Overexpression of HBK3, a class I KNOX homeobox gene, improves the development of Norway spruce (Picea abies) somatic embryos

In order to investigate the effects of HBK3, a spruce gene member of the class I KNOX family, during somatic embryogenesis, sense (HBK3-S) and antisense (HBK3-A) Norway spruce (Picea abies) lines were generated. Somatic embryos produced from these lines were then analysed at morphological and structural levels. Compared with control, differentiation of immature somatic embryos from pro-embryogenic masses (PEMs) was accelerated in lines overexpressing HBK3 (HBK3-S). Such immature embryos showed enlarged embryogenic heads and were able to produce fully developed cotyledonary embryos at higher frequency. Furthermore, HBK3-S embryos had enlarged shoot apical meristems (SAMs) and enlarged expression pattern of PgAGO, a molecular marker gene specific to meristematic cells. Lines in which HBK3 (HBK3-A) was down-regulated had reduced ability to produce immature somatic embryos from PEMs and were not able to complete the maturation processes. To assess the function of HBK3 in comparison with that of angiosperm KNOX genes, this gene was ectopically expressed in Arabidopsis plants. As observed for spruce, Arabidopsis embryos overexpressing HBK3 had enlarged meristems and enlarged expression pattern of SHOOTMERISTEMLESS, a SAM molecular marker gene. In addition, transformed embryos were able to germinate at a higher rate and the resulting plants showed a variety of phenotypic aberrations, including abnormal leaves and reduced apical dominance. Overall, these data confirm the importance of KNOTTED genes during development and reveal the participation of HBK3 in conifer embryogeny. Furthermore, the results show redundant functions of this gene during embryonic growth of spruce and Arabidopsis, but not during post-embryonic growth.     

Bcl-2 family proteins are essential for platelet survival

Platelets are relatively short-lived, anucleated cells that are essential for proper hemostasis. The regulation of platelet survival in the circulation remains poorly understood. The process of platelet activation and senescence in vivo is associated with processes similar to those observed during apoptosis in nucleated cells, including loss of mitochondrial membrane potential, caspase activation, phosphatidylserine (PS) externalization, and cell shrinkage. ABT-737, a potent antagonist of Bcl-2, Bcl-X(L), and Bcl-w, induces apoptosis in nucleated cells dependent on these proteins for survival. In vivo, ABT-737 induces a reduction of circulating platelets that is maintained during drug therapy, followed by recovery to normal levels within several days after treatment cessation. Whole body scintography utilizing ([111])Indium-labeled platelets in dogs shows that ABT-737-induced platelet clearance is primarily mediated by the liver. In vitro, ABT-737 treatment leads to activation of key apoptotic processes including cytochrome c release, caspase-3 activation, and PS externalization in isolated platelets. Despite these changes, ABT-737 is ineffective in promoting platelet activation as measured by granule release markers and platelet aggregation. Taken together, these data suggest that ABT-737 induces an apoptosis-like response in platelets that is distinct from platelet activation and results in enhanced clearance in vivo by the reticuloendothelial system.     

Preliminary findings of age and male sexual characteristics andand potential effect to semen characteristics and cryopreservation of the critically endangered Bornean orangutan in Malaysia

Primates - Bornean orangutan is a critically endangered non-human primate; however, the threat of extinction is not merely from poaching and habitat loss. Orangutan survival is also threatened by...     

Systematic analysis of HD-ZIP transcription factors in sesame genome and gene expression profiling of SiHD-ZIP class I entailing drought stress responses at early seedling stage

Molecular Biology Reports - Sesame is an ancient oilseed crop, known for its high oil content and quality. Its sensitivity to drought at early seedling stage is one of the limiting factors...     

Exogenous application of thiamin promotes growth and antioxidative defense system at initial phases of development in salt-stressed plants of two maize cultivars differing in salinity tolerance

The effects of thiamin (Thi) applied as seed soaking or foliar spray on some key physiological parameters were investigated in two differentially salt-responsive maize (Zea mays L.) cultivars, DK 5783 and Apex 836 F1, exposed to saline stress in two different experiments. An initial experiment (germination experiment) was designed to identify appropriate doses of Thi which could lessen the deleterious effects of salt on plants and screen all available maize cultivars for their differential tolerance to salt stress (100 mM NaCl). The seeds of nine maize cultivars were soaked for 24 h in solutions containing six levels of Thi (25, 50, 75, 100, 125 and 150 mg l^?1). Based on the results obtained from the germination experiment, maize cultivar DK 5783 was found to be the most salt tolerant and Apex 836 as the most sensitive cultivar. Also, of six Thi levels used, two levels (100 and 125 mg l^?1) were chosen for subsequent studies. In the second experiment (glasshouse experiment), two maize cultivars, DK 5783 (salt tolerant) and Apex 836 (salt sensitive) were subjected to saline regime (100 mM NaCl) and two levels of Thi (100 and 125 mg l^?1) applied as foliar spray. Salt stress markedly suppressed shoot and root dry mass, total chlorophylls (“a” + “b”), leaf water potential and maximum fluorescence yield (Fv/Fm) in the plants of both maize cultivars, but it increased proline accumulation, leaf osmotic pressure, malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) concentrations, electrolyte leakage (EL) as well as activities of some key antioxidant enzymes, superoxide dismutase (SOD; EC. 1.15.1.1), peroxidase (POD; EC. 1.11.1.7) and catalase (CAT; EC. 1.11.1.6). Salt-induced reduction in plant growth parameters was higher in the salt-sensitive cultivar, Apex 836, which was found to be associated with relatively increased EL, and MDA and H₂O₂ levels, and decreased activities of the key antioxidant enzymes. Application of Thi as seed soaking or foliar spray partly mitigated the deleterious effects of salinity on plants of both maize cultivars. The most promising effect of Thi on alleviation of adverse effects of salt stress on maize plants was found when it was applied as foliar spray at 100 mg l^?1. Thiamin application considerably reduced tissue Na⁺ concentration, but improved those of N, P, Ca²⁺ and K⁺ in the salt-stressed maize plants. Exogenously applied thiamin-induced growth improvement in maize plants was found to be associated with reduced membrane permeability, MDA and H₂O₂ levels, and altered activities of some key antioxidant enzymes such as CAT, SOD and POD as well as increased photosynthetic pigment concentration under saline regime.     

黄土高原半干旱偏旱区草粮轮作田土壤水分恢复效应模拟

采用实地调查和EPIC模型相结合的方法,模拟研究了黄土高原半干旱偏旱区不同草粮轮作模式的土壤水分恢复效应.结果表明：多年生苜蓿地和苜蓿翻耕后种植粮食作物农田0～10 m土层土壤湿度调查值与模拟值间的相关系数均超过0.9（P<0.01）,相对均方根误差在0.05～0.16,相对误差均低于10%;模拟与实测的土壤湿度剖面分布变化趋势一致.在黄土高原半干旱偏旱区,苜蓿地深层土壤干层恢复难度较大,在种植苜蓿期间应避免8～10 m土层土壤湿度降到5.7%以下.苜蓿地适宜种植年限为4～6 a,最长不应超过8 a.苜蓿翻耕后适宜采用马铃薯→马铃薯→春小麦轮作模式进行土壤水分恢复,32～33 a后可以再次种植苜蓿.     

Optimization of chemical induction conditions for human herpesvirus 8 (HHV-8) reactivation with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) from latently-infected BC-3 cells

Human herpesvirus 8 (HHV-8) persists as episomal DNA in latently-infected cells and can establish two alternative life cycles, latent or lytic. 12-O-tetradecanoyl-phorbol-13-acetate (TPA) is a known inducer of HHV-8 in several human primary effusion lymphoma cell lines and has been widely used for HHV-8 reactivation; however, induction conditions have differed, resulting in varying levels of virus expression. We have used HHV-8 latently-infected BC-3 cells as a model to determine critical parameters for optimizing virus reactivation by TPA. We found that cell growth properties and drug treatment conditions were important for maximum reactivation of HHV-8. Addition of TPA to cells in the early log phase of a sigmoidal growth curve, which was tightly associated with high percentage of the cells in early S phase and with lower histone deacetylase activity in the cells, provided the optimum cell conditions for latent virus to switch to lytic replication. Furthermore, increasing TPA concentration (up to 320 ng per ml) at 48 h exposure time resulted in increased virus production. The results demonstrate the use of a step-wise strategy with chemical induction that may facilitate broad detection of latent DNA viruses and novel virus discovery.     

The use of race, ethnicity and ancestry in human genetic research

Post-Human Genome Project progress has enabled a new wave of population genetic research, and intensified controversy over the use of race/ethnicity in this work. At the same time, the development of methods for inferring genetic ancestry offers more empirical means of assigning group labels. Here, we provide a systematic analysis of the use of race/ethnicity and ancestry in current genetic research. We base our analysis on key published recommendations for the use and reporting of race/ethnicity which advise that researchers: explain why the terms/categories were used and how they were measured, carefully define them, and apply them consistently. We studied 170 population genetic research articles from high impact journals, published 2008-2009. A comparative perspective was obtained by aligning study metrics with similar research from articles published 2001-2004. Our analysis indicates a marked improvement in compliance with some of the recommendations/guidelines for the use of race/ethnicity over time, while showing that important shortfalls still remain: no article using 'race', 'ethnicity' or 'ancestry' defined or discussed the meaning of these concepts in context; a third of articles still do not provide a rationale for their use, with those using 'ancestry' being the least likely to do so. Further, no article discussed potential socio-ethical implications of the reported research. As such, there remains a clear imperative for highlighting the importance of consistent and comprehensive reporting on human populations to the genetics/genomics community globally, to generate explicit guidelines for the uses of ancestry and genetic ancestry, and importantly, to ensure that guidelines are followed.     

A Partial Least Squares based algorithm for parsimonious variable selection

Background

We consider the following problem: Given an undirected network and a set of sender-receiver pairs, direct all edges such that the maximum number of "signal flows" defined by the pairs can be routed respecting edge directions. This problem has applications in understanding protein interaction based cell regulation mechanisms. Since this problem is NP-hard, research so far concentrated on polynomial-time approximation algorithms and tractable special cases.

Results

We take the viewpoint of parameterized algorithmics and examine several parameters related to the maximum signal flow over vertices or edges. We provide several fixed-parameter tractability results, and in one case a sharp complexity dichotomy between a linear-time solvable case and a slightly more general NP-hard case. We examine the value of these parameters for several real-world network instances.

Conclusions

Several biologically relevant special cases of the NP-hard problem can be solved to optimality. In this way, parameterized analysis yields both deeper insight into the computational complexity and practical solving strategies.