No abstract

Three EST-derived microsatellite loci from Vitis vinifera were amplified and sequenced across eight species of Vitaceae from four different genera. Phylogenetic analysis of the microsatellite's flanking regions produced informative results in congruence with previous studies. Generic relationships were respected and the data produced sufficient inter-specific variation to distinguish between Cayratia acris and Cayratia saponaria, two very closely related species. Overall, the sequence alignments showed that priming sites were conserved, whereas microsatellite repeats were present in most cases but structurally variable. The sequence data provided information on the evolutionary patterns of various microsatellite repeats and their correlation to evolutionary relationships among taxa.

Ruminants obtain nutrients from microbial fermentation of plant material, primarily in their rumen, a multilayered forestomach. How the different layers of the rumen wall respond to diet and influence microbial fermentation, and how these process are regulated, is not well understood. Gene expression correlation networks were constructed from full thickness rumen wall transcriptomes of 24 sheep fed two different amounts and qualities of a forage and measured for methane production. The network contained two major negatively correlated gene sub-networks predominantly representing the epithelial and muscle layers of the rumen wall. Within the epithelium sub-network gene clusters representing lipid/oxo-acid metabolism, general metabolism and proliferating and differentiating cells were identified. The expression of cell cycle and metabolic genes was positively correlated with dry matter intake, ruminal short chain fatty acid concentrations and methane production. A weak correlation between lipid/oxo-acid metabolism genes and methane yield was observed. Feed consumption level explained the majority of gene expression variation, particularly for the cell cycle genes. Many known stratified epithelium transcription factors had significantly enriched targets in the epithelial gene clusters. The expression patterns of the transcription factors and their targets in proliferating and differentiating skin is mirrored in the rumen, suggesting conservation of regulatory systems.

The use of microsatellite loci developed from a single plant species across a number of related taxa is becoming increasingly widespread. This approach can provide highly informative markers even for species for which microsatellites have not been characterized. As a number of expressed sequence tag (EST)-derived and enrichment-derived microsatellites are available for grape (Vitis vinifera), this study set out to assess transferability of nine such loci across 25 species from five different Vitaceae genera. Intergeneric transfer success in Vitaceae was high (51.1%) and EST-derived loci performed better than enrichment-derived loci. Six loci were further tested across two Australian native species, Cissus hypoglauca and C. sterculiifolia, in order to assess the conservation of microsatellite repeats and their flanking sequences. Polymorphism of these selected loci was successfully tested for each species across a small, isolated rain forest population from northern New South Wales (Australia). Results from this preliminary investigation suggest that it is possible to use grape-derived simple sequence repeats (SSR) loci for population studies on Vitaceae. As Vitaceae are an important component of rain forest flora, the availability of such highly informative loci will be beneficial to future studies aimed at determining the genetic consequences of rain forest fragmentation.

Practical and reliable measurement of pasture intake by individual animals will enable improved precision in livestock and pasture management, provide input data for prediction and simulation models, and allow animals to be ranked on grazing efficiency for genetic improvement. In this study, we assessed whether pasture intake of individual grazing cattle could be estimated from time spent exhibiting behaviours as determined from data generated by on-animal sensor devices. Variation in pasture intake was created by providing Angus steers (n = 10, mean ± s.d. liveweight 650 ± 77 kg) with differing amounts of concentrate supplementation during grazing within individual ryegrass plots (≤0.22 ha). Pasture dry matter intake (DMI) for the steers was estimated from the slope (kg DM day–1) of the regression of total pasture DM per plot on intake over an 11-day period. Pasture DM in each plot, commencing with ≤2 t DM ha–1, was determined by using repeatedly calibrated pasture height and electronic rising plate meters. The amounts of time spent grazing, ruminating, walking and resting were determined for the 10 steers by using data from collar-mounted, inertial measurement units and a previously developed, highly accurate, behaviour classification model. An initial pasture intake algorithm was established for time spent grazing: pasture DMI (kg day–1) = –4.13 + 2.325 × hours spent grazing (P = 0.010, r2 = 0.53, RSD = 1.65 kg DM day–1). Intake algorithms require further development, validation and refinement under varying pasture conditions by using sensor devices to determine specific pasture intake behaviours coupled with established methods for measuring pasture characteristics and grazing intake and selectivity.