A cross disciplinary framework for linking farms with regional groundwater and salinity management targets

Irrigation delivers major benefits in food security and human development. Irrigation also leads to waterlogging and salinity which threaten the sustainability of irrigated agriculture and pose major socioeconomic and environmental risks. The issue can be addressed by limiting net recharge to groundwater such that the water and salt keep natural equilibria. Often the information on net recharge within catchments is unavailable, particularly at lower spatial scales such as the farm or paddock; this offers little guidance for on-farm land and water management decisions—basic decisions that ultimately impact regional net recharge and waterlogging and salinity dynamics. This paper develops a cross disciplinary framework based on the concept of net recharge for setting paddock scale targets and to link these to the regional targets and community's goals for sustainable irrigation management. A management model, cast in a dynamic programming format to integrate a detailed hydrological model with an economic model was applied to estimate the productivity, profitability and sustainability of irrigated agriculture in a region of the Murray Darling Basin in Australia. SWAGMAN^® Farm model was used to determine paddock scale net recharge. This interactive model enables an individual farmer to choose a profit optimizing crop mix while lowering net recharge; this in turn leads to a win-win outcome for all farmers. The net recharge metric can be used for the conversion of diffuse source groundwater recharge to a point source recharge at paddock scale, enabling the definition of private property rights to a common pool problem and assigning individual responsibilities for its management—a vexing issue and a new concept for the commons literature. Net recharge shows significant spatial and temporal variation which warrants a targeted/zonal approach to address the issue. Regional and targeted strategies and actions to address the issue are identified. Apart from its applied and action research orientation, the development of paddock scale net recharge metric is perhaps the most significant conceptual contribution of this research which can lead to shared management of groundwater aquifers.     

Cardiolipin polyspecific autoreactivity in two broadly neutralizing HIV-1 antibodies

The design of a human immunodeficiency virus-1 (HIV-1) immunogen that can induce broadly reactive neutralizing antibodies is a major goal of HIV-1 vaccine development. Although rare human monoclonal antibodies (mAbs) exist that broadly neutralize HIV-1, HIV-1 envelope immunogens do not induce these antibody specificities. Here we demonstrate that the two most broadly reactive HIV-1 envelope gp41 human mAbs, 2F5 and 4E10, are polyspecific autoantibodies reactive with the phospholipid cardiolipin. Thus, current HIV-1 vaccines may not induce these types of antibodies because of autoantigen mimicry of the conserved membrane-proximal epitopes of the virus. These results may have important implications for generating effective neutralizing antibody responses by using HIV-1 vaccines.     

Crop diversity and pest management in sustainable agriculture

Large-scale crop monocultures facilitate the proliferation and increasing prevalence of diseases and pest insects. Many studies highlight the impacts of plant diversification upon pathogens, and the population dynamics of insects and beneficial organism in agricultural ecosystems. These studies provide evidence that habitat manipulation techniques such as intercropping, relay, and rotation can significantly improve disease and pest management. This review introduces the concept of crop diversity, considers recent insights and mechanisms underlying crop diversity, and discusses its potential for improving sustainable agricultural practices. Recently, the phytobiomes resulting from increased crop diversity are increasingly recognized for their contribution to disease and pest control. Further, understanding the interactions between pathogens or pests with their host phytobiome may lead to novel options for the prevention of pests. Recent advances in the agricultural systems include:(i) a better understanding of the mechanisms of interactions between crop species and genotypes;(ii) ecological progress including a better understanding of the context-dependency of those interactions; and(iii) the role of microtopographic variation in agricultural systems for priming basal resistance to multiple pests and pathogens by intercropped crops. We also highlight recent progress in China and the potential options for habitat management and design that enhance the ecological role of biodiversity in agroecosystems.     

Passage of heme-iron across the envelope of Staphylococcus aureus

The cell wall envelope of Gram-positive pathogens functions as a scaffold for the attachment of virulence factors and as a sieve that prevents diffusion of molecules. Here the isd genes (iron-regulated surface determinant) of Staphylococcus aureus were found to encode factors responsible for hemoglobin binding and passage of heme-iron to the cytoplasm, where it acts as an essential nutrient. Heme-iron passage required two sortases that tether Isd proteins to unique locations within the cell wall. Thus, Isd appears to act as an import apparatus that uses cell wall-anchored proteins to relay heme-iron across the bacterial envelope.     

Isolation of pathogenic aerobic bacteria from the blood of septicaemic neonatal calves and the susceptibility of isolates to various antibiotics

An automated blood culture system (BACTEC 9240) was used for the isolation of aerobic bacteria from the blood of septicaemic neonatal calves. Blood samples were collected from 90 clinically septicaemic and 20 healthy neonatal calves and inoculated into blood culture bottles. There were 89 significant isolates from 90 positive blood cultures using the BACTEC system. Escherichia coli was the most common pathogen detected accounting for 56 (63%) out of 89 isolates. The other pathogens were beta-haemolytic streptococci (15.7%), Staphylococcus aureus (10.1%), Klebsiella sp. (5.6%) and Corynebacterium sp. (5.6%). All isolates showed a susceptibility rate of 100% to enrofloxacin, cefepim, cefoperazone/sulbactam, imipenem and meropenem while some of them were ranged from 75 to 91.7% susceptible to amoxicillin/clavulanic acid, ampicillin/sulbactam, gentamicin and cephalosporins.     

Mapping of quantitative trait loci controlling cotton leaf curl disease resistance in upland cotton

Cotton leaf curl disease (CLCuD) is a major threat to cotton production in Asia and Africa. Using marker-assisted breeding can be the best sustainable approach to tackle CLCuD. Identification of new QTLs in the indigenous cotton germplasm is necessary to combat CLCuD. The current study was designed to construct a genetic linkage map of bi-parental F2:F3 populations developed from highly tolerant MNH-886 and highly susceptible S-12 cotton cultivars. One hundred seven CLCuD-associated simple sequence repeat (SSR) marker alleles were identified as polymorphic and three new QTLs were found on chromosomes C11, C19 and C21. Two QTLs on chromosomes C11 and C19 were detected in both F2 and F3 populations in the region flanked by SSR markers CIR316 and BNL4094, and BNL285 and BNL3348, respectively. Whereas, one QTL on chromosome C21 was detected in the region flanked by SSR markers JESPR158 and JESPR135 in both F2 and F3 generations. The CLCuD-associated QTLs identified in this study can help fine-tune the molecular mapping of the QTLs on the cotton genome against CLCuD.     

A single subtype of avian pneumovirus circulates among Minnesota turkey flocks.

The recent emergence of avian pneumovirus (APV) infection among US turkey flocks has resulted in a major economic threat to the turkey industry. In order to elucidate the molecular epidemiology of APV, comparative sequence analysis of the fusion (F) protein gene of APV was performed for 3 cell culture-adapted isolates and 10 APV positive clinical samples recovered from US turkey flocks. Relatively modest levels of nucleotide and amino acid sequence divergence were identified, suggesting the prevalence of a single lineage of APV among US turkey flocks. Additionally, numerous polymorphisms were identified that were only represented in the clinical samples but not in the in vitro propagated isolates of APV. Phylogenetic analyses confirm that the subtype of APV circulating in the upper Midwestern United States is evolutionarily related to, but distinct from, European APV subgroups A and B. Overall, the results of the present investigation suggest that there has been only a single recent introduction of APV into US turkey populations in the upper Midwestern United States.     

Analysing the effect of dietary prebiotics and probiotics on gut bacterial richness and diversity of Asian snakehead fingerlings using T‐RFLP method

This study was designed to evaluate the effects of three prebiotics (β‐glucan, galacto‐oligosaccharide [GOS], mannan‐oligosaccharide [MOS]) and two probiotics (Saccharomyces cerevisiae, Lactobacillus acidophilus) on the microbiome of snakehead during growth of fingerlings. In addition, the experiment evaluated the capacity of Channa striata fingerlings to retain the benefits derived from these supplements after withdrawal. Throughout the study, it was observed that supplementation with dietary prebiotics and probiotics led to significant (p < 0.05) change in gut bacterial profile and improvement in gut morphology. Terminal restriction fragment length polymorphism (T‐RFLP) was used for the comparative analysis of gut communities and all 46 of the T‐RFLP detected phylotypes were present in the Lactobacillus supplemented fish, while significantly fewer were detected in controls and other experimental supplement regimes. Histological studies and electron microscopy revealed that both the prebiotic and probiotic treated fish had significantly longer and wider villi and deeper crypts compared to the controls. The microvilli length, as evaluated with electron microscopy, was also longer in all treated fish compared to controls. Furthermore, this study is the first to report the absence of differences in sustaining the efficacies attained after intake of β‐glucan, GOS, MOS and live yeast upon post‐feeding with an unsupplemented feed, over a prolonged period.     

A Study of Airborne Selected Metals and Particle Size Distribution in Relation to Climatic Variables and their Source Identification

Ten selected metals (Na, K, Fe, Zn, Pb, Mn, Cr, Co, Ni & Cd) were estimated in total suspended particulate (TSP) samples collected on glass fibre filters in urban Islamabad, Pakistan, from October 2002 to May 2003, using a high volume sampling technique. The wet digestion method (HNO₃/HClO₄) was used for metal analysis by the flame atomic absorption spectrophotometry (FAAS) method. Maximum mean contribution was noted for Na (1.949 μg m^?3), followed by K (0.900 μg m^?3), Zn (0.603 μg m^?3), Fe (0.584 μg m^?3) and Pb (0.214 μg m^?3). The particle size determination on % volume basis for four fractions (PM_{< 2.5}, PM_2.5–10, PM_10–100& PM_{> 100}) was also carried out. PM_10–100 were found to be the most abundant in the local atmosphere followed by PM_2.5–10, while the respirable fraction (PM_{< 2.5}) and giant fraction (PM_{> 100}) showed comparable and lower levels. The trace metals were found to be mainly associated with PM_{< 2.5} and PM_2.5–10. The influence of climatic variables on toxic trace metals and particle size fractions was also investigated statistically and it was revealed that temperature has a significant correlation with fine particle fractions and airborne trace metal levels. The source identification was carried out by Principal Component Analysis and Cluster Analysis. Four metal sources were identified: industrial (32.6%), soil-derived dust (21.9%), traffic/road dust (19.8%), and metallurgical/garbage incineration (12.4%). The metal levels were also compared with those reported for other parts around the world.