In vitro micro propagation of “sand pear” Pyrus pyrifolia (Burm. f.) Nakai

This study was undertaken to standardize protocols for in vitro explant establishment, shoot multiplication and in vitro rooting for Pyrus pyrifolia, growing in the Kashmir valley. The explant used was nodal cuttings of 2–3cm size with one or two axillary buds. The highest explant establishment (over 90%) was observed during spring while the lowest (60%) explant establishment frequency was observed during winter season. The shoots sprouted from the axillary buds were excised and subcultured on MS basal medium. The highest shoot multiplication rate (130 shoots from a single nodal cutting) was obtained on MS medium supplemented with BAP 2.2 mg·L^?1 and kinetin 1 mg·L^?1 after four weeks. The shoots were inoculated for rooting in root induction medium of half strength MS salts supplemented with plant growth regulators like IBA, IAA, NAA, and 2, 4-D. However, the best rooting response (8.50 roots per shoot) was obtained in combination of hormones (IBA + NAA) 0.25 mg·L^?1 each. The rooted micro shoots were acclimatized under decreasing humidity regime (95% RH to 75% RH over a period of 5±1 weeks). The highest ex vitro plantlet survival percentage (56.50%) of Pyrus pyrifolia was observed on sand + soil (1:1 v/v).     

Immune responses against Marek's disease virus

It is more than a century since Marek's disease (MD) was first reported in chickens and since then there have been concerted efforts to better understand this disease, its causative agent and various approaches for control of this disease. Recently, there have been several outbreaks of the disease in various regions, due to the evolving nature of MD virus (MDV), which necessitates the implementation of improved prophylactic approaches. It is therefore essential to better understand the interactions between chickens and the virus. The chicken immune system is directly involved in controlling the entry and the spread of the virus. It employs two distinct but interrelated mechanisms to tackle viral invasion. Innate defense mechanisms comprise secretion of soluble factors as well as cells such as macrophages and natural killer cells as the first line of defense. These innate responses provide the adaptive arm of the immune system including antibody- and cell-mediated immune responses to be tailored more specifically against MDV. In addition to the immune system, genetic and epigenetic mechanisms contribute to the outcome of MDV infection in chickens. This review discusses our current understanding of immune responses elicited against MDV and genetic factors that contribute to the nature of the response.     

Cottonseed with a high (+)- to (-)-gossypol enantiomer ratio favorable to broiler production

This study was designed to evaluate the relative toxicity of (+)- and (-)-gossypol enantiomers in 0-3-week-old broilers. Treatments consisted of broiler starter diets formulated with either a glandless, which did not contain gossypol, a commercial glanded [62. 2% (+)-gossypol], or a glanded moco [83.2% (+)-gossypol] crushed cottonseed (CCS) (six replicates/treatment) plus a soybean meal negative control. Glandless cottonseed was mixed with the moco cottonseed (2.4% free gossypol) so that both the commercial glanded and moco glanded cottonseeds contained equivalent concentrations of free gossypol (2.0%). The cottonseed treatments were added at 5 and 10% of the diet. Body weights and feed conversions were determined weekly. Body weights and feed-to-gain ratios of broilers fed 5 and 10% glandless CCS and 5% moco CCS were not significantly different. Broilers receiving 10% commercial glanded CCS weighed significantly less than those subjected to all other treatments. Feed-to-gain ratios were significantly higher for broilers receiving 10% commercial glanded and 10% moco CCS as compared to 5% moco and glandless CCS, 10% glandless CCS, and control. Relative liver weights of birds receiving 10% moco CCS were significantly less than those of birds receiving 10% commercial CCS. The data clearly showed that broilers fed moco CCS containing a relatively high (+)- to (-)-gossypol enantiomer ratio performed better than broilers receiving commercial CCS with a lower (+)- to (-)-gossypol enantiomer ratio.     

The Xanthomonas oryzae pv. oryzae type IV pilus alignment subcomplex protein PilN contributes to regulation of bacterial surface-associated behaviours and T3SS system

The gram-negative plant pathogen Xanthomonas oryzae pv. oryzae (Xoo) is able to infect the host rice and effectively colonize in vascular tissues. The type IV pilus (T4P) is one of the major virulence factors playing an important role in migration of Xoo through host vascular tissues. Here, we identified PilN, a T4P alignment subcomplex protein, which is involved in regulation of swimming motility, and analysed its contribution to bacterial surface-associated behaviours and virulence. We found that the pilN deletion mutant exhibited dramatically reduced twitching motility and scarcely detectable levels of T4P major pili PilA, as well as enhanced biofilm formation and exopolysaccharide (EPS) production. In addition, deletion of the pilN gene in Xoo resulted in impaired virulence in host rice and attenuated type III secretion system (T3SS) genes expression, which is independent of PilA assembly. Expression of the relevant pilN gene in trans was capable of restoring twitching motility and biofilm formation to the wild-type levels in the pilN mutant but partially recovering EPS production and virulence. Moreover, the expression of trh and xrvA genes, which encode the HrpG positive regulators, was decreased in the pilN mutant. Our results suggest that PilN executes versatile functions in bacterial virulence and cell surface-associated behaviours.     

Validation of molecular markers for resistance among Pakistani chickpea germplasm to races of <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f. sp. <Emphasis Type="Italic">ciceris</Emphasis>

DNA markers in chickpea, targetting resistance genes for different races of Fusarium oxysporum f.sp. ciceris (Foc), have been identified in chickpea, but validation of these markers is essential for effective use in resistance breeding. In view of this, different simple sequence repeats (SSR) markers were analysed in Pakistani germplasm including induced mutants and some local lines. Most of the SSR markers showed good correlation with phenotypic evaluation of genotypes to different races of Foc and may be used effectively in resistance breeding, except those markers for race 3. Markers for race 3 showed deviations from phenotypic data and the reason might be that race 3 is actually Fusarium proliferatum as reported recently and resistance to this race might involve some other major resistance genes. Poor correlation of markers with foc-3 on LG2 in our study and a recent report of independent segregation of foc-2 and foc-3 in near isogenic lines suggested that linkage distances among different resistance genes need further investigation. Moreover three Pakistani mutant lines (97477, CM444/92 and CM368/93) depicted high levels of resistance to Foc races and can be deployed as a valuable source in resistance breeding programmes.     

The influence of 12 years of tillage and crop rotation on total and labile organic carbon in a sandy loam soil

Information on which management practices can enhance soil organic matter (SOM) content and quality can be useful for developing sustainable crop production systems. We tested the influence of 12 years of no-till (NT) versus conventional tillage (CT), and four crop sequences on the organic C pools of a Grey Luvisolic sandy loam soil in northwestern Alberta, Canada. The crop sequences were: continuous wheat (Triticum aestivum L.), field pea (Pisum sativum L.)–wheat–canola (Brassica rapa L.)–wheat, red clover (Trifolium pratense L.) green manure–wheat–canola–wheat/red clover and fallow–wheat–canola–wheat. Soil samples from 1992, when the study was initiated, and 1996, 2000 and 2004 were analyzed for total organic C (TOC), the light fraction (LF) and its C content, and water-soluble and mineralizable C. Total organic C in the top 15 cm of soil was higher in the red clover rotation than either the pea or fallow rotation by 1996. The tillage effect became significant only in 2004 with NT having a higher TOC than CT. The LF dry matter (DM) increased from 6.9 g kg⁻¹ soil in 1992 to a range of 10–13 g kg⁻¹ in 2000 and 2004. It was higher under NT than CT in 2 of 3 years and in the red clover rotation than the pea or fallow rotation in 1 of 3 years. The LF C content exhibited a similar trend as LF DM. The water-soluble and mineralizable C pools were not affected by tillage but decreased with time. Among crop rotations, the red clover rotation tended to result in higher levels of hot water-soluble and mineralizable C. It is concluded that tillage had a greater influence than crop rotation on the LF DM and LF C (as indicators of C storage), whereas the converse effect applied to mineralizable C and, to a lesser degree, hot water-soluble C (as indicators of SOM quality).     

The potential of precision surface irrigation in the Indus Basin Irrigation System

In this research we explore the potential of precision surface irrigation to improve irrigation performance under the warabandi system prevalent in the Indus Basin Irrigation System. Data on field dimensions, field slopes along with characteristic soil infiltration properties and outlet discharge were collected through a survey of a sample tertiary unit of Maira Branch Canal, Khyber Pakhtunkhwa Province, Pakistan. The performance of all fields in the tertiary unit was analysed and reported in aggregate, with detailed results of one field presented for illustration. The objective is to determine the optimum field layout, defined as the number of border strips, for the observed field characteristics to maximize performance. The results indicate that performance improvement is relatively easily achievable through changes in field layout within current irrigation services. Estimated application efficiency is sensitive to the selected depth of application, and it is important that a practical depth of application is selected. We recommend a depth of application of 50 mm and show how this is achievable and leads to a low quarter distribution uniformity of 0.750 and an application efficiency of 80 %. We also explore the feasibility of a 10-day warabandi rather than the 7-day warabandi and show that there is no significant change in the performance under a 10-day warabandi.     

Origin of whales from early artiodactyls: hands and feet of Eocene Protocetidae from Pakistan

Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis, are among the oldest known protocetid archaeocetes. These came from early Lutetian age (47 million years ago) strata in eastern Balochistan Province, Pakistan. Both have an astragalus and cuboid in the ankle with characteristics diagnostic of artiodactyls; R. balochistanensis has virtually complete fore- and hind limbs. The new skeletons are important in augmenting the diversity of early Protocetidae, clarifying that Cetacea evolved from early Artiodactyla rather than Mesonychia and showing how early protocetids swam.     

A chronology of Paleozoic sea-level changes

Sea levels have been determined for most of the Paleozoic Era (542 to 251 million years ago), but an integrated history of sea levels has remained unrealized. We reconstructed a history of sea-level fluctuations for the entire Paleozoic by using stratigraphic sections from pericratonic and cratonic basins. Evaluation of the timing and amplitude of individual sea-level events reveals that the magnitude of change is the most problematic to estimate accurately. The long-term sea level shows a gradual rise through the Cambrian, reaching a zenith in the Late Ordovician, then a short-lived but prominent withdrawal in response to Hirnantian glaciation. Subsequent but decreasingly substantial eustatic highs occurred in the mid-Silurian, near the Middle/Late Devonian boundary, and in the latest Carboniferous. Eustatic lows are recorded in the early Devonian, near the Mississippian/Pennsylvanian boundary, and in the Late Permian. One hundred and seventy-two eustatic events are documented for the Paleozoic, varying in magnitude from a few tens of meters to approximately 125 meters.