Preterm birth without progesterone withdrawal in 15-hydroxyprostaglandin dehydrogenase hypomorphic mice

Parturition is a complex mammalian physiological process whose fundamental determinants have remained elusive. The increasing incidence of human preterm birth, a leading cause of infant mortality, highlights the importance of further understanding mechanisms regulating the timing of birth. Parturition is initiated in most nonprimate mammals, including mice, through a decrease in circulating progesterone caused by elevated prostaglandins. In humans, other higher primates, and guinea pigs, no consistent decrease in circulating progesterone occurs before the onset of labor. The divergence in endocrine control of labor initiation between most mammals compared with the great apes and guinea pigs gives rise to the question: how could a mechanism for the initiation of labor not requiring the withdrawal of progesterone evolve? Here, we genetically modulate prostaglandin signaling to determine the role of prostaglandin catabolism in the timing of birth. We find spontaneous preterm labor in the absence of progesterone withdrawal in 15-hydroxyprostaglandin dehydrogenase hypomorphic mice. The onset of labor in these hypomorphic mice is preceded by prematurely increased concentrations of prostaglandin E(2) and F(2alpha). Moreover, genetic crosses demonstrate a role for fetal genotype in birth timing. Together, these findings demonstrate a 15-hydroxyprostaglandin dehydrogenase-dependent shift in the physiology of murine parturition to one resembling the physiology of higher primates. Thus, endocrine control of labor has the capacity to plastically adapt to changes in genetically determined prostaglandin signals.     

盾叶薯蓣营养器官薯蓣皂甙元含量的动态变化

利用高效液相色谱(HPLC)法对盾叶薯蓣营养器官特别是根状茎中薯蓣皂甙元含量的动态变化、品种之间的差异以及雌雄株之间的差异进行了研究。结果表明：实生苗根状茎中薯蓣皂甙元的含量,2年生高于1年生;根茎营养繁殖的2年生根状茎中皂甙元的含量高于1年生的含量;花叶品种的含量高于绿叶品种的含量;雄株的含量比雌株的含量高。在地上的缠绕茎和叶中没有检测到薯蓣皂甙元。由根茎繁殖的1年生根状茎前期皂甙元含量增加缓慢,后期增加较快;2年生根状茎盛花期含量最高,开花后期含量最低,随后含量逐渐增加。为此应在花叶品种中选择产量高、抗性强的品种作为栽培品种。合适的采挖期仍以地上缠绕茎枯萎期为宜。     

Incorporating prior knowledge of gene functional groups into regularized discriminant analysis of microarray data

MOTIVATION: Discriminant analysis for high-dimensional and low-sample-sized data has become a hot research topic in bioinformatics, mainly motivated by its importance and challenge in applications to tumor classifications for high-dimensional microarray data. Two of the popular methods are the nearest shrunken centroids, also called predictive analysis of microarray (PAM), and shrunken centroids regularized discriminant analysis (SCRDA). Both methods are modifications to the classic linear discriminant analysis (LDA) in two aspects tailored to high-dimensional and low-sample-sized data: one is the regularization of the covariance matrix, and the other is variable selection through shrinkage. In spite of their usefulness, there are potential limitations with each method. The main concern is that both PAM and SCRDA are possibly too extreme: the covariance matrix in the former is restricted to be diagonal while in the latter there is barely any restriction. Based on the biology of gene functions and given the feature of the data, it may be beneficial to estimate the covariance matrix as an intermediate between the two; furthermore, more effective shrinkage schemes may be possible. RESULTS: We propose modified LDA methods to integrate biological knowledge of gene functions (or variable groups) into classification of microarray data. Instead of simply treating all the genes independently or imposing no restriction on the correlations among the genes, we group the genes according to their biological functions extracted from existing biological knowledge or data, and propose regularized covariance estimators that encourages between-group gene independence and within-group gene correlations while maintaining the flexibility of any general covariance structure. Furthermore, we propose a shrinkage scheme on groups of genes that tends to retain or remove a whole group of the genes altogether, in contrast to the standard shrinkage on individual genes. We show that one of the proposed methods performed better than PAM and SCRDA in a simulation study and several real data examples.     

A new role for cathelicidin in ulcerative colitis in mice

Cathelicidin, an antimicrobial peptide of the innate immune system, modulates microbial growth, wound healing, and inflammation. However, its association with inflammatory bowel diseases (IBDs) is unknown. Our objective was to determine whether cathelicidin would exert a modulatory effect on the progression of IBD and, if so, investigate the mechanism of action through which this effect occurred. We evaluated the potential for a synthetic cathelicidin, the mouse cathelin-related antimicrobial peptide (mCRAMP), to prevent the initiation and promote the healing of lesions from inflammatory colitis that was experimentally induced in mice with dextran sulfate sodium (DSS). During the experiment, mCRAMP was given: (i) as a parallel treatment starting together with 3% DSS feeding, and (ii) as a posttreatment starting 7 days after 3% DSS feeding. The body weight, fecal microflora populations, clinical symptoms, and histologic findings of colonic tissues were measured. Relative gene expression of mucins (MUC1, MUC2, MUC3, and MUC4) in colonic tissues was determined by real-time polymerase chain reaction. Intrarectal administration of mCRAMP ameliorated DSS-induced colitis with negligible effects on mucosal healing. The peptide also significantly reduced the increased number of fecal microflora in colitis animals. It reversed the decline of colonic mucus thickness during colitis through upregulation of the expression of mucin genes. Treatment with mCRAMP also prevented colitis development by suppressing the induction of apoptosis by DSS. The current study demonstrates for the first time that intrarectal administration of cathelicidin may be a novel therapeutic option for IBDs.     

Sequential steps in synaptic targeting of sensory afferents are mediated by constitutive and developmentally regulated glycosylations of CAMs.

Sensory afferents in the leech are labeled with both constitutive and developmentally regulated glycosylations (markers) of their cell adhesion molecules (CAMs). Their constitutive mannose marker, recognized by Lan3-2 monoclonal antibody (mAb), mediates the formation of their diffuse central arbors. We show that, at the ultrastructural level, these arbors consist of large, loosely organized axons rich with filopodia and synaptic vesicles. Perturbing the mannose-specific adhesion of this first targeting step leads to a gain in cell-cell contact but a loss of filopodia and synaptic vesicles. During the second targeting step, galactose markers divide afferents into different subsets. We focus on the subset labeled by the marker recognized by Laz2-369 mAb. Initially, the galactose marker appears where afferents contact central neurons. Subsequently it spreads proximally and distally, covering the entire afferent surface. Afferents now gain cell-cell contact, with central neurons and self-similar afferents, but lose filopodia and synaptic vesicles. Extant synaptic vesicles prevail where afferents are apposed to central neurons. These neurons develop postsynaptic densities and en passant synapses are forming. Perturbing the galactose-specific adhesion of this second targeting step causes a loss of cell-cell contact but a gain in filopodia and synaptic vesicles, essentially returning afferents to the first targeting step. The transformation of afferent growth, progressing from mannose- to galactose-specific adhesion, is consistent with a change from cell-matrix to cell-cell adhesion. By performing opposing functions in a temporal sequence, constitutive and developmentally regulated glycosylations of CAMs collaborate in the synaptogenesis of afferents and the consolidation of self-similar afferents.     

Caveolin‐1 down‐regulation is required for Wnt5a‐Frizzled 2 signalling in Ha‐RasV12‐induced cell transformation

Caveolin‐1 (Cav1) is down‐regulated during MK4 (MDCK cells harbouring inducible Ha‐Ras^V12 gene) transformation by Ha‐Ras^V12. Cav1 overexpression abrogates the Ha‐Ras^V12‐driven transformation of MK4 cells; however, the targeted down‐regulation of Cav1 is not sufficient to mimic this transformation. Cav1‐silenced cells, including MK4/shCav1 cells and MDCK/shCav1 cells, showed an increased cell area and discontinuous junction‐related proteins staining. Cellular and mechanical transformations were completed when MDCK/shCav1 cells were treated with medium conditioned by MK4 cells treated with IPTG (MK4+I‐CM) but not with medium conditioned by MK4 cells. Nanoparticle tracking analysis showed that Ha‐Ras^V12‐inducing MK4 cells increased exosome‐like microvesicles release compared with their normal counterparts. The cellular and mechanical transformation activities of MK4+I‐CM were abolished after heat treatment and exosome depletion and were copied by exosomes derived from MK4+I‐CM (MK4+I‐EXs). Wnt5a, a downstream product of Ha‐Ras^V12, was markedly secreted by MK4+I‐CM and MK4+I‐EXs. Suppression of Wnt5a expression and secretion using the porcupine inhibitor C59 or Wnt5a siRNA inhibited the Ha‐Ras^V12‐ and MK4+I‐CM‐induced transformation of MK4 cells and MDCK/shCav1 cells, respectively. Cav1 down‐regulation, either by Ha‐Ras^V12 or targeted shRNA, increased frizzled‐2 (Fzd2) protein levels without affecting its mRNA levels, suggesting a novel role of Cav1 in negatively regulating Fzd2 expression. Additionally, silencing Cav1 facilitated the internalization of MK4+I‐EXs in MDCK cells. These data suggest that Cav1‐dependent repression of Fzd2 and exosome uptake is potentially relevant to its antitransformation activity, which hinders the activation of Ha‐Ras^V12‐Wnt5a‐Stat3 pathway. Altogether, these results suggest that both decreasing Cav1 and increasing exosomal Wnt5a must be implemented during Ha‐Ras^V12‐driven cell transformation.     

Sphingosylphosphorylcholine-induced contraction of feline ileal smooth muscle cells is mediated by Gαi3 protein and MAPK

We studied the mechanism of sphingosylphosphorylcholine (SPC)-induced contraction in feline ileal smooth muscle cells. Western blotting revealed that G protein subtypes of Gα_i1, Gα_i3 and Gα_o existed in feline ileum. Gα_i3 antibody penetration into permeabilized cells decreased SPC-induced contraction. In addition, incubation of [³⁵S]guanosine 5′-O-(3-thiotriphosphate) ([³⁵S]GTPγS) with membrane fraction increased its binding to Gα_i3 subtype after SPC treatment, suggesting that the signalling pathways invoked by SPC were mediated by Gα_i3 protein. MAPK kinase (MEK) inhibitor PD98059 blocked the contraction significantly, but p38 mitogen-activated protein kinase (MAPK) inhibitor SB202190 did not. Chelerythrine and neomycin also inhibited the contraction. However, cotreatment of PD98059 and chelerythrine showed no significant difference. Phosphorylation of p44/42 MAPK was increased by SPC treatment, which was reversed by pretreatment of inhibitors of signalling molecules that decreased SPC-induced contraction previously. The same result was obtained in the assay of MAPK activity.     

Sequence Heterogeneity in Closed Simian Virus 40 Deoxyribonucleic Acid

The heteroduplex molecules formed by self-annealing of denatured, singly nicked simian virus 40 (SV40) deoxyribonucleic acid (DNA) prepared from closed viral DNA were examined by formamide-protein film electron microscopy to test the DNA for sequence homogeneity. Sequence inhomogeneity appears in the heteroduplexes as single-strand loops. These result from sequence deletion or from sequence substitution, if regions greater than 50 nucleotides are involved. The undenatured DNA from viruses passaged twice at multiplicities of infection much less than 1 plaque-forming unit (PFU) per cell appeared to be homogeneous in size. The heteroduplexes formed by this DNA indicated that approximately 2% of the molecules carried deletions, but that substitutions were below the level of detection. In contrast, undenatured DNA from viruses grown by passaging undiluted lysates seven times or by infection with stock virus at a multiplicity of infection of 5 PFU per cell contained a large frequency of molecules shorter than the full length. The heteroduplex samples indicated that 12 and 7% of the undenatured material contained base substitutions, and 13 and 11% contained deletions. The deletions and substitutions appear to occur in separate molecules. Length measurements on heteroduplexes displaying the loop characteristic of substitutions have established that these molecules are from true sequence substitutions, and not from adjacent or overlapping deletions. More than 80% of the molecules carrying substitutions are shorter than the native SV40 length. On the average, the substituted sequence is about 20% of the length of SV40, but it replaces a sequence about 30% of the native length. The substituted sequences may be host cell nuclear DNA, possibly arising from integration of SV40 into the chromosome followed by excision of the SV40 DNA together with chromosomal DNA.     

滇金丝猴（Rhinopithecusbieti）现状及其保护对策研究

滇金丝猴（Ｒｈｉｎｏｐｉｔｈｅｃｕｓｂｉｅｔｉ）是我国特有的珍稀濒危动物,生活在海拔３８００～４３００ｍ的原始冷杉林中,但有时也会在４３００～４７００ｍ的低矮灌丛、草甸和流石滩上活动达数小时之久,甚至能跨越近千米的无林高海拔地带,因而它们是海拔分布最高的非人灵长类。松萝是它们的主要食物,取食松萝的时间占总取食时间的９１％。猴群活动范围可达近百平方公里。笔者在历时８年的野外考察中,已查明这一物种的全部现存自然种群只有１３个,分布在云南的德钦、兰坪、潍西、丽江和西藏的芒康这五县境内,其现存种群数量为１０００～１５００只;所有现存自然种群几乎均处在相互隔离的状态,群间已不可能进行基因交流,充分表明它们已到达灭绝边缘。然而其栖息地内的商业伐木规模仍在继续扩大,周围的人口压力正在不断增加,各猴群均面临不同程度的偷猎压力。这一现状委实令人担忧。如何拯救这一“国宝”应引起我国保护学家和各级政府有关职能部门的重视