The reactivity of neonatal rabbits to the mammary pheromone as a probe for viability

Newborn rabbits depend on a daily nursing interaction with the mother to gain milk and to survive. During this interaction, they localise and seize the nipples displaying a typical behaviour triggered by maternal odour cues. The mammary pheromone constitutes such a signal in domestic rabbits: it elicits sucking-related movements in more than 90% of the pups. However, some newborns remain unresponsive to the presentation of the pheromone, even pups apparently healthy and highly motivated to suck. The main goal of the present study was therefore to explore the link between the unresponsiveness of rabbit pups to the mammary pheromone and their growth and survival in breeding conditions. To that end, 293 newborns from 30 litters were tested for their head searching-oral grasping responses to the mammary pheromone on days 1 and 3, and their milk intake and mortality were followed up from days 1 to 21. It was hypothesised that unresponsive newborns would have subsequent difficulties in finding nipples, sucking and surviving. Early weight and success in milk intake were further considered as mediating factors in growth and viability. The results showed that pups that were unresponsive to the mammary pheromone on day 1 were less successful in gaining milk and had a higher rate of mortality than the responsive pups. However, this impact was modulated by the weight of pups: it appeared only in the lightest newborns. Moreover, this impact vanished on day 3. On the other hand, the pup weight and sucking success on days 1 to 3 strongly influenced viability and growth during the period extending from days 1 to 21. Taken together, the results show that the day-1 responsiveness of rabbit pups to the mammary pheromone can be considered as an indicator of individual viability in pups having a small weight (<48 g on day 1). The predictive validity of the pups’ pheromonal reactivity seems however time-limited as it works only during the first, but crucial, postnatal days.     

Development of the preprophase band from random cytoplasmic microtubules in guard mother cells of Allium cepa L.

The organization of microtubule (MT) arrays in the guard mother cells (GMCs) of A. cepa was examined, focussing on the stage at which a longitudinal preprophase band (PPB) is established perpendicular to all other division planes in the epidermis. In the majority of young GMCs, including those seen just after asymmetric division, MTs are distributed randomly throughout the cortex and inner regions of the cytoplasm. Few MTs are associated with the nuclear surface. As the GMCs continue to develop, MTs cluster around the nucleus and a PPB appears as a wide longitudinal band. Microtubules also become prominent between the nucleus and the periclinal and transverse walls, while they decrease in number along the radial longitudinal walls. The PPB progressively narrows by early prophase, and a transversely oriented spindle gradually ensheaths the nucleus. These observations indicate that the initial, broad PPB is organized by a rearrangement of the random cytoplasmic array of MTs. Additional reorganization is responsible for MTs linking the nucleus and the cortex in the future plane of the cell plate, and for narrowing of the PPB.Abbreviations GMC guard mother cell - MT microtubule - PPB preprophase band     

Paradise lost: Mitochondrial eve refuted

Being based solely on neontological data, all «unique parent» evolutionary hypotheses, of which «Mitochondrial Eve» is one, fall into the category ofscala naturae. Mathematical treatment of neontological data bases, using cladistic approaches does not confer the status of scientific hypotheses onto such scenarios. Apart from these fundamental problems, such hypotheses are flawed on a number of other bases, including the fact that there is a proportion of parental contribution to mitochondrial lineages, despite widely publicised statements that mithocondrial DNA in mammals is «strictly» maternally inherited. Other weaknesses of «unique mother» hypotheses on that their proponents endeavour to describe the evolution of diploid organisms on the basis of variability in extant haploid organelles, the evolution of which is delinked from that of the diploid organism. A further difficulty is that it is not possible to reconstruct interspecific relationships on the basis of intraspecific variability. There is a general ignorance among proponents of «unique mother» hypotheses regarding the distribution of biological variability on the surface of the globe, a fact which renders the molecular clock inaccurate, and which upsets the simplistic proposal that molecular diversity equates with time. «Unique mother» scenarios are also invalidated by the presence of shared chromosome and other polymorphisms in african great apes and humans at similar percentages in the different lineages, a fact which indicates that these evolving populations did not experience «bottlenecks». These and other difficulties effectively refute the «Mitochondrial Eve» hypothesis, which in any case much resembles creationism of a special kind, in which the offspring of a breeding pair are visualised as belonging to a species different from its parents. Such extreme examples of the punctuational mode of evolution are highly likely to be incorrect.     

百合花粉母细胞间细胞融合期间腺苷三磷酸酶活性的细胞化学定位及其与染色质胞间转移的关系

用标准的磷酸铅沉淀的细胞化学方法,对百合花粉母细胞间染色质穿壁运动期间及其前后三个时期中的腺苷三磷酸酶(ATP 酶)活性进行了超微结构的定位。结果表明:(1)在穿壁前,ATP 酶活性主要定位于质膜、胞间连丝及细胞间隙;在内质网、高尔基体、质体和某些局部的基质(groundplasm)中,也表现有 ATP 酶活性反应的产物;但在染色质和核仁中,一般都没有这种反应。(2)在穿壁时,染色质从一个细胞穿壁转移到另一个相邻细胞,同时看到染色质和核仁内出现密集的 ATP 酶活性反应产物;在内质网和高尔基体的腔内以及质体的片层上也产生明显的 ATP 酶活性反应;而在质膜、胞间连丝及细胞间隙内 ATP 酶活性明显降低,甚至看不到明显的活性反应。(3)在穿壁后,质膜及细胞间隙中又产生明显的 ATP 酶活性反应产物,但核内染色质上的 ATP 酶活性则显著降低,而核仁内则仍有较高的活性。同前二个时期一样,内质网、高尔基体和质体上的 ATP 酶仍表现明显的活性反应。最后讨论了三个不同发育时期 ATP 酶活性及其分布部位的改变与染色质胞间转移的关系。     

空间条件对几种粮食作物的同工酶和细胞学特性的影响

搭载１９８７年发射的两颗返地卫星（８月５—１０日和９月９—１７日）的几种小麦、大麦种子,经回收后初步研究表明：（１）对发芽率的影响：空间处理的种子,其发芽率与对照无差别;（２）对茎及生育期的影响：空间处理的种子长成的幼苗比对照强壮,植株高度有些品种明显的矮于对照。生育期有不同程度延长;（３）对染色体结构的影响：花粉母细胞减数分裂观察表明搭载卫星的种子当代可诱导出比地面更多的染色体桥、落后染色体及染色体数目异于正常体细胞数目的现象。小麦品种Ｃｏｃｏｒｉｔ—７１经空间处理后花粉母细胞的染色体数目异常可高达２０．５１％,而地面对照组其花粉母细胞基本正常（２ｎ＝２８）;（４）对同工酶的影响：经空间处理的小麦种子酯酶、过氧化物酶的同工酶谱带空间处理的比地面对照减少。由此可见,空间处理可诱导纯合植物种子发生变异,为农作物育种创造一个新途径。     

Experimental studies on the function of the cortical cytoplasmic zone of the preprophase microtubule band

Summary Centrifugation of young seedlings ofTriticum durum andTriticum aestivum for 8–10 hours at 1,500–2,000 x g causes a serious disorder of the spatial organelle relationships in the interphase as well as the preprophase and mitotic subsidiary cell mother cells (SMCs). The nucleus, most organelles and cytoplasm are displaced to the centrifugal end of the cell, while the vacuoles lie at the other end. However, after centrifugation, the preprophase microtubule bands (PMBs) are nucleated and remain at the expected position close to the guard cell mother cells (GMCs). In some elongated SMCs the PMBs become completely separated from the nucleus. The mitotic spindle exhibits variable orientation and is usually formed at some distance from the PMB cortical zone.Cytokinesis in SMCs is spatially highly disturbed and the cell plate shows a variety of unpredictable dispositions, which seem to be determined by: 1. the position of the preprophase-prophase nucleus and the orientation of the mitotic spindle as well as their spatial relationships to the PMB cortical zone, and 2. the space available for cell plate growth. Many of the daughter cells exhibit a highly variable shape and size in different planes. Usually one edge of the cell plate partly or totally joins the anticlinal parent wall adjacent to the PMB cortical zone.In some SMCs ofZea mays andTriticum aestivum, the junction regions of the periclinal walls with the anticlinal ones, lined by the PMB cortical zone in normal SMCs, are detectably thickened after the arrest of mitosis and the prevention of interphase microtubule formation by a prolonged colchicine treatment. In a small number of protodermal cells of the same plants, participating in the development of stomatal complexes, irregular wall bodies or incomplete wall sheets were formed at wall regions lined by the PMB cortical zone.The presented observations are in line with the following hypotheses: 1. the PMB cortical zone interacts with the growing edges of the cell plate attracting it to fuse with the underlying parent wall when the latter approaches the former at a critical distance, and 2. in SMCs particular regions of the PMB cortical zone and/or the adjacent plasmalemma promote the local wall deposition in the absence of microtubules.     

Alteration of division polarity and preprophase band orientation in stomatogenesis by light

We have developed an experimental system in which the irradiation with a red light pulse induces stomatal disorientation in the hypocotyl epidermis ofCucumis sativus L. In this system, the orientation of the division plane in guard mother cells was not defined correctly. Preprophase bands formed in these cells but their orientation was abnormal.     

卷丹小孢子母细胞减数分裂染色体行为的研究

对引种于陕西汉中地区的三倍体卷丹的小孢子母细胞减数分裂进程、花粉生活力和可育性进行了分析。结果显示:减数分裂时期与花蕾、花药长度及花药壁颜色呈现出一定的相关性,处于减数分裂时期的卷丹花蕾长度在2.5～3.2 cm之间,花药长度在1.4～1.8 cm之间;从细线期到成熟花粉粒,花药壁的颜色呈现出淡绿色-淡黄绿色-黄绿色-橘黄色的变化趋势,花药内容物颜色也从透明逐渐变为粘稠的橘红色。减数分裂终变期染色体构型以三价体为主,平均构型为:11.6Ⅲ+2Ⅱ+1.1Ⅰ,可判断该种源地卷丹为同源三倍体。减数分裂中出现染色体不均等分裂、染色体落后、染色体桥及微核现象,同时观察到成熟花粉粒大小差异较大,极轴与赤道轴乘积在839.465～3327.907μm2范围内,趋于正态分布,为三倍体卷丹花粉的高度不育提供了细胞学证据。以卷丹为母本与大花卷丹进行杂交,得到一定数量的种子,其中有胚率达到了43.0%,成苗率为67.4%,说明三倍体卷丹在百合育种中具有一定的价值。     

Reducing infectivity of HIV upon exposure to surfaces coated with N,N‐dodecyl,methyl‐polyethylenimine

The infectivity of high‐titer, cell‐free HIV in culture media and human milk is rapidly reduced upon exposure to polyethylene slides painted with the linear hydrophobic polycation N,N‐dodecyl,methyl‐polyethylenimine (DMPEI). Accompanying viral p24 protein and free viral RNA analysis of solutions exposed to DMPEI‐coated surfaces suggests that virion attachment to the polycationic surface and its subsequent inactivation are the likely mechanism of this phenomenon. Biotechnol. Bioeng. 2013; 110: 2058–2062. © 2013 Wiley Periodicals, Inc.