On the possible role of nonreproductive traits for the evolution of unisexuality: Life‐history variation among males,females, and hermaphrodites in Opuntia robusta (Cactaceae)

In angiosperms, dioecy has arisen in 871–5,000 independent events, distributed in approximately 43% of the flowering families. The reproductive superiority of unisexuals has been the favorite explanation for the evolution of separate sexes. However, in several instances, the observed reproductive performance of unisexuals, if any, does not seem to compensate for the loss of one of the sex functions. The involvement of fitness components not directly associated with reproduction is a plausible hypothesis that has received little attention. Life‐history traits recently recognized as predictors of plant performance were compared among males, females, and hermaphrodites of a rare trioecious Opuntia robusta population in the field, using the cladode as the study unit. Cladode mortality by domestic herbivores was common and higher in females and hermaphrodites than in males. Males, females, or both displayed lower shrinkage and higher rates of survival, growth, and reproductive frequency than hermaphrodites. Unisexuals simultaneously outperformed hermaphrodites in demographic traits known to compete for common limiting resources, such as the acceleration of reproductive maturation (progenesis) and survival. A meta‐analysis combining the outcomes of each of the analyzed life‐history traits revealed a tendency of males (d₊₊ = 1.03) and females (d₊₊ = 0.93) to outperform hermaphrodites in presumably costly demographic options. Clonality is induced by human or domestic animal plant sectioning; and males and females highly exceeded hermaphrodites in their clonality potential by a factor of 8.3 and 5.3, respectively. The performances of unisexuals in the analyzed life‐history traits may enhance their reproductive potential in the long run and their clonality potential and could explain the observed increase of unisexuality in the population. Life‐history traits can be crucial for the evolution of unisexuality, but their impact appears to be habitat specific and may involve broad ontogenetic changes.     

Expressed Sequences from Conidial, Mycelial, and Sexual Stages ofNeurospora crassa

In theNeurosporaGenome Project at the University of New Mexico, expressed sequence tags (ESTs) corresponding to three stages of the life cycle of the filamentous fungusNeurospora crassaare being analyzed. The results of a pilot project to identify expressed genes and determine their patterns of expression are presented. 1,865 partial complementary DNA (cDNA) sequences for 1,409 clones were determined using single-pass sequencing. Contig analysis allowed the identification of 838 unique ESTs and 156 ESTs present in multiple cDNA clones. For about 34% of the sequences, highly or moderately significant matches to sequences (of known and unknown function) in the NCBI database were detected. Approximately 56% of the ESTs showed no similarity to previously identified genes. Among genes with assigned function, about 43.3% were involved in metabolism, 32.9% in protein synthesis and 8.4% in RNA synthesis. Fewer were involved in defense (6%), cell signalling (3.4%), cell structure (3.4%) and cell division (2.6%).     

IDENTIFICATION AND EXPRESSION ANALYSIS OF TWO 14‐3‐3 PROTEINS IN THE MOSQUITO Aedes aegypti,AN IMPORTANT ARBOVIRUSES VECTOR

The 14‐3‐3 proteins are evolutionarily conserved acidic proteins that form a family with several isoforms in many cell types of plants and animals. In invertebrates, including dipteran and lepidopteran insects, only two isoforms have been reported. 14‐3‐3 proteins are scaffold molecules that form homo‐ or heterodimeric complexes, acting as molecular adaptors mediating phosphorylation‐dependent interactions with signaling molecules involved in immunity, cell differentiation, cell cycle, proliferation, apoptosis, and cancer. Here, we describe the presence of two isoforms of 14‐3‐3 in the mosquito Aedes aegypti, the main vector of dengue, yellow fever, chikungunya, and zika viruses. Both isoforms have the conserved characteristics of the family: two protein signatures (PS1 and PS2), an annexin domain, three serine residues, targets for phosphorylation (positions 58, 184, and 233), necessary for their function, and nine alpha helix‐forming segments. By sequence alignment and phylogenetic analysis, we found that the molecules correspond to ? and ζ isoforms (Aeae14‐3‐3ε and Aeae14‐3‐3ζ). The messengers and protein products were present in all stages of the mosquito life cycle and all the tissues analyzed, with a small predominance of Aeae14‐3‐3ζ except in the midgut and ovaries of adult females. The 14‐3‐3 proteins in female midgut epithelial cells were located in the cytoplasm. Our results may provide insights to further investigate the functions of these proteins in mosquitoes.     

One- and two-electron oxidation of thiols: mechanisms,kinetics and biological fates

The oxidation of biothiols participates not only in the defense against oxidative damage but also in enzymatic catalytic mechanisms and signal transduction processes. Thiols are versatile reductants that react with oxidizing species by one- and two-electron mechanisms, leading to thiyl radicals and sulfenic acids, respectively. These intermediates, depending on the conditions, participate in further reactions that converge on different stable products. Through this review, we will describe the biologically relevant species that are able to perform these oxidations and we will analyze the mechanisms and kinetics of the one- and two-electron reactions. The processes undergone by typical low-molecular-weight thiols as well as the particularities of specific thiol proteins will be described, including the molecular determinants proposed to account for the extraordinary reactivities of peroxidatic thiols. Finally, the main fates of the thiyl radical and sulfenic acid intermediates will be summarized.     

Assessing the Greenhouse Gas Savings Potential of Extended Producer Responsibility for Mattresses and Boxsprings in the United States

Extended producer responsibility (EPR) legislation in the United States, which currently only exists on the state level, now includes three mattress EPR acts, which intend to shift the financial and operational burden of mattress end‐of‐life (EOL) management away from local and state government. It is important to keep in mind, however, that the original objective behind EPR is to reduce the environmental life cycle impacts of products. This article therefore quantifies the greenhouse gas (GHG) savings potential of mattress and boxspring recycling and reuse in the United States and also discusses labor implications and mattress design issues. We find that all three acts are unlikely to generate redesign incentives, but are expected to dramatically increase mattress collection and recycling. The collection and recycling of all 35 million EOL mattress and boxspring units estimated to reach the end of their lives in the United States every year would generate in the order of 10,000 jobs and GHG savings between 1 and 1.5 million metric tonnes.     

Sporostatic and Sporocidal Properties of Aqueous Formaldehyde

Aqueous formaldehyde is shown to exert both sporostatic and sporocidal effects on Bacillus subtilis spores. The sporostatic effect is a result of the reversible inhibition of spore germination occasioned by aqueous formaldehyde; the sporocidal effect is due to temperature-dependent inactivation of these spores in aqueous formaldehyde. The physicochemical state of formaldehyde in solution provides a framework with which to interpret both the sporostatic and sporocidal properties of aqueous formaldehyde.     

Cultured Human Tumour Cells May Be Arrested In All Stages of the Cycle During Stationary Phase: Demonstration of Quiescent Cells In G1, S and G2 Phase

Six human colon carcinoma cell lines were induced to enter stationary phase of growth by nutrient deprivation and cell crowding. Growth kinetics parameters (cell number, flow cytometric analysis of DNA distribution, and labelling and mitotic indices) were measured sequentially for all lines during the various stages of in vitro growth. Our results demonstrated that a substantial fraction of cells (9–18%) were located in G₂, phase when they changed from an exponential to a stationary mode of growth. Moreover, a large number of cells in stationary phase of growth had an S-phase DNA content, as determined by flow cytometry, but failed to incorporate radioactive DNA precursors (up to 15-fold difference). to substantiate these findings. cells in stationary phase of growth were induced to enter exponential growth by re-seeding in fresh medium at a lower density. Subsequently observed changes in DNA-compartment distribution, and in labelling and mitotic indices were those expected from cells that had been arrested at different stages of the cycle during their previous stationary phase. Thus, the non-proliferating quiescent state (Q), traditionally located ‘somewhere’ in G₁, phase, appears to be composed also of cells that can be arrested at other stages of the cycle (Q_s, and Q_G). Although the proportion of such cells is rather small, their contribution to the growth kinetics behaviour of human in vivo tumours will become apparent following ‘recruiting’ or ‘synchronizing’ clinical manoeuvres and will prevent the formation of a clear-cut wave of synchronized cells.     

Effects of ATP and NGF on Proliferation and Migration of Neural Precursor Cells

Neurochemical Research - Purinergic receptors belong to the most ancient neurotransmitter system. While their relevance in neurotransmission is well characterized, it has become clear that they...