Influence of photoperiod on the frequency of sexual embryo saes in facultative apomictic buffelgrass

Summary The frequency at which sexual embryo sacs occur in some facultatively apomictic species is influenced by photoperiod. This research was conducted to study changes in the frequency of sexual embryo sacs (SES) in field-grown accessions of buffelgrass [Pennisetum ciliare (L.) Link] and to determine the influence of photoperiod on the expression of sexuality under controlled environmental conditions. In a 3-yr field study, mean frequency of SES collected from two facultative buffelgrass accessions (PI 409266 and 409277) ranged from 2.5 to 8.6 percent. Within each year, the greatest number of SES were observed during spring and summer, while a reduction in SES occurred during the late summer and early fall. Under controlled environmental conditions equal numbers of SES were observed from plants grown at 8, 12, and 16 h. For the two facultative accessions of buffelgrass examined in this study, it was concluded that no relationship existed between photoperiod and frequency of SES under either field or controlled environmental conditions.     

The use of neutron tomography for the structural analysis of corn kernels

Neutron tomography was studied as a technique for non-destructively analyzing the internal structure of dried corn kernels. The study had two goals: first, to determine if the analysis could identify well-known anatomical features of the kernels; and second, to determine if it could distinguish between different types and treatments of kernels. Specifically, kernels which were infected vs. uninfected with the aflatoxin-producing fungus Aspergillus flavus were analyzed. Two different varieties of corn were used: VA35 (susceptible to A. flavus infection) and GT-MAS:gk (resistant). It was found that many anatomical features of the kernels could be identified using neutron tomography, including the scutellum, endosperm, aleurone, pericarp, pedicel, coleorhizae, radical, plumule, and coleoptile. Furthermore, differences were detected between susceptible kernels that had been inoculated and those that had not. Infected kernels were found to have lower neutron attenuation in the scutellum and embryo regions, possibly caused by lower hydrogen concentrations due to fungal degradation. No systematic structural differences were detected between resistant inoculated and resistant uninoculated kernels, as expected. This study indicated that neutron tomography could be a useful technique for the structural analysis of corn, and possibly other grains or small biological objects.     

The Effect of Glasshouse Red Spider Mite (Tetranychus Urticae Koch) on the Yield of Cucumbers

The effect on yield of cucumbers of different degrees of damage caused by different levels of mite populations was determined. Yield was unaffected until the foliar damage rose above a level which corresponds to about 30% of the total leaf area. It is shown that when a spraying programme reduced the leaf injury below this level the crop would be unaffected, and that between four and eight sprays per season would be adequate to do this instead of the present average of twelve. Decrease in the frequency of chemical applications should slow down the development of populations resistant to specific materials.     

Effects of parturition and dexamethasone on DNA methylation patterns of IFN-γ and IL-4 promoters in CD4+ T-lymphocytes of Holstein dairy cows

This study investigated epigenetic mechanisms by which DNA methylation affects the function of bovine adaptive immune system cells, particularly during the peripartum period, when shifts in type 1 and type 2 immune response (IR) biases are thought to occur. Stimulation of CD4+ T-lymphocytes isolated from 5 Holstein dairy cows before and after parturition with concanavalin A (ConA) and stimulation of CD4+ T-lymphocytes isolated from 3 Holstein dairy cows in mid-lactation with ConA alone or ConA plus dexamethasone (Dex) had significant effects on production of the cytokines interferon gamma (IFN-γ, type 1) and interleukin 4 (IL-4, type 2) that were consistent with DNA methylation profiles of the IFN-γ gene promoter region but not consistent for the IL-4 promoter region. ConA stimulation increased the production of both cytokines before and after parturition. It decreased DNA methylation in the IFN-γ promoter region but increased for IL-4 promoter region. Parturition was associated with an increase in IFN-γ production in ConA-stimulated cells that approached significance. Overall, DNA methylation in both promoter regions increased between the prepartum and postpartum periods, although this did not correlate with secreted cytokine concentrations. Dexamethasone treated cells acted in a manner consistent with the glucocorticoid’s immunosuppressive activity, which mimicked the change at the IFN-γ promoter region observed during parturition. These results support pregnancy as type 2 IR biased, with increases of IFN-γ occurring after parturition and an increase in IL-4 production before calving. It is likely that these changes may be epigenetically controlled.     

Salmonella monitoring programs in Australian feed mills: a retrospective analysis

The availability of safe, commercially prepared stock feed for production animals is an important step in ensuring animal health and welfare and the safety of food animal products for human consumption. Animal feed quality assurance programs include microbiological monitoring of raw materials, mill equipment and finished feed. Over a period of 16 years, 23,963 samples for Salmonella culture and serotyping were collected from 22 stock feed mills. A multivariable generalized linear mixed model (GLMM) was used to identify mill and sample type factors that increase the odds of detecting Salmonella. The odds of detecting a Salmonella positive sample was greatest in samples from raw materials and in mills that processed restricted animal material (RAM). The percentage of positive samples ranged from 7.2% in 2003 to 2.8% in 2017. Of the 1,069 positive samples, 976 were serotyped with 61 different Salmonella serotypes isolated. The serotype most frequently isolated from raw materials was S. Agona, (n = 108) whilst S. Anatum was the serotype most frequently isolated from equipment and finished feed (n = 156). The diversity of Salmonella serotypes differed between mills and different stages of the production line. Microbiological monitoring in the commercial preparation of animal feed in Australian stock feed mills guides the implementation of quality control measures and risk mitigation strategies thereby reducing the prevalence and diversity of potentially zoonotic bacteria such as Salmonella, enhancing food safety for both animal and consumer.