Accounting for biological variation in differential display two-dimensional electrophoresis experiments

Variation of protein expression levels was investigated in the heart, lung and liver from an inbred (C57/BL6) and an outbred (CD-1) mouse line. Based on the measured inter-individual variation, optimal sample sizes for two-dimensional electrophoresis experiments were determined by means of power analysis. For both lines, the level of protein expression variation was in the range of technical variation. Thus, although the differences in protein expression variation were significant between organs and mouse lines, optimal sample sizes were very similar (between 8 for heart proteins from C57/BL6 and 10 for liver proteins of the same line). Proteins with organ expression bias (higher expression in one organ as compared to the other two organs) exhibited higher variation of expression and the proportion of these proteins in each organ explained at least partly inter-organ differences in protein expression variation. The results suggest that proteomic experiments using more heterogeneous mouse samples would not require much larger sample sizes than those using narrowly standardized samples. Experiment designs encompassing a broader genetic variation and thus affording increased relevance of the results can be accessible to proteomics researchers at still affordable sample sizes.     

The aged microenvironment contributes to the age-related functional defects of CD4 T cells in mice

CD4 T cells, and especially T follicular helper cells, are critical for the generation of a robust humoral response to an infection or vaccination. Importantly, immunosenescence affects CD4 T‐cell function, and the accumulation of intrinsic defects decreases the cognate helper functions of these cells. However, much less is known about the contribution of the aged microenvironment to this impaired CD4 T‐cell response. In this study, we have employed a preclinical model to determine whether the aged environment contributes to the defects in CD4 T‐cell functions with aging. Using an adoptive transfer model in mice, we demonstrate for the first time that the aged microenvironment negatively impacts at least three steps of the CD4 T‐cell response to antigenic stimulation. First, the recruitment of CD4 T cells to the spleen is reduced in aged compared to young hosts, which correlates with dysregulated chemokine expression in the aged organ. Second, the priming of CD4 T cells by DCs is reduced in aged compared to young mice. Finally, naïve CD4 T cells show a reduced transition to a T follicular helper cell phenotype in the aged environment, which impairs the subsequent generation of germinal centers. These studies have provided new insights into how aging impacts the immune system and how these changes influence the development of immunity to infections or vaccinations.     

Stink bug interaction with host plants during communication

In solitary plant-dwelling stink bug species, success depends crucially on efficient mate location and recognition, mediated by signals transmitted through the plant. All stink bugs investigated so far communicate with species and sex-specific narrow-band calling and courtship song signals produced by abdomen vibration. Calling songs of lower specificity are characterized by readily repeated units emitted with regular repetition rate from the same place on a plant, while courtship songs take place at shorter distances in the process of species and sex recognition, together with signals of other modalities. Signal spectra with about 100Hz fundamental frequency and harmonics below 1000Hz are tuned to the resonant properties of their green host plants. The majority of the identified leg vibratory receptor cells and the underlying ventral cord interneurons respond best in the frequency range below 500Hz. Green plants with low pass filtering properties transmit optimally signals with a dominant frequency around 100Hz and strongly attenuate vibrations above 600Hz. Accurate tuning of signal spectral properties with the plant's mechanical characteristics enables communication over several meter distances, with dispersive bending waves running through the plant's rod-like structures under standing wave conditions.     

First report of antennular attachment organs in a barnacle nauplius larva

Larvae released from Newmaniverruca albatrossiana were cultured in the laboratory until the cypris stage. The brood size of individuals was low, about 60 larvae per brood. The exact number of instars was not determined. Early instars had the morphology normally seen in lecithotrophic nauplii of thoracican cirripedes. They had uniramous antennules with a few apical setae and biramous antennae and mandibles equipped with natatory setae only. Neither antennae nor mandibles carried any enditic spines or setae and the mouth cone was diminutive. The last nauplius stage obtained in our cultures was typical except in the structure of antennules. The head shield was enlarged but not flexed down, the antennae and mandibles were virtually unchanged from earlier instars, and the ventral thoracic process was well developed but without any external appendages. In contrast, the antennules had the complex shape and segmentation otherwise seen only in cypris larvae, where they are used for bipedal walking on the substratum in search of a settlement site. The similarity included the specialized shape of the first two antennular segments and the specialization of the third as an attachment organ. Nauplii just prior to this last instar had simple, straight antennules but completely lacked setae and instead terminated bluntly in what appears to be an incipient attachment organ. The presence of cypris-like antennules in late nauplii has not previously been recorded in cirripedes. We suggest that this will allow the larvae to attach on the substratum temporarily before they reach the cypris instar and this will increase the chance of settling successfully on their rare substratum (sea urchin spines). The specialization in late N. albatrossiana nauplii will therefore decrease mortality during the larval phase and thus counterbalance the very low breeding potential in this deep-sea species.     

扁绒泡菌Physarum compressum原质团细胞核核骨架制备技术的研究

以扁绒泡菌显型原质团为材料,进行细胞核的提纯、核骨架的制备及电镜观察。结果表明：用2mol/L NaCl+TritonX-100/NP40可得到具有复合纤维的核骨架,而用Lis + TritonX-100/NP40得到的核骨架具有核纤层,不使用RNase得到了具有网状的细胞核骨架,RNA在核骨架的结构形态中起重要作用。阐述了原质团中游离细胞核在细胞生物学研究中的意义。     

一种快速的胚胎组织总RNA的提取方法

简要介绍一种改进的提取人体器官组织总RNA的方法,该方法具有费用低,快速简便,重复性好的优点,提取的RNA无DNA等污染物,完全能满足基因表达研究的需要。     

On the evolution of clonal plant life histories

Clonal plant life histories are special in at least four respects: (1) Clonal plants can also reproduce vegetatively, (2) vegetative reproduction can be realised with short or long spacers, (3) and it may allow to plastically place vegetative offspring in benign patches. (4) Moreover, ramets of clonal plants may remain physically and physiologically integrated. Because of the apparent utility of such traits and because ecological patterns of distribution of clonal and non-clonal plants differ, adaptation is a tempting explanation of observed clonal life-history variation. However, adaptive evolution requires (1) heritable genetic variation and (2) a trait effect on fitness, and (3) it may be constrained if other evolutionary forces are overriding selection or by constraints, costs and trade-offs. (1) The few studies undertaken so far reported broad-sense heritability for clonal traits. Variation in selectively neutral genetic markers appears as pronounced in populations of clonal as non-clonal plants. However, neutral markers may not reflect heritable variation of life-history traits. Moreover, clonal plants may have been sampled at larger spatial scales. Empirical information on the contribution of somatic mutations to heritable variation is lacking. (2) Clonal life-history traits were found to affect fitness. However, much of this evidence stems from artificial rather than natural environments. (3) The relative importance of gene flow, inbreeding, and genetic drift, compared with selection, in the evolution of clonal life histories is hardly explored. Benefits of clonal life-history traits were frequently studied and found. However, there is also evidence for constraints, trade-offs, and costs. In conclusion, though it is very likely, that clonal life-history traits are adaptive, it is neither clear to which degree this is the case, nor which clonal life-history traits constitute adaptations to which environmental factors. Moreover, evolutionary interactions among clonal life-history traits and between clonal and non-clonal ones, such as the mating system, are not well explored. There remains much interesting work to be done in this field – which will be particularly interesting if it is done in the field.     

Ultrastructural studies of dorsal ciliated organs in Spionidae (Annelida: Polychaeta)

The distribution and structural components of dorsal ciliated organs (dco) in 15 species of the Spionidae were studied by scanning- and transmission electron microscopy. Based on the distribution patterns of dco, the investigated species are divided into four non-systematic groups: (I) paired anterior dco, (II) paired dco extending posteriorly for several chaetigers, (III) paired anterior dco in combination with unpaired, sexually dimorphic, metameric dco, and (IV) paired anterior dco in combination with paired, metameric dco. Previous ultrastructural studies have only included species possessing organs of groups I and III. In the present investigation the ultrastructure of dco found in Laonice bahusiensis and Spio cf. filicornis (species with dco of groups II and IV) is studied in an attempt to consider their homology. Apart from the metameric dco of group III, similarities of the cellular components of the dco indicate a homology to nuchal organs.     

Optimal allocation to vegetative and sexual reproduction in plants: the effect of ramet density

Vegetative reproduction is a very common alternative by which plants can contribute to the next generations. There are many considerations predicting which mode of reproduction, vegetative or sexual, should be favored and numerous experimental studies to verify them. However, the results are inconsistent especially when the effect of plant density is considered. I apply here a dynamic optimization model to predict the rate of vegetative and sexual reproduction in plants as a response to changes in the local plant density. The population is assumed to occupy a heterogeneous environment consisting of patches in which growth and reproduction of plants are possible and unfavorable space between them. As the environment is globally stable, the seeds, which can disperse without restriction, exhibit a constant recruitment rate. The ramets are assumed to settle only within the patch of the mother plant. The rate of ramet production effects local density, which in turn determines ramet recruitment. The optimal strategy maximizes the expected lifetime genetic contribution, realized via both vegetative and sexual reproduction. The solutions obtained under these assumptions are dualistic. The model predicts that different approaches applied in studying the effect of ramet density should give opposite outcomes. When the comparison is between patches in natural populations, a positive relationship between relative ramet allocation and density is expected. When the density is experimentally manipulated or its effect is analyzed across different successional stages, a negative relationship should be found. The results seem to be confirmed by empirical studies.