Vaginal smear cycle in 4-day cyclic Chinese hamsters, Cricetulus griseus]

The contents of vaginal smear of 4-day cyclic Chinese hamster (Cricetulus griseus) was investigated every 3 hours for 5 days. A light-dark cycle of 14--10 hr was used with the lights turned on at 6 : 00 a.m. Estrous cycle of the Chinese hamster determined by vaginal smears can be divided into 6 periods. The proestrous phase started at about 0 : 00 of day 1, the day of the proestrous phase was designated as day 1 of the estrous cycle. In the afternoon of the same day 1, nucleated epithelial cells gradually increased in number (proestrus : I), and the vaginal contents became to consist solely of nucleated epithelial cells at about 18 : 00 to 21 : 00 (estrus : II). At about 0 : 00 of day 2, however, nucleated epithelial cells were superseded suddenly by cornified epithelial cells, and this phase lasted for 9 to 12 hr (metestrus I : III). Towards the end of the cornified stage, nucleated cells appeared in short duration (metestrus II : IV). And then, in the evening of day 2, leucocytes gradually increased in number with degeneration of nucleated cells (diestrus I : V-1). On day 3, vaginal smear contained a large amount of mucus as well as degenerated nucleated cells and leucocytes (diestrus II : V-2). At about 21 : 000 of day 4, some cornified epithelial cells were seen and then proestrous stage was returned. The females were mated with 3 to 5 males in the evening of day 1, copulation was confirmed in 83.7% females in the next morning,thus the copulation in the Chinese hamster may be thought to occur during the vaginal smear stage of nucleated epithelial cells (estrous phase), i.e. about 18 : 00 to 24 : 00 of day 1.     

Possible involvement of momilactone B in rice allelopathy

Since residues and extracts of rice plants were known to inhibit the germination and growth of several plant species, the possible involvement of a growth inhibitor, momilactone B, in rice allelopathy was discussed. Momilactone B was found in shoots and roots of rice plants over their entire life cycle. The level of momilactone B in shoots and roots increased with rice plant growing until flowering initiation, and then decreased. The highest level of momilactone B in the shoots and roots at the day of flowering initiation was 245 and 64.1 nmol g(-1) fresh weight, respectively. Thus, 1 kg of rice shoots and roots, respectively, may be able to release 245 and 64.1 micromol of momilactone B into the soil or neighboring environment by decomposition of their residues, which may be sufficient to cause growth inhibition of their neighboring or successional plants. The growth inhibitory activity of momilactone B and the occurrence of momilactone B in rice plants suggest that momilactone B may contribute the growth inhibitory effect of rice residues and extracts, indicating that momilactone B may have an important role in the rice allelopathy.     

Concentration and release level of momilactone B in the seedlings of eight rice cultivars

The release levels of a growth inhibitor, momilactone B, from rice (Oryza sativa L.) seedlings of eight cultivars were compared with the endogenous concentrations of momilactone B in their seedlings. All rice cultivars contained momilactone B in the seedlings, and their concentrations differed between the cultivars. Momilactone B was also found in all culture solutions in which these rice seedlings were grown, and the concentrations differed between the cultivars. The momilactone B concentrations in the culture solutions were reflected in the momilactone B concentrations in the seedlings. These results suggest that all rice cultivars may produce momilactone B and release momilactone B into the culture solutions. In addition, the release level of momilactone B may depend on the production level of momilactone B in the seedlings, which may affect allelopathic potential of these rice cultivars because as a growth inhibitor, momilactone B is able to act as an allelochemical.     

Influence of shade timing on an Equisetum arvense L. population

Equisetum arvense L. is a perennial pteridophyte that grows in open sites. In Tokyo, the plant has photosynthetic shoots from late March to November. However, in some populations, these shoots are lost before summer because of shading by taller plants. To investigate the contribution of shoots that remain on the plant for a certain duration, in terms of the maintenance of the E.arvense population, tubers were cultivated under different light conditions and the dry weight of growth, photosynthetic rates and respiration rates were measured. Individual growth was simulated on the basis of matter production and its partitioning. Biomass at the start of the next growing season (the initial size) was seriously decreased by shading before July. However, shading after July had little effect on the initial size of the next season plants. Thus, E.arvense can maintain its population if its shoots are retained until summer.     

Phosphoproteome analysis of Lotus japonicus seeds

In this study, we report the first dataset of phosphoproteins of the seeds of a model plant, Lotus japonicus. This dataset might be useful in studying the regulatory mechanisms of seed germination in legume plants. By proteomic analysis of seeds following water absorption, we identified a total of 721 phosphopeptides derived from 343 phosphoproteins in cotyledons, and 931 phosphopeptides from 473 phosphoproteins in hypocotyls. Kinase‐specific prediction analyses revealed that different kinases were activated in cotyledons and hypocotyls. In particular, many peptides containing ATM‐kinase target motifs, X‐X‐pS/pT‐Q‐X‐X, were detected in cotyledons. Moreover, by real‐time RT‐PCR analysis, we found that expression of a homolog of ATM kinase is upregulated specifically in cotyledons, suggesting that this ATM‐kinase homolog plays a significant role in cell proliferation in the cotyledons of L. japonicus seeds. The data have been deposited to the ProteomeXchange with identifier PXD000053 ( http://proteomecentral.proteomexchange.org/dataset/PXD000053 ).     

Influence of habitat fragmentation on population structure of red deer in Croatia

The genetic structure of red deer populations is under strong influence of human activities such as game management and habitat fragmentation. Using multilocus genotypes from 193 geo-referenced individuals, we evaluated the population genetic structure of three red deer populations in Croatia. The effect of habitat fragmentation on genetic structure was tested using Bayesian non-spatial and spatial clustering methods. Our results indicate levels of genetic diversity similar to the ones previously reported by other authors for stable and appropriately managed populations within all populations analyzed. The spatial clustering model was able to detect the effect of habitat fragmentation on population differentiation, supporting the use of spatially explicit methods in landscape genetics, and giving important guidelines for future road planning.     

Impaired insulin signaling in endothelial cells reduces insulin-induced glucose uptake by skeletal muscle

In obese patients with type 2 diabetes, insulin delivery to and insulin-dependent glucose uptake by skeletal muscle are delayed and impaired. The mechanisms underlying the delay and impairment are unclear. We demonstrate that impaired insulin signaling in endothelial cells, due to reduced Irs2 expression and insulin-induced eNOS phosphorylation, causes attenuation of insulin-induced capillary recruitment and insulin delivery, which in turn reduces glucose uptake by skeletal muscle. Moreover, restoration of insulin-induced eNOS phosphorylation in endothelial cells completely reverses the reduction in capillary recruitment and insulin delivery in tissue-specific knockout mice lacking Irs2 in endothelial cells and fed a high-fat diet. As a result, glucose uptake by skeletal muscle is restored in these mice. Taken together, our results show that insulin signaling in endothelial cells plays a pivotal role in the regulation of glucose uptake by skeletal muscle. Furthermore, improving endothelial insulin signaling may serve as a therapeutic strategy for ameliorating skeletal muscle insulin resistance.     

The chemical-mediated allelopathic interaction between rice and barnyard grass

Aims

The possible involvement of the chemical-mediated interaction in allelopathy between rice and barnyard grass was investigated.

Methods

Effcts of rice seedlings and rice root exudate on the alleloapthic activity of barnyard grass were determined and a key compound invovled in the allelopathic interaction between rice and barnyard grass was isolated.

Results

Allelopathic activity of barnyard grass was increased by the presence of rice seedlings. Rice root exudates also elevated the allelopahtic activity of barnyard grass. A key compound, which increased the allelopathic activity of barnyard grass, in the rice root exudates was isolated and determined as momilactone B. Momilactone B increased the allelopathic activity of barnyard grass at concentrations greater than 3 μM, and increasing the momilactone B concentration increased the activity.

Conclusions

Momilactone B is known to act as a potent rice allelochemical and to possess strong growth inhibitory activity against barnyard grass. The present research suggests that barnyard grass may response to the presence of neighboring rice by sensing momilactone B in rice root exudates and increase allelopathic activity. Thus, momilactone B may not only act as a rice allelochemical but also play an important role in rice-induced allelopathy of barnyard grass. The induced-allelopathy may provide a competitive advantage for barnyard grass through the growth inhibition of competing plant species including rice. Barnyard grass allelopathy may be one of the inducible defense mechanisms by chemical-mediated plant interaction between rice and barnyard grass. Rice allelopathy was also reported to be increased by the presence of barnyard grass through increasing production and secretion of momilactone B into surrounding environments. During the evolutional process, rice and barnyard grass may have developed the chemical cross talk to activate the defense mechanisms against some biotic stress conditions by detection of certain key compounds.     

Homologous Pairing Activities of Two Rice RAD51 Proteins,RAD51A1 and RAD51A2

In higher eukaryotes, RAD51 functions as an essential protein in homologous recombination and recombinational repair of DNA double strand breaks. During these processes, RAD51 catalyzes homologous pairing between single-stranded DNA and double-stranded DNA. Japonica cultivars of rice (Oryza sativa) encode two RAD51 proteins, RAD51A1 and RAD51A2, whereas only one RAD51 exists in yeast and mammals. However, the functional differences between RAD51A1 and RAD51A2 have not been elucidated, because their biochemical properties have not been characterized. In the present study, we purified RAD51A1 and RAD51A2, and found that RAD51A2 robustly promotes homologous pairing in vitro. RAD51A1 also possesses homologous-pairing activity, but it is only about 10% of the RAD51A2 activity. Both RAD51A1 and RAD51A2 bind to ssDNA and dsDNA, and their DNA binding strictly requires ATP, which modulates the polymer formation activities of RAD51A1 and RAD51A2. These findings suggest that although both RAD51A1 and RAD51A2 have the potential to catalyze homologous pairing, RAD51A2 may be the major recombinase in rice.