Structural, histochemical, and protein analysis of male reproductive development in willow

Information on the development of the male reproductive structures in willow will help advance our understanding of its reproductive behavior and contribute to our ability to work towards its improvement. Willow also offers the opportunity to study male sterility, a subject matter which is not typically dealt with in woody plants. As compared to the three willow species examined (Salix eriocephala, S. exigua, and S. purpurea), pollen development in S. discolor S365 showed several abnormalities starting with the delay in meiosis. This lasted for about 10 days and meiosis eventually occurred as manifested by the formation of microspores. However, most of the resulting microspores collapsed, while only a few developed into pollen grains. The large number of undeveloped and disintegrated microspores appeared to make the few pollen grains sticky, preventing them from being dispersed. Histochemical analysis showed that meiosis in most species of willow was associated with the presence of large amounts of insoluble polysaccharides in the anther wall layers, but only very few of these were observed in S. discolor. Also, a 32-kDa protein which is the most abundant protein in the reproductive structures of willow, was absent in S. discolor S365. Proteomic analysis showed that this is similar to the storage proteins in Populus x canadensis and P. deltoides. Therefore, male sterility in S. discolor may be due to some genetic defects affecting the accumulation of essential reserves in its reproductive structures. The mechanism behind this is unknown, but this study has established the nature of sterility in S. discolor S365.     

Balanced complex chromosomal rearrangements (BCCR) with at least three chromosomes and three or more breakpoints: report of three new cases

Balanced complex chromosomal rearrangements (BCCR) encompass a heterogeneous group of rare chromosomal aberrations. In this paper, we report three cases of BCCRs. In two the probands were referred for either genetic counseling or prenatal management. One case was ascertained after chromosome analysis performed because of psychiatric manifestations; this was an isolated finding. We also outline the molecular cytogenetic techniques, which were essential in confirming and precisely delineating the BCCRs identified in these patients. In addition the various aspects of genetic counseling for this type of chromosomal rearrangement, highlighting the details particular to each individual case are discussed. We discuss the classification for this type of chromosomal mutation.     

Trigger factor-assisted folding of bovine carbonic anhydrase II

Spontaneous refolding of GdnHCl denatured bovine carbonic anhydrase II (BCA II) shows at least three phases: a burst phase, a fast phase, and a slow phase. The fast and slow phases are both controlled by proline isomerization. However, we find that in trigger factor (TF)-assisted BCA II folding, only the fast phase is catalyzed by wild-type TF, suggesting that certain proline residues are accessible in folding intermediates. The refolding yields of BCA II assisted by wild-type TF and TF mutants which lack PPIase activity are about the same, which provides further experimental evidence that the PPIase and chaperone activities of TF are independent. The binding of TF to folding intermediates during BCA II refolding was characterized by chemical crosslinking and Western blotting. A scheme for TF-assisted BCA II folding is proposed and the possible role of the TF dimer as a "binding" chaperone in vivo is discussed.     

Female eviction, abortion, and infanticide in banded mongooses (Mungos mungo): implications for social control of reproduction and synchronized parturition

Most cooperatively breeding species exhibit high reproductiveskew, where reproduction within the social group is monopolizedby a dominant pair. In many of these species, social controlof reproduction is the mechanism driving reproductive skew:individuals within the social group actively reduce the reproductivesuccess of others. In species where females do not suppressconception in other females, alternative routes to skewing thesocial group's reproductive output include inducing abortionin rivals, evicting them, or killing their young. This studyexamines instances of female eviction, abortion, and infanticidein a cooperatively breeding species with low preparturitionreproductive skew, the banded mongoose (Mungos mungo). Althoughinstances of these behaviors are rare in this species, aspectsof their occurrence have implications for social control ofreproduction. Abortion can be induced by the stress of beingevicted. The readmittance of females that abort suggests thatreducing communal litter size is a possible selective pressurefor eviction. This is supported by the occurrence of evictionevents in groups with relatively high numbers of reproductivefemales and by the eviction of young reproductive females. Thetiming of abortion events suggests that synchronization of parturitionwith other females in the group is a major selective pressure.Infanticide could represent the selective pressure for synchronizedparturition. Alternatively, synchronization may minimize competitiveasymmetry between pups born to different females. This paperalso describes incidences where a female aborts or gives birthto her litter over different days in order to synchronize parturition:behavior previously unrecorded in mammals.     

夜间温度升高对双季早晚稻产量的影响

温度是影响水稻生长发育的重要因素,但夜间温度升高对双季水稻产量的影响还不清楚。利用两间玻璃室内夜间不同的温度条件,研究了水稻生长期间夜温升高对双季早、晚稻产量的影响。结果表明,夜间最低温度每升高1℃早稻产量降低5.42%-9.48%,而夜间最低温度每升高1℃晚稻产量提高8.99%-11.28%。夜温升高有利于早、晚稻的分蘖,增加有效穗数,但不利于颖花分化,使每穗粒数减少;夜温升高使早稻结实率下降,但提高晚稻的结实率。     

21例人流术后节育器嵌顿致滞留或残留于宫内取出的临床分析

目的探讨带器妊娠行人工流产术后节育器嵌顿致滞留或残留于宫内患者取出节育器的效果。方法回顾性分析2006年2月～2009年12月期间在永康市计划生育指导站21例患者的临床资料。结果21例在B超引导下,均成功取出。结论对放置IUD的妇女要定期复查,对放置IUD避孕失败的妇女,明确宫腔内是否有IUD,做到早发现,早诊断,及时正确地处理。     

Concomitant polymorphism: Crystallising dichloro-bis(2,4-lutidine)-zinc as both chiral and racemic phases

The crystallisation of dichloro-bis(2,4-lutidine)-zinc from various solvents (e.g. ethanol, THF and 2,4-lutidine) has been investigated and two phases were isolated. The structures of both phases were determined by single crystal X-ray diffraction and both types of crystals were found to be composed of conformationally chiral molecules. One phase (α-1) is racemic and crystallises in space group P2₁/c, while the other phase (β-1) crystallises in the enantiomorphous space group P4₁2₁2 with a low Flack parameter. In a few cases the chiral and racemic phases crystallised concomitantly; this phenomenon is rare and can be useful in the development of tools for the prediction of crystal structures.     

Symmetry breaking and convergent extension in early chordate development

The initiation of axis, polarity, cell differentiation, and gastrulation in the very early chordate development is due to the breaking of radial symmetry. It is believed that this occurs by an external signal. We suggest instead spontaneous symmetry breaking through the agency of the Turing-Child field. Increased size or decreased diffusivity, both brought about by mitotic activity, cause the spontaneous loss of stability of the homogeneous state and the evolution of the metabolic pattern during development. The polar metabolic pattern is the cause of polar gene expression, polar morphogenesis (gastrulation), and polar mitotic activity. The Turing-Child theory explains not only the spontaneous formation of the invagination in gastrulation but also the coherent cell movement observed in convergence and extension during gastrulation and neurulation. The theory is demonstrated with respect to experimental observations on the early development of fish, amphibian, and the chick. The theory can explain a multitude of experimental details. For example, it explains the splayed polar progression of reduction in the fish blastoderm. Reduction starts on that side of the blastoderm margin, which will initiate invagination several hours later. It progresses toward the blastoderm center and somewhat laterally from this future "dorsal lip". This is precisely as predicted by a Turing-Child system in a circle. And for a fish like zebrafish with a blastoderm that is slightly oval, reduction is observed to progress along the long axis of the ellipse, which is what Turing-Child theory predicts. In general the shape and the chemical nature of the experimental patterns are the same as predicted by the Turing couple (cAMP, ATP). Embryological polarity and convergent extension are based on polar eigenfunction and saddle-shaped eigenfunction, respectively.     

Cytological mechanism of pollen abortion resulting from allelic interaction of F1 pollen sterility locus in rice (Oryza sativa L.)

Pollen abortion is one of the major reasons causing the inter-subspecific F₁ hybrid sterility in rice and is due to allelic interaction of F₁ pollen sterility genes. The microsporogenesis and microgametogenesis of Taichung 65 and its three F₁ hybrids were comparatively studied by using techniques of differential interference contrast microscopy, semi-thin section light microscopy, epifluorescence microscopy and TEM. The results showed that there were differences among the cytological mechanisms of pollen abortion due to allelic interaction at the three F₁ pollen sterility loci. The allelic interaction at S-a locus resulted in microspores unable to extend the protoplasm membrane with the enlargement of the microspore at the middle microspore stage and finally producing empty abortive pollen. The allelic interaction at S-b locus caused asynchronous development of microspores at the middle microspore stage producing stainable abortive pollen. The allelic interaction at S-c locus mainly led to the non-dissolution of the generative cell wall and finally caused the hybrid F₁ mainly producing stainable abortive pollen. Genotypic identification indicated that the abortive pollen were those with S ^j allele.     

Evaluation of the hemoglobin-binding activity of Actinobacillus pleuropneumoniae using fluorescein-labeled pig hemoglobin and flow cytometry

In the present study, the hemoglobin (Hb)-binding activity of Actinobacillus pleuropneumoniae was examined using fluorescein-labeled pig Hb and flow cytometry. Comparison of the Hb-binding activity of A. pleuropneumoniae serotype 1 strain 4074 grown under iron-restricted conditions with cells grown under iron-sufficient conditions indicated that iron-restriction in A. pleuropneumoniae promotes the expression of Hb receptors, and that Hb-binding activity is, at least in part, iron-repressible. Hb-binding activity was also observed in representative strains of A. pleuropneumoniae belonging to serotypes 1 and 2. In addition, A. pleuropneumoniae serotype 1 LPS or capsule isogenic mutants were tested in flow cytometry in order to understand the influence of surface polysaccharides on Hb-binding activity. Experiments with an acapsulated mutant indicated that surface molecules with Hb-binding activity are more exposed at the cell surface in the absence of capsular polysaccharides. However, the Hb-binding activity of LPS mutants analyzed in this study was unchanged compared to the parent strain. The outer membrane proteins profile of A. pleuropneumoniae serotype 1 grown under iron-restricted or iron-sufficient conditions was also evaluated by polyacrylamide gel electrophoresis. Iron-regulated outer membrane proteins were observed under iron-restricted growth conditions which suggests that one or more of these outer membrane proteins may play a role in the Hb-binding activity detected by flow cytometry.