The mechanism of stamen movement in <Emphasis Type="Italic">Chimonanthus praecox</Emphasis> (Calycanthaceae): differential cell growth rates on the adaxial and abaxial surfaces of filaments after flower opening

In flowers of Chimonanthus (Calycanthaceae), stamen movements have been known for 150 years. Stamens are initially recurved when flowers open. Subsequently, within approximately 48 h, the stamens gradually turn upright and eventually enclose the gynoecium. However, the exact mechanism involved in this process is still unresolved. In this study, we found that in recurved stamens at the female stage the cell lengths in the epidermal and hypodermal tissue of the abaxial surfaces were significantly smaller than those of the adaxial surfaces. In erect stamens, however, no significant difference in cell length between the hypodermal tissues of both surfaces was found. Although the difference in cell length between the epidermal tissues for erect stamens was significant, it was smaller than that in recurved filaments. We found no variations in cell number between the epidermal tissues or between the hypodermal tissues among recurved and erect stamens. Thus, we conclude that in Chimonanthus the differential cell growth rates between the adaxial and abaxial surfaces of filaments could account for the gradual inward stamen movement following flower opening rather than cell division. Furthermore, application of indole-3-acetic acid (IAA) and gibberellic acid (GA₃) to intact flowers in vitro or the wounding of stigmas significantly promoted the stamen erection rate. Surprisingly, we did not observe any effect on this movement following hand-pollination. Different patterns of stamen movement in Calycanthaceae and their implications for reproductive biology are also discussed.     

Cell-free formation of RNA granules: low complexity sequence domains form dynamic fibers within hydrogels

Eukaryotic cells contain assemblies of RNAs and proteins termed RNA granules. Many proteins within these bodies contain KH or RRM RNA-binding domains as well as low complexity (LC) sequences of unknown function. We discovered that exposure of cell or tissue lysates to a biotinylated isoxazole (b-isox) chemical precipitated hundreds of RNA-binding proteins with significant overlap to the constituents of RNA granules. The LC sequences within these proteins are both necessary and sufficient for b-isox-mediated aggregation, and these domains can undergo a concentration-dependent phase transition to a hydrogel-like state in the absence of the chemical. X-ray diffraction and EM studies revealed the hydrogels to be composed of uniformly polymerized amyloid-like fibers. Unlike pathogenic fibers, the LC sequence-based polymers described here are dynamic and accommodate heterotypic polymerization. These observations offer a framework for understanding the function of LC sequences as well as an organizing principle for cellular structures that are not membrane bound.     

Study on the granular characteristics of starches separated from Chinese rice cultivars

Granule size distribution, the relative crystallinity, morphology and thermal degradation of starches from 10 different non-waxy rice cultivars were measured in present study. The relationships between granular structure and thermogravimetric parameters of tested starches were evaluated using Pearson correlation analysis. The range of median size for rice starches was 6.23-7.81 μm. The relative crystallinity of 10 non-waxy rice starches ranged from 20.4% to 33.4%. The range of activation energy from different rice starches was between 155.6 and 201.5 kJ/mol. The Pearson correlation results showed that the relative crystallinity was positively correlated (r = 0.6750, p < 0.05) with the percentage of branch chains with DP12-23. Furthermore, the activation energy of the rice starches showed a positive correlation (r = 0.7903, p < 0.01) with relative crystallinity.     

Chronic hypoxia exposure during pregnancy is associated with a decreased active nursing activity in mother and an abnormal birth weight and postnatal growth in offspring of rats

Stress during pregnancy is known to have a significant impact on animal's behavior and offspring development. The effects of gestational hypoxia on maternal behavior have not been studied. In the present study, we investigated the effects of gestational hypoxia exposure on dam's maternal behavior, offspring's growth and plasma corticosterone levels after parturition in rats. Altitude hypoxia (3 and 5 km) was simulated in the hypobaric chambers during the last week of pregnancy and the effects were compared to those found in controls exposed at sea level. We found that gestational hypoxia significantly decreased dam's arched-back nursing activity across the lactation period. The effect was more profound in 5 km group. Gestational hypoxia also altered other maternal behaviors such as blanket and passive nursing. Hypoxia exposure was associated with abnormal birth weight and postnatal growth in pups, with a significantly higher and lower birth weight than control found in 3 and 5 km groups, respectively, and accelerated growth in both stressed groups. Gestational hypoxia exposure significantly elevated plasma corticosterone levels in dams at the time of weaning and in pups across the measurement days. Taken together, the present results indicate that hypoxia, particularly severe hypoxia during the late phase of pregnancy has a significantly adverse impact on animal's behavior, endocrine function and offspring development. The higher birth weight found in the offspring of 3 km group suggests a compensatory system counteracting with the inhibitory effects of hypoxia on fetus growth at this altitude.     

ABCB6 mutations cause ocular coloboma

Ocular coloboma is a developmental defect of the eye and is due to abnormal or incomplete closure of the optic fissure. This disorder displays genetic and clinical heterogeneity. Using a positional cloning approach, we identified a mutation in the ATP-binding cassette (ABC) transporter ABCB6 in a Chinese family affected by autosomal-dominant coloboma. The Leu811Val mutation was identified in seven affected members of the family and was absent in six unaffected members from three generations. A LOD score of 3.2 at θ = 0 was calculated for the mutation identified in this family. Sequence analysis was performed on the ABCB6 exons from 116 sporadic cases of microphthalmia with coloboma (MAC), isolated coloboma, and aniridia, and an additional mutation (A57T) was identified in three patients with MAC. These two mutations were not present in the ethnically matched control populations. Immunostaining of transiently transfected, Myc-tagged ABCB6 in retinal pigment epithelial (RPE) cells showed that it localized to the endoplasmic reticulum and Golgi apparatus of RPE cells. RT-PCR of ABCB6 mRNA in human cell lines and tissue indicated that ABCB6 is expressed in the retinae and RPE cells. Using zebrafish, we show that abcb6 is expressed in the eye and CNS. Morpholino knockdown of abcb6 in zebrafish produces a phenotype characteristic of coloboma and replicates the clinical phenotype observed in our index cases. The knockdown phenotype can be corrected with coinjection of the wild-type, but not mutant, ABCB6 mRNA, suggesting that the phenotypes observed in zebrafish are due to insufficient abcb6 function. Our results demonstrate that ABCB6 mutations cause ocular coloboma.     

Microsatellite primers for the endangered aquatic herb, Ottelia acuminata (Hydrocharitaceae)

? Premise of the study: Microsatellite primers were developed in the endangered aquatic herb, Ottelia acuminata, to characterize its genetic diversity and understand its population structure. ? Methods and Results: Eight polymorphic microsatellite markers were developed from two populations of O. acuminata in China. The number of alleles per locus ranged from one to 15; the observed and expected heterozygosities ranged from 0 to 0.885 and from 0 to 0.888, respectively, in the two populations. Selected loci also amplified successfully in O. sinensis. ? Conclusions: These microsatellite markers will facilitate further studies on the conservation genetics and evolutionary history of O. acuminata.     

The antiepileptic drug valproic Acid restores T cell homeostasis and ameliorates pathogenesis of experimental autoimmune encephalomyelitis

Maintaining a constant number and ratio of immune cells is one critical aspect of the tight regulation of immune homeostasis. Breakdown of this balance will lead to autoimmune diseases such as multiple sclerosis (MS). The antiepileptic drug valproic acid (VPA) was reported to regulate the growth, survival, and differentiation of many cells. However, its function in T cell homeostasis and MS treatment remains unknown. In this study, VPA was found to reduce spinal cord inflammation, demyelination, and disease scores in experimental autoimmune encephalomyelitis, a mouse model of MS. Further study indicated that VPA induces apoptosis in activated T cells and maintains the immune homeostasis. This effect was found to be mainly mediated by the caspase-8/caspase-3 pathway. Interestingly, this phenomenon was also confirmed in T cells from normal human subjects and MS patients. Considering the long history of clinical use and our new findings, we believe VPA might be a safe and effective therapy for autoimmune diseases, such as multiple sclerosis.     

Isoleucine or valine deprivation stimulates fat loss via increasing energy expenditure and regulating lipid metabolism in WAT

There has been a growing interest in controlling body weight by increasing dietary levels of leucine recently. By contrast, we have focused on studying the effect of deficiency of branched-chain amino acids (BCAAs) leucine on lipid metabolism. We previously have shown that mice fed a leucine-deficient diet for 7 days exhibit significant changes in lipid metabolism as demonstrated by suppressed lipogenesis in the liver and increased fat mobilization in white adipose tissue, the latter of which was found to be caused by increased lipolysis in WAT and uncoupling protein 1 expression in brown adipose tissue. The goal of our current study is to investigate whether the above effects of leucine deficiency can be generalized to the deficiency of other BCAAs including valine and isoleucine. In our current study, we show that valine or isoleucine deficiency has similar effects on reducing fat mass to leucine deprivation, in a similar manner as those observed during leucine deprivation.