faecal culture. The chi-square analysis showed a highly significant difference between the tests (P< 0.01). This study suggests that IS900-PCR-based detection of Map could be used as a potential diagnostic tool for rapid and effective Johne’s disease surveillance.     

Heterosis breeding in Indian mustard (Brassica juncea L. Czern & Coss): Analysis of component characters contributing to heterosis for yield

Summary Divergence of 25 accessions of Brassica juncea of Indian, CIS (Commonwealth of Independent States, former USSR) and synthetic origin was studied by D² analysis. On the basis of divergence, ten accessions were selected and crossed in a diallel fashion without reciprocals to study the combining ability and heterosis. None of the accessions was found to be a good general combiner for all the nine quantitative characters that were studied. Significant heterosis over better parent for single plant yield was recorded in CIS x Indian and synthetic x CIS crosses (5 each) followed by Indian x synthetic types (3). The analysis of component characters showed that the mean performance of the majority of hybrids was intermediate for five out of six yield attributing traits, thus exhibiting dominance or partial dominance effect. To estimate the contribution of such yield attributing traits towards heterosis for yield, a comparison was made among three parameters viz. heterosis over mid parent (MP), better parent (BP) and better yielding parent (BYP) of the concerned hybrid. It was observed that estimation of heterosis from BYP was a more accurate method to determine the contribution of component characters towards yield heterosis than the analysis based on MP and BP. From the component character analysis, it was concluded that characters like number of primary and secondary branches, number of siliqua per plant and siliqua density contributed significantly towards heterosis in yield. Plot level yield trials of two selected hybrids (Skorospieka II x RH30 and Donskaja IV x Varuna) over two growing seasons revealed 29.4 to 91.8% heterosis over BYP.     

Synthesis of somatic hybrids (RCBB) by fusing heat-tolerant Raphanus sativus (RR) and Brassica oleracea (CC) with Brassica nigra (BB)

Brassica carinata (BBCC), a potential oilseed crop for dry land agriculture, is sensitive to high temperatures during germination and early stages of growth, which thereby restricts the possibility of using the residual soil moisture available after the rainy season for its cultivation. To overcome this problem, a three‐genome hybrid, RCBB, was synthesized using Raphanus sativus (RR) and Brassica oleracea (CC) as donor sources for the desired heat tolerance. Protoplasts of RC hybrids obtained through sexual crosses between R. sativus (female) and B. oleracea (male) were fused with protoplasts of Brassica nigra (BB) to produce RCBB somatic hybrids. The hybrid colonies regenerated with an average frequency of 7.6%. Twelve out of 36 hybrids grown to maturity were characterized for their nuclear and organelle genomes. While all the hybrids showed the presence of B. nigra chloroplasts, 10 of the hybrids showed B. nigra‐specific mitochondria and two had Raphanus‐spedfic mitochondria. The somatic hybrids could be backcrossed to B. carinata.     

Standing biomass and carbon storage of above-ground structures in dominant mangrove trees in the Sundarbans

We evaluated carbon stocks in the above-ground biomass (AGB) of three dominant mangrove species (Sonneratia apetala, Avicennia alba and Excoecaria agallocha) in the Indian Sundarbans. We examined whether these carbon stocks vary with spatial locations (western region vs. central region) and with seasons (pre-monsoon, monsoon and post-monsoon). Among the three studied species, S. apetala showed the maximum above-ground carbon storage (t ha⁻¹) followed by A. alba (t ha⁻¹) and E. agallocha (t ha⁻¹). The above-ground biomass (AGB) varied significantly with spatial locations (p < 0.05) but not with seasons (p < 0.05). The variation may be attributed to different environmental conditions to which these areas are exposed to such as higher siltation and salinity in central region compared to western region. The relatively higher salinity in central region caused subsequent lowering of biomass and stored carbon of the selected species.     

A short duration of the Cretaceous-Tertiary boundary event: evidence from extraterrestrial helium-3

Analyses of marine carbonates through the interval 63.9 to 65.4 million years ago indicate a near-constant flux of extraterrestrial helium-3, a tracer of the accretion rate of interplanetary dust to Earth. This observation indicates that the bolide associated with the Cretaceous-Tertiary (K-T) extinction event was not accompanied by enhanced solar system dustiness and so could not have been a member of a comet shower. The use of helium-3 as a constant-flux proxy of sedimentation rate implies deposition of the K-T boundary clay in (10 +/- 2) x 10(3) years, precluding the possibility of a long hiatus at the boundary and requiring extremely rapid faunal turnover.     

UV/Methyl Ethyl Ketone Peroxide Mediated Chlorophenol Congener Degradation in Basic Media

The accumulation of Ag by the marine herbivorous gastropod, Littorina littorea, has been studied in a series of exposures in which the metal was added in aqueous form and as nanoparticles, both in the presence and absence of contaminated algal food (Ulva lactuca). Significant accumulation occurred in the gill, kidney, stomach and visceral mass when the snail was exposed to aqueous Ag in the absence of food. Despite the consumption of U. lactuca that had been previously contaminated by Ag, no accumulation was observed from the dietary route. When added as nanoparticles, accumulation of Ag was only measured in the head and gill and only in the absence of contaminated food. These observations suggest that Ag is most bioavailable to L. littorina when in true solution and that Ag measured in external tissues of the snail following exposure to nanoparticles arises from some physical association that does not result in significant transfer of the metal to internal organs.