Identification and comprehensive analysis of the CLV3/ESR‐related (CLE) gene family in Brassica napus L.

• The CLE (CLAVATA3/ESR) gene family, encoding a group of small secretory peptides, plays important roles in cell‐to‐cell communication, thereby controlling a broad spectrum of development processes. The CLE family has been systematically characterized in some plants, but not in Brassica napus.
• In the present study, 116 BnCLE genes were identified in the B. napus genome, including seven unannotated, six incorrectly predicted and five multi‐CLE domain‐encoding genes. These BnCLE members were separated into seven distinct groups based on phylogenetic analysis, which might facilitate the functional characterization of the peptides.
• Further characterization of CLE pre‐propeptides revealed 31 unique CLE peptides from 45 BnCLE genes, which may give rise to distinct roles of BnCLE and expansion of the gene family. The biological activity of these unique CLE dodecamer peptides was tested further through in vitro peptide assays. Variations in several important residues were identified as key contributors to the functional differentiation of BnCLE and expansion of the gene family in B. napus. Expression profile analysis helped to characterize possible functional redundancy and sub‐functionalization among the BnCLE members.
• This study presents a comprehensive overview of the CLE gene family in B. napus and provides a foundation for future evolutionary and functional studies.

     

Vegetation establishment in post-fire Adenostoma chaparral in relation to fine-scale pattern in fire intensity and soil nutrients

At fine spatial scales (0.1–10m), chaparral communities have been shown to be strongly influenced by canopy-gap patterns, leading to periodicities in vegetation at 4–5 m spatial scales. Fine-scale variations in fire behavior and post-fire erosion can lead to changes in the patterning of viable seeds and nutrients and may alter the spatial patterning of post-fire chaparral communities. This study deals with the relationship among fire behavior, post-fire nutrient availabilities and vegetation patterns in a 1-yr old, post-fire Adenostoma fasciculatum chaparral community in the Sierra Nevada Mountains, California, USA. Variations in mineral soil exchangeable cations (Ca, Mg) and extractable phosphorus (P0₄-P) were correlated with ash distribution. Cations and measures of ammonium and nitrate were also correlated with fire intensity, measured by the diameter of the smallest remaining A. fasciculatum twigs following fire. Fire intensity was correlated with the pattern of post-fire vegetation establishment based on first axis DC A scores. However, ash PO4-P was more highly correlated with sample DCA scores, local species richness and total cover (p < 0.01), suggesting that small-scale variations in PO4-P which correlate with ash distributions may be important in structuring this community. Two- and three-term local variance analysis revealed a maximum of pattern intensity in DCA first axis scores at 4–5 m intervals that likely corresponds to pre-fire canopy-gap patterns. However, total cover showed pattern at spatial scales of 8–10 m, and was correlated at this scale with patterns of ash distribution and fire intensity. Microtopographic patterns also occur at similar spatial scales. Microtopographic patterns appear important in determining post-fire plant nutrient and water distributions and, thereby, patterns of plant establishment. Thus, the scale and intensity of post-fire vegetation pattern may differ considerably from pre-fire conditions.     

The Regulation of Homopolar Doublets to Singlets in Glaucoma

ABSTRACT. In the ciliate Glaucoma scintillans , the process of transformation of unbalanced homopolar doublets to singlets was investigated. Cells were fixed 1–3 days after inoculation and impregnated with silver according to the Chatton-Lwoff technique. The two oral apparatuses (OAs) approached each other partly due to a loss of ciliary rows in one of the two components (semicells) consisting of a doublet. The contractile vacuole pore (CVP) in the narrow semicell (sc1) was lost at an early stage of regulation, while the position of CVP in the broad semicell (sc2) shifted toward the right after the loss of sc1. The sc1 of 20 row-intervals in breadth was a transition point above which the sc1 was able to persist for awhile, and beneath which it was actively lost. There was no evidence for an independent effect of sc2 on the transformation of doublets to singlets. In cell division, an additional reversed oral primordium (sOP) was formed in unbalanced doublets, usually within a narrow sc1 of 11–20 row-intervals. The position of the sOP was generally 4–6 row-intervals distant from the right side of the oral meridian (OM1) with the cell's left OA. Most of the doublets with an sOP lacked an oral primordium in the OM1. No mature triplet with 2 normal OAs and an abnormal OA was found in these preparations. The pathway of regulation, the movement of the CVP, and the formation of an sOP are discussed.     

Seasonal pattern of accumulation and effects of low temperatures on storage compounds in Trifolium repens

The seasonal pattern of concentrations of nitrogen, starch and vegetative storage protein (VSP) in stolons of Trifolium repens L. grown in the field were studied. Two different genotypes, cv. Aran and cv. Rivendel, differing in their morphology (stolon thickness and branching rate) but with similar growth rates, were used. Maximum concentrations of starch were found in summer whereas hydrolysis of starch took place throughout winter, suggesting that C storage is more important for winter survival than for promotion of early spring growth. On the other hand, VSP and nitrogen accumulated in autumn and early winter and then decreased when growth was resumed during early spring. For both cultivars, an inverse relationship was found between VSP concentration in stolons and mean air temperature, suggesting that VSP accumulation may be triggered by low temperature. Further experiments with plants grown under different regimes of temperature and daylength, suggested that VSP synthesis is stimulated by low root temperatures, with a slight synergistic effect of short daylength.
The effects of root temperature on growth, N₂ fixation, NH₄⁺ uptake and N allocation within Trifolium repens L., were studied under controlled conditions. The shoot growth rate was greatly reduced when root temperatures were lowered from 12 to 6°C, while the rate of stolon growth was less affected. Low root temperatures inhibited N2 fixation more than it did NH₄⁺ uptake, but the relative allocation of N to stolons was increased. Lowering root temperature also increased the accumulation of VSP in stolons. These results are discussed in terms of the mechanism associated with low temperature stimulation of VSP accumulation and its coupling with changes in the source/sink relations for allocation of N, between growth and storage.     

Heterodimerization is mainly responsible for the dominant negative activity of amino-terminally truncated rat androgen receptor forms

Rat androgen receptor (rAR) mutants devoid of the amino-terminal transactivation domain are able to behave as dominant negative regulators of wild-type rAR. To address the underlying mechanisms of the trans-dominant negative action, we have examined the roles of the DNA-binding domain (DBD) and the ligand-binding domain (LBD) in this process. Transactivation experiments in CV-1 cells complemented by electrophoretic mobility shift assays revealed that the dominant negative receptor forms repress the function of wild-type rAR mainly through heterodimer formation, rather than through competition for binding to cognate DNA elements. Heterodimerization of receptor forms containing LBDs may take place even in the absence of specific DNA binding.     

The common patterns of nature

We typically observe large‐scale outcomes that arise from the interactions of many hidden, small‐scale processes. Examples include age of disease onset, rates of amino acid substitutions and composition of ecological communities. The macroscopic patterns in each problem often vary around a characteristic shape that can be generated by neutral processes. A neutral generative model assumes that each microscopic process follows unbiased or random stochastic fluctuations: random connections of network nodes; amino acid substitutions with no effect on fitness; species that arise or disappear from communities randomly. These neutral generative models often match common patterns of nature. In this paper, I present the theoretical background by which we can understand why these neutral generative models are so successful. I show where the classic patterns come from, such as the Poisson pattern, the normal or Gaussian pattern and many others. Each classic pattern was often discovered by a simple neutral generative model. The neutral patterns share a special characteristic: they describe the patterns of nature that follow from simple constraints on information. For example, any aggregation of processes that preserves information only about the mean and variance attracts to the Gaussian pattern; any aggregation that preserves information only about the mean attracts to the exponential pattern; any aggregation that preserves information only about the geometric mean attracts to the power law pattern. I present a simple and consistent informational framework of the common patterns of nature based on the method of maximum entropy. This framework shows that each neutral generative model is a special case that helps to discover a particular set of informational constraints; those informational constraints define a much wider domain of non‐neutral generative processes that attract to the same neutral pattern.     

DNA replication cycle in parthenogenetically developing eggs of the starfish Asterina pectinifera

Starfish oocytes artificially activated by a calcium ionophore will develop normally if the formation of polar bodies is suppressed. In the present paper, schedules of the DNA replication period (S phase) of these parthenogenotes were explicitly timed using 5-bromo-2'-deoxyuridine (BrdU) and anti-BrdU monoclonal antibody. Their schedule of S phase was identical to that of fertilized eggs. Consequently, an S phase regulation system is triggered even in parthenogenotes raised by dual treatment of egg activation and polar body suppression. The S phase schedule of parthenogenotes confirms the temporal pattern of chromosome duplication, observed by other researchers, leading to tetraploid parthenogenotes. The S phase determination also provides a basis for argument concerning the number of centrioles participating in parthenogenetic development. If polar body formation of activated eggs was not suppressed, the first S phase was normal, but the second S phase did not recur on time. A rigidly regulated system of DNA replication cycle, which should be an essential prerequisite for parthenogenesis, thus requires the content of polar bodies.     

Spontaneous trait transference from dogs to owners

Abstract

This work found that participants attributed traits associated with breeds of dogs to their owners (indicating that a person may be perceived as more nervous if believed to own a Chihuahua, more heroic if believed to own a Collie, more aggressive if believed to own a Doberman, etc.). The findings further suggest that some people have folk theories that owners select breeds of dogs that resemble them dispositionally. When participants were unable to use this folk theory (when it was clear that the target people were not the dogs' owners and just randomly happened to share the same environment) those participants who owned dogs themselves still transferred traits; however those who did not own dogs themselves did not do so. These findings provide evidence of a novel associative effect in person impression and are discussed in terms of simple associative versus inferential processes.     

基于无人机影像的阿拉善东南部荒漠灌丛植被空间格局研究

干旱区灌丛植被空间格局受多种物理和生态过程影响，能够指示生态系统的状态。研究通过量化灌丛斑块大小的空间分布来评估阿拉善高原东南部覆沙荒漠植被生态系统的状态，采用点格局分析法分析灌木种群的相互关系，以阐明不同灌木种在斑块格局形成中的作用，并结合土壤条件及下垫面粗糙度等指标验证评估的准确性，探讨灌丛空间格局差异的内在机理。结果表明，研究区样方2灌丛斑块大小符合截尾幂律分布，其他样方符合对数正态分布，前者的空间结构及生境条件均优于后者，说明植被空间格局可以准确表征生态系统状态。在局地尺度上灌木种内和种间呈现不同的相互关系，以竞争关系为主导是导致斑块破碎化的主要驱动机制。小灌木（如猫头刺）的种内互利关系有利于促进多样化斑块形态的形成，而大灌木（如沙冬青和蒙古扁桃）种间的互利作用则有利于形成异质性更强的复杂空间格局。基于灌丛斑块的空间格局评估生态系统状态，可为保护和恢复生态脆弱区受损植被提供重要的借鉴。