Phylogenetic relationships between the chlorophyll a/b binding protein (CAB) multigene family: An intra- and interspecies study

Summary The genome ofGlycine max (L.) Merr. cv. Dare contains a chlorophyll a/b binding (Cab) protein gene family consisting of 10 genes. The primary structures of two linkedCab genes (Cab 4 andCab 5) were determined. A comparison of the nucleic acid and predicted amino acid sequences ofCab 4 andCab 5 revealed a high degree of similarity (96% and 98%, respectively). Phylogenetic inferences drawn from sequence comparisons between previously characterized soybeanCab 1, 2, and 3 andCab 4 and 5 suggested that soybeanCab 3 was an evolutionarily distant member within this family. We further investigated the molecular evolution of theCab gene family by comparing nucleotide sequences from 25 differentCab genes representing diverse phylogenetic taxa including moncot and dicot species. Phylogenetic inferences from these data support existing morphological phylogenies in that all species within one family clustered together. These data suggested that the Solanaceae were more evolutionarily distant from the monocots than the Fabaceae and Brassicaceae. In addition, these data supported the theory thatCab Type I and II genes originated prior to divergence of the monocots and dicots.     

Helical Carbon Nanotubes Enhance the Early Immune Response and Inhibit Macrophage-Mediated Phagocytosis of Pseudomonas aeruginosa

Aerosolized or aspirated manufactured carbon nanotubes have been shown to be cytotoxic, cause pulmonary lesions, and demonstrate immunomodulatory properties. CD-1 mice were used to assess pulmonary toxicity of helical carbon nanotubes (HCNTs) and alterations of the immune response to subsequent infection by Pseudomonas aeruginosa in mice. HCNTs provoked a mild inflammatory response following either a single exposure or 2X/week for three weeks (multiple exposures) but were not significantly toxic. Administering HCNTs 2X/week for three weeks resulted in pulmonary lesions including granulomas and goblet cell hyperplasia. Mice exposed to HCNTs and subsequently infected by P. aeruginosa demonstrated an enhanced inflammatory response to P. aeruginosa and phagocytosis by alveolar macrophages was inhibited. However, clearance of P. aeruginosa was not affected. HCNT exposed mice depleted of neutrophils were more effective in clearing P. aeruginosa compared to neutrophil-depleted control mice, accompanied by an influx of macrophages. Depletion of systemic macrophages resulted in slightly inhibited bacterial clearance by HCNT treated mice. Our data indicate that pulmonary exposure to HCNTs results in lesions similar to those caused by other nanotubes and pre-exposure to HCNTs inhibit alveolar macrophage phagocytosis of P. aeruginosa. However, clearance was not affected as exposure to HCNTs primed the immune system for an enhanced inflammatory response to pulmonary infection consisting of an influx of neutrophils and macrophages.     

Posttranslationally modified tubulins and microtubule organization in hemocytes of the brine shrimp, Artemia franciscana

Crustaceans possess blood cells (hemocytes) that mediate organismal defense and are analogous to vertebrate leukocytes. In order to more fully characterize these types of cells, hemocytes of the branchiopod crustacean, Artemia franciscana, were analyzed. The data indicate that Artemia have one type of hemocyte, ranging in morphology from compact and spherical to flat and spreading when examined in vitro. Electron microscopy revealed many cytoplasmic granules in the hemocytes and only a limited number of other membrane-bound organelles. Centrioles and microtubules were also visible in thin sections of chemically fixed samples. The cytoplasm of spherical hemocytes was completely labeled by general antitubulin antibodies, but in flattened hemocytes packing of cytoskeletal elements was less tight and individual microtubules were observed. Probing of Western blots disclosed acetylated, tyrosinated, and detyrosinated tubulin isoforms in hemocyte homogenates, the first characterization of posttranslationally modified tubulins in this cell type. Acetylated tubulin was restricted to a subset of microtubules, whereas tyrosinated microtubules were displayed more abundantly. Staining obtained with antibody to detyrosinated tubulin was unusual because it was limited to the perinuclear region of hemocytes. Incubation of blood cells with a monoclonal antibody to gamma-tubulin yielded fluorescent dots sometimes in pairs, a pattern characteristic of centrosomes. The findings support the conclusion that Artemia hemocytes undergo rapid morphogenesis in vitro accompanied by extensive rearrangement of their microtubules, the latter probably indicative of cytoskeletal changes that occur during cell movement and phagocytosis. Additionally, the hemocytes contain posttranslationally modified alpha-tubulins and centrosome-associated gamma-tubulin, both with the potential to influence microtubule organization and function.     

Effects of 1α,25-,24R,25-, and 1α,24R,25-hydroxylated metabolites of vitamin D3on calcium and phosphate absorption by duodenum from intact and nephrectomized rats

The effects of 1α,25-dihydroxyvitamin D₃, 24R,25-dihydroxyvitamin D₃ and 1α,24R,25-trihydroxyvitamin D₃ on active calcium and phosphate transport by rat duodenum were studied in vitamin D-deficient rats that either underwent sham surgery or were bilaterally nephrectomized. Both 1α, 25-dihydroxy- and 1α,24R,25-trihydroxyvitamin D₃ markedly stimulated calcium and phosphate absorption with similar effects in shamoperated and nephrectomized rats. A 10-fold higher dose of 24R,25-dihydroxyvitamin D₃ was required for an equivalent stimulation of absorption in sham-operated rats, and this compound had no effect on duodena from nephrectomized rats. These data provide the first evidence that 24R,25-dihydroxy- and 1α,24R,25-trihydroxyvitamin D₃ can stimulate the active intestinal absorption of phosphate. The lack of response to 24R,25-dihydroxyvitamin D₃ in nephrectomized rats confirms prior results which indicated that renal metabolism of this secosteroid to 1α,24,25-trihydroxyvitamin D₃ is required for biological activity. In addition, we describe a simple bioassay technique which apparently reflects, with reasonable accuracy, the changes in duodenal calcium and phosphate absorption which occur under more rigorous short-circuited conditions and, in particular, can be used for screening putative 1α-hydroxyl analogs of vitamin D in nephrectomized rats.     

The Myriad Plant Responses to Herbivores

Abstract Plant responses to herbivores are complex. Genes activated on herbivore attack are strongly correlated with the mode of herbivore feeding and the degree of tissue damage at the feeding site. Phloem-feeding whiteflies and aphids that produce little injury to plant foliage are perceived as pathogens and activate the salicylic acid (SA)-dependent and jasmonic acid (JA)/ethylene-dependent signaling pathways. Differential expression of plant genes in response to closely related insect species suggest that some elicitors generated by phloem-feeding insects are species-specific and are dependent on the herbivore's developmental stage. Other elicitors for defense-gene activation are likely to be more ubiquitous. Analogies to the pathogen-incompatible reactions are found. Chewing insects such as caterpillars and beetles and cell-content feeders such as mites and thrips cause more extensive tissue damage and activate wound-signaling pathways. Herbivore feeding is not equivalent to mechanical wounding. Wound responses are a part of the induced responses that accompany herbivore feeding. Herbivores induce direct defenses that interfere with herbivore feeding, growth and development, fecundity, and fertility. In addition, herbivores induce an array of volatiles that creates an indirect mechanism of defense. Volatile blends provide specific cues to attract herbivore parasites and predators to infested plants. The nature of the elicitors for volatile production is discussed.     

Increased heterozygosity and allele variants are seen in Texel compared to Suffolk sheep

In this study, the Suffolk and Texel sheep breeds were compared for microsatellite marker heterozygosity throughout seven chromosomal regions in the sheep genome. A total of 623 Texel animals and 489 Suffolk animals in five and three half-sib families, respectively, were genotyped for microsatellite markers across the seven different chromosomes. Using the observed allele frequencies, the expected levels of heterozygosity were calculated for each family. The expected levels of heterozygosity did not significantly differ between the breeds across all regions studied. However, levels of expected heterozygosity were 32% higher in Texel animals on chromosome 4 due to a region of increased heterozygosity between BMS648 and BM3212. The number of allelic variants significantly differed between the breeds, solely due to a region of increased number of alleles on chromosome 20. This region of higher numbers of allele variants in the Texel breed extended from the MHC to c. 15 cM distal to the MHC region incorporating markers OMHC1, CSRD226, TGLA387 and BM1818, which had 3.30, 7.02, 3.09 and 6.75 more alleles in Texel than in Suffolk animals, respectively. No difference was observed in the variance of allele frequency between the two breeds. It is proposed that previous selective sweeps may have reduced numbers of alleles and levels of heterozygosity in the Suffolk breed.     

Immunological Characterization of a Tapetal Protein in Developing Anthers of Lilium longiflorum

Antiserum was raised in rabbits against a lily (Lilium longiflorum) anther-specific protein (LLA-15). Monospecific anti-LLA-15 antibodies were prepared to investigate the distribution of LLA-15 during anther development in a variety of flowering plants. Immunoblot analyses of total protein from floral and vegetative organs confirmed that LLA-15 or LLA-15-like proteins accumulated to detectable levels only in a discrete stage of anther development. In situ localization using anti-rabbit immunoglobulin G conjugated with gold particles confirmed that LLA-15 was specifically localized in the tapetal tissue of lily anthers. The maximal level of LLA-15 was strictly coincident with the peak of tapetal secretory functions. Immunoblots of two-dimensional polyacrylamide gels of lily anther proteins indicated that the seven LLA-15 isoforms ranged from isoelectric point 5.6 to 6.1. In vitro translation of lily anther mRNAs showed that four of these isoforms were primary products, the additional three being a result of posttranslational processing of the primary translation products.     

Do competing males cooperate? Familiarity and its effect on cooperation during predator inspection in male three‐spined sticklebacks (Gasterosteus aculeatus)

We investigated the trade‐off between conflict and cooperation, using predator inspection behaviour in sticklebacks as a model system. Male three‐spined sticklebacks ( Gasterosteus aculeatus ) compete for territories during the breeding season and it has been demonstrated that the level of aggression between territorial neighbours declines with time, a phenomenon known as the dear enemy effect. In this experiment we examine whether this increase in familiarity between territorial neighbours can facilitate an increase in cooperation during predator inspection events. This was analyzed using male sticklebacks from four pond populations, two with and two without predatory rainbow trout ( Oncorhyncus mykiss ). Males were each exposed to five different treatments: (1) the presentation of a live rainbow trout when alone; (2) with a newly revealed territorial neighbour; (3) with this neighbour after two days of familiarization; (4) with another unfamiliar neighbour (termed a 'floater'); and (5) a second solitary trial (to provide controls at the start and end of the experiment). As predicted, fish from predator‐sympatric populations showed higher levels of predator inspection and lower rates of misdirected territorial aggression towards the predator throughout. However, familiarity between neighbouring males did not facilitate an increase in predator inspection behaviour. Instead, predator inspection behaviour decreased throughout treatments involving the presence of any sort of neighbouring male. Familiarity between neighbours did not influence their ability to cooperatively inspect, but only the nature of any aggressive territorial behaviours, all of which detracted equally from individual inspection effort.     

Body macronutrient composition is predicted by lipid and not protein content of the diet

Diet is an important determinant of fitness‐related traits including growth, reproduction, and survival. Recent work has suggested that variation in protein:lipid ratio and particularly the amount of protein in the diet is a key nutritional parameter. However, the traits that mediate the link between dietary macronutrient ratio and fitness‐related traits are less well understood. An obvious candidate is body composition, given its well‐known link to health. Here, we investigate the relationship between dietary and body macronutrient composition using a first‐generation laboratory population of a freshwater fish, the three‐spine stickleback (Gasterosteus aculeatus). Carbohydrate is relatively unimportant in the diet of predatory fish, facilitating the exploration of how dietary protein‐to‐lipid ratio affects their relative deposition in the body. We find a significant effect of lipid intake, rather than protein, on body protein:lipid ratio. Importantly, this was not a result of absorbing macronutrients in relation to their relative abundance in the diet, as the carcass protein:lipid ratios differed from those of the diets, with ratios usually lower in the body than in the diet. This indicates that individuals can moderate their utilization, or uptake, of ingested macronutrients to reach a target balance within the body. We found no effect of diet on swimming endurance, activity, or testes size. However, there was an effect of weight on testes size, with larger males having larger testes. Our results provide evidence for the adjustment of body protein:lipid ratio away from that of the diet. As dietary lipid intake was the key determinant of body composition, we suggest this occurs via metabolism of excess protein, which conflicts with the predictions of the protein leverage hypothesis. These results could imply that the conversion and excretion of protein is one of the causes of the survival costs associated with high‐protein diets.