Effects of starvation on larval growth, survival, and metamorphosis of Manila clam Ruditapes philippinarum

The effects of starvation on larval growth, survival, and metamorphosis of Manila clam Ruditapes philippinarum at the temperature of 19.6–21.6 °C, the salinity of 34‰ and pH of 8.0 were investigated from May 18 to July 18, 2006. In this study, the early, middle and late umbo-veliger larvae with the shell lengths of 100, 140, and 190 μm were subject to temporary food deprivation for up to 4.5, 20, and 25d at 0.5, 4, 5d intervals, followed by refeeding for the remaining of a 24, 20, 25d period, respectively. The results suggested that the larvae should have shown considerable tolerance to starvation due to their endogenous and exterior nutrition material, for larvae and time to the point-of-no-return (PNR: the threshold point during starvation after which larvae could no longer metamorphose even if food is provided) were calculated to be 4.25, 17.54, and 22.17d. As the starvation period prolonged, the mean shell length of larvae starved got close to constants at 1.5, 4, and 15d after starvation, which were different for larvae at different stages when starvation began, survival of larvae decreased, and was lower in treatments starved earlier in development than those starved later, for the early, middle and late umbo-veliger larvae, after 4.5, 20 and 25d of starvation period, few larvaes were alive. After starvation period, the alive larvaes were able to metamorphose and had a capability of compensatory growth when refeeding was given. Starvation not only affected metamorphosis rate, but also caused the delay in the time to metamorphosis and the decrease in the metamorphosed sizes. For example, for the continuously-fed larvae, duration to metamorphosis was 20.7d, for larvae with a size of 100-μm starved for up to 4d, larvae with a size of 140-μm starved for up to 16d, larvae with a size of 190-μm starved for up to 20d, duration to metamorphosis were 29.7, 31.7, and 37.7d, the delay in duration to metamorphosis were 9, 11, and 17d, respectively. Furthermore, importance of nutrition material for maintaining larval survival during starvation and the compensatory growth on larvae at the same feeding time were discussed.     

Effects of vessel compliance on flow pattern in porcine epicardial right coronary arterial tree

The compliance of the vessel wall affects hemodynamic parameters which may alter the permeability of the vessel wall. Based on experimental measurements, the present study established a finite element (FE) model in the proximal elastic vessel segments of epicardial right coronary arterial (RCA) tree obtained from computed tomography. The motion of elastic vessel wall was measured by an impedance catheter and the inlet boundary condition was measured by an ultrasound flow probe. The Galerkin FE method was used to solve the Navier–Stokes and Continuity equations, where the convective term in the Navier–Stokes equation was changed in the arbitrary Lagrangian–Eulerian (ALE) framework to incorporate the motion due to vessel compliance. Various hemodynamic parameters (e.g., wall shear stress—WSS, WSS spatial gradient—WSSG, oscillatory shear index—OSI) were analyzed in the model. The motion due to vessel compliance affects the time-averaged WSSG more strongly than WSS at bifurcations. The decrease of WSSG at flow divider in elastic bifurcations, as compared to rigid bifurcations, implies that the vessel compliance decreases the permeability of vessel wall and may be atheroprotective. The model can be used to predict coronary flow pattern in subject-specific anatomy as determined by noninvasive imaging.     

Development of SSR markers and analysis of diversity in Turkish populations of Brachypodium distachyon

Background  

Brachypodium distachyon (Brachypodium) is rapidly emerging as a powerful model system to facilitate research aimed at improving grass crops for grain, forage and energy production. To characterize the natural diversity of Brachypodium and provide a valuable new tool to the growing list of resources available to Brachypodium researchers, we created and characterized a large, diverse collection of inbred lines.     

Evaluation of Blastomere Biopsy Using a Mouse Model Indicates the Potential High Risk of Neurodegenerative Disorders in the Offspring

Preimplantation genetic diagnosis (PGD), used in clinical practice, is offered to couples that may suffer from a monogenetic disorder, chromosome aneuploidy, or X-linked disease. However, blastomere biopsy, as an indispensable manipulation during the PGD procedure has not been assessed for its long term health implications. Using a mouse model, we investigated the effect of blastomere biopsy of in vitro cultured four-cell embryos on preimplantation development efficiency, postnatal growth, and physiological and behavioral activity compared with control, non-biopsied embryos. The mice generated after blastomere biopsy showed weight increase and some memory decline compared with the control group. Further protein expression profiles in adult brains were analyzed by a proteomics approach. A total of 36 proteins were identified with significant differences between the biopsied and control groups, and the alterations in expression of most of these proteins have been associated with neurodegenerative diseases. Furthermore hypomyelination of the nerve fibers was observed in the brains of mice in the biopsied group. This study suggested that the nervous system may be sensitive to blastomere biopsy procedures and indicated an increased relative risk of neurodegenerative disorders in the offspring generated following blastomere biopsy. Thus, more studies should be performed to address the possible adverse effects of blastomere biopsy on the development of offspring, and the overall safety of PGD technology should be more rigorously assessed.Preimplantation genetic diagnosis (PGD)¹ has been one of the main clinical components of assisted reproductive technologies (ARTs) since 1990 (1). At present, infertile couples experiencing recurrent miscarriage or X chromosome-linked diseases are most likely to benefit from PGD.The treatment of human infertility by ARTs has gained widespread application, but it is disconcerting to many researchers that the clinical procedures used in ARTs are rapidly outpacing the underlying science. ART procedures are generally considered to be safe, but recent studies suggest a small increase in birth defects and low birth weights in ART children (2, 3). In addition, several clinical studies have reported an increased frequency of Beckwith-Wiedemann syndrome or Angelman syndrome caused by an imprinting defect among children conceived with ARTs (4, 5). These potential risks cause serious unease and justify more serious assessments of ARTs. However, moral, ethical, and legal issues complicate assessments of the genetic quality of ART-derived human conceptions, and significant genetic and demographic differences exist among couples participating in the ARTs, so a definitive assessment of the risks associated with this technology has been difficult to achieve. Therefore, appropriate animal models provide an important tool for studying potential effects of ARTs on the health and development of mammalian embryos (6).In many ART procedures, embryos are kept for a short time in a synthetic culture medium before transfer into their recipient mothers. Animal data have demonstrated that in vitro embryo culture and related procedures may be associated with epigenetic changes, perturbed genomic imprinting, and alterations in fetal growth (7). Some evidence also suggested that the culture environment may produce specific abnormalities during fetal and postnatal development (8–10). In the studies using mouse models, more marked changes in adult physiology, including onset of hypertension, were observed (11).As with other ARTs, the protocol required for PGD necessitates embryo manipulation and culture in vitro. However, in contrast to other ARTs, PGD involves embryo biopsy of one or two blastomeres at the eight-cell stage. Some studies have shown that blastomere biopsy does not have negative effects on embryo viability (12, 13), and offspring have been produced using embryo splitting technology, which is similar to the biopsy process, in at least six different domesticated species, including mouse (14), rabbit (15), sheep (16), bovine (17), goat (18), horse (19), pig (20), and in a preliminary non-human primate study one rhesus monkey (21). However, there is still a shortage of proof to convince the public that there is no potential risk to such animals conceived by this technology.To address this issue, we developed a mouse model to study the effects of blastomere biopsy on early embryo development and on postnatal physiological phenotype and behavior. A global proteomics method was also performed to study correlative protein expression profiles in adult brains and to indicate the possibility of neural degenerative disorders in adult conceived following biopsy technology.     

SUMO Modification Regulates BLM and RAD51 Interaction at Damaged Replication Forks

The gene mutated in Bloom''s syndrome, BLM, is important in the repair of damaged replication forks, and it has both pro- and anti-recombinogenic roles in homologous recombination (HR). At damaged forks, BLM interacts with RAD51 recombinase, the essential enzyme in HR that catalyzes homology-dependent strand invasion. We have previously shown that defects in BLM modification by the small ubiquitin-related modifier (SUMO) cause increased γ-H2AX foci. Because the increased γ-H2AX could result from defective repair of spontaneous DNA damage, we hypothesized that SUMO modification regulates BLM''s function in HR repair at damaged forks. To test this hypothesis, we treated cells that stably expressed a normal BLM (BLM+) or a SUMO-mutant BLM (SM-BLM) with hydroxyurea (HU) and examined the effects of stalled replication forks on RAD51 and its DNA repair functions. HU treatment generated excess γ-H2AX in SM-BLM compared to BLM+ cells, consistent with a defect in replication-fork repair. SM-BLM cells accumulated increased numbers of DNA breaks and were hypersensitive to DNA damage. Importantly, HU treatment failed to induce sister-chromatid exchanges in SM-BLM cells compared to BLM+ cells, indicating a specific defect in HR repair and suggesting that RAD51 function could be compromised. Consistent with this hypothesis, RAD51 localization to HU-induced repair foci was impaired in SM-BLM cells. These data suggested that RAD51 might interact noncovalently with SUMO. We found that in vitro RAD51 interacts noncovalently with SUMO and that it interacts more efficiently with SUMO-modified BLM compared to unmodified BLM. These data suggest that SUMOylation controls the switch between BLM''s pro- and anti-recombinogenic roles in HR. In the absence of BLM SUMOylation, BLM perturbs RAD51 localization at damaged replication forks and inhibits fork repair by HR. Conversely, BLM SUMOylation relieves its inhibitory effects on HR, and it promotes RAD51 function.     

松花江干流大型底栖动物群落结构与水质生物评价

于2010年春季（4-5月）、夏季（7-8月）和秋季（9-11月）,对松花江干流大型底栖动物群落结构进行调查研究,并利用生物指数对松花江干流水质进行评价.共采集到大型底栖动物16目36科116种,其中水生昆虫种类最多,为74种,属6目21科,占总数63.8%,年平均密度为66.80 ind·m^-2、生物量为24.30 g·m^-2.春、夏、秋季的平均密度以春季最高 (90.52 ind·m^-2),秋季(61.26 ind·m^-2)次之,夏季(48.63 ind·m^-2)最低;平均生物量以秋季最高(35.35 g·m^-2),夏季(23.12 g·m^-2)次之,春季(14.41 g·m^-2)最低.Shannon指数、Pielou均匀度指数、Simpson指数均以春季最高,夏季与秋季相近.各断面微生境共有种不多, 物种相似性不高,最大仅为60%;功能摄食群种类数相近,共有撕食者26种,收集者32种,刮食者28种,捕食者30种.采用BI生物指数和FBI生物指数对松花江干流水质的评价结果基本一致,并与化学监测结果基本吻合.松花江干流哈尔滨断面以上水质一般,哈尔滨以下断面水质在不同时期处于污染或严重污染状态.推测大顶子山航电枢纽的修建已对大型底栖动物的物种组成、群落结构造成了较大影响.     

Colonization study of gfp-tagged Achromobacter marplatensis strain in sugar beet

This study details the introduction of a gfp marker into an endophytic bacterial strain (Achromobacter marplatensis strain 17, isolated from sugar beet) to monitor its colonization of sugar beet (Beta. vulgaris L.). Stability of the plasmid encoding the gfp was confirmed in vitro for at least 72 h of bacterial growth and after the colonization of tissues, under nonselective conditions. The colonization was observed using fluorescence microscopy and enumeration of culturable endophytes in inoculated sugar beet plants that grew for 10 or 20 days. gfp-Expressing strains were re-isolated from the inner tissues of surface-sterilized roots and stems of inoculated plants, and the survival of the Achromobacter marplatensis 17:gfp strain in plants 20 days after inoculation, even in the absence of selective pressure, suggests that it is good colonizer. These results also suggest that this strain could be a useful tool for the delivery of enzymes or other proteins into plants. In addition, the study highlights that sugar beet plants can be used effectively for detailed in vitro studies on the interactions between A. marplatensis strain 17 and its host, particularly if a gfp-tagged strain of the pathogen is used.     

On the sustainability of a reintroduced Crested Ibis population in Qinling Mountains,Shaanxi, Central China

Reintroduction projects aim to reestablish a self‐sustaining population of an endangered species within its historical range. Adequate post‐release monitoring by gathering demographic data is important to evaluate the success of a reintroduction. Survival and reproduction rates of a reintroduced population can be compared with a self‐sustaining wild population to evaluate the success of a reintroduction. In early 2007, Nipponia nippon (Crested Ibis) was reintroduced into the Qinling Mountains (Shaanxi, Central China). In this study, we attempt to evaluate the demographic status of the reintroduced population. Age‐specific survival rates of 56 released adults and 77 wild‐born fledglings were estimated using mark‐recapture data obtained from 2007 to 2014. Survival rates for the yearlings (0.599, with 95% confidence interval [CI]: 0.467–0.719) were lower than the estimates from a wild population in Yangxian County, but the survival rates of the adults (0.678, with 95% CI: 0.603–0.745) were similar. The number of breeding pairs gradually increased since 2008, although breeding success (52.5%) was somewhat less than that of the wild population (67.6%). The stochastic estimation of population growth rate (1.084 with 95% CI: 1.069–1.098) and population size (5‐fold increase) estimated from an age‐classified Leslie matrix indicate that the reintroduced population of the Crested Ibis is more likely in regulation phase over the next 25 years. We conclude that the reintroduction of the Crested Ibis in Qinling Mountains has great promise, and progress toward a self‐sustaining population has been made under some interventions. Governments, local communities, and scientists need to facilitate habitat restoration for the long‐term survival of this endangered species.