Model legumes contribute to faba bean breeding

Faba bean is an excellent candidate crop to provide nitrogen input into temperate agricultural systems. However, its growth is hampered by several factors including environmental stresses and the presence of anti-nutritional factors. To solve these limitations, breeding programs have been initiated that were successful for monogenic traits but not so for multigenic traits. The large genome size of faba bean has slowed down breeding processes. Several other legumes have emerged as model legumes including Medicago truncatula, Lotus japonicus, Glycine max and Pisum sativum. The establishment of these models has already boosted our understanding of important processes such as the nitrogen-fixing symbiotic interaction. The high level of synteny and collinearity existing between legumes makes possible the transfer of key knowledge from model legumes to faba bean. Here we review the most recent knowledge gained from model legumes on grain quality, resistance to biotic and abiotic stresses, nitrogen-fixing symbiosis and how this knowledge can be employed for faba bean breeding.     

Copper,Zinc-Superoxide Dismutase Activity in Exercising Horses Fed Two Forms of Trace Mineral Supplements

Nine mature horses were used to evaluate superoxide dismutase (SOD) response to a low-intensity standard exercise test and the effect of copper (Cu) and zinc (Zn) supplement form on enzyme activity. The modified switchback experiment was conducted over seven 28-day periods. Horses were conditioned to perform an average daily workload of 3.93 kg∗km∗10⁻³ with a digestible energy (DE) demand of approximately 29 Mcal. Following a controlled Cu and Zn repletion-depletion diet sequence, horses were fed a diet intended to be marginally deficient in Cu and Zn with the minerals supplemented in either sulfate or organic chelate forms. Horses were then subjected to a standardized exercise test to enable evaluation of SOD activity during exercise and immediate recovery. In the final analyses, mineral contents of the experimental diets were significantly different (P < .05). The mean mineral concentration of the sulfate diet was 6.28 ppm Cu and 35.99 ppm Zn, while the chelate diet contained 23.62 ppm Cu and 90.67 ppm Zn. Even so, resting SOD activity was not altered by diet (1793.47 ± 323.00 U/g Hb for the sulfate diet, 1355.70 ± 148.32 U/g Hb for the organic-chelate diet), nor did SOD activity change in response to the low-intensity workout. The SOD activity was unchanged by feeding a Cu and Zn supplemented diet to horses fed to be in a mineral-deficient state. These exercise bouts did not appear to have a significant impact on SOD activity. Other types of oxidative stress should be considered when trying to evaluate the antioxidant responsiveness of this enzyme.     

Has global environmental change caused monsoon rainforests to expand in the Australian monsoon tropics?

A large research program in the Australian monsoon tropics has concluded that monsoon rainforests have expanded within the savanna matrix, a trend that has been emulated throughout the tropics worldwide. The driver of the northern Australian trend was not resolved, but it was suggested to be linked to a long-term trend towards wetter climates, atmospheric CO₂ enrichment, and changed fire regimes. We review these findings with particular consideration of its analytical and evidentiary basis and plausibility of the global change hypothesis. Field validation has largely demonstrated that the aerial photographic technique that underpinned the previous research is reliable enough to detect rainforest expansion. Statistical modelling demonstrated that the expansion is related to sites with regionally low fire activity, although models are of low explanatory power reflecting the sketchy historical records of fire and feral animal impacts. Field studies show that current fire regimes adjacent to expanding rainforest patches are causing populations of the native conifer Callitris intratropica, an obligate seeder, to crash. Therefore, it is unlikely that changes in fire regimes, which have been deleterious to other fire-sensitive taxa and plant communities in the region, are responsible for the rainforest expansion. We conclude that the expansion of monsoon rainforests is most plausibly linked to the current wetting trend or elevated CO₂ concentration. Increases in either water availability or CO₂ concentration can potentially overwhelm the negative feedback between fire and rainforest cover that is responsible for the meta-stability of monsoon rainforest boundaries. However, further research at the continental scale, using aerial photography, tree rings and other proxies, is required to evaluate this hypothesis.     

Polarized epithelium-sperm co-culture system reveals stimulatory factors for the secretion of mouse epididymal quiescin sulfhydryl oxidase 1

Spermatozoa acquire fertilization ability through post-translational modifications. These membrane surface alterations occur in various segments of the epididymis. Quiescin sulfhydryl oxidases, which catalyze thiol-oxidation reactions, are involved in disulfide bond formation, which is essential for sperm maturation, upon transition and migration in the epididymis. Using castration and azoospermia transgenic mouse models, in the present study, we showed that quiescin sulfhydryl oxidase 1 (QSOX1) protein expression and secretion are positively correlated with the presence of testosterone and sperm cells. A two-dimensional in vitro epithelium-sperm co-culture system provided further evidence in support of the notion that both testosterone and its dominant metabolite, 5α-dihydrotestosterone, promote epididymal QSOX1 secretion. We also demonstrated that immature caput spermatozoa, but not mature cauda sperm cells, exhibited great potential to stimulate QSOX1 secretion in vitro, suggesting that sperm maturation is a key regulatory factor for mouse epididymal QSOX1 secretion. Proteomic analysis identified 582 secretory proteins from the co-culture supernatant, of which 258 were sperm-specific and 154 were of epididymal epithelium-origin. Gene Ontology analysis indicated that these secreted proteins exhibit functions known to facilitate sperm membrane organization, cellular activity, and sperm-egg recognition. Taken together, our data demonstrated that testosterone and sperm maturation status are key regulators of mouse epididymal QSOX1 protein expression and secretion.     

A short, reliable, highly reproducible complement fixation test for the serological diagnosis of contagious equine metritis

A complement fixation test, using round-bottomed microtitration plates and an 8 channel microdiluter, based on that used for brucellosis by Herr, Huchzermeyer, Te Brugge, Williamson, Roos & Schiele, 1985, has been developed for use on the sera of horses to detect antibodies to the contagious equine metritis organism. The results with 2 known positive sera tested 116 times in 27 separate tests were reproducible for the most part within a twofold range. They seldom exceeded these limits and never exceeded a fourfold range. The test itself is capable of being carried out within 90 min. The test was slightly more sensitive when sera were inactivated in a hot air oven for 50 min at 58 degrees C, as compared to inactivation at 62 degrees C in a water-bath for 50 min. There were no false negative or false positive reactions and no anticomplementary activity in the sera tested.