The whereabouts of an ancient wanderer: global phylogeography of the solitary ascidian Styela plicata

Genetic tools have greatly aided in tracing the sources and colonization history of introduced species. However, recurrent introductions and repeated shuffling of populations may have blurred some of the genetic signals left by ancient introductions. Styela plicata is a solitary ascidian distributed worldwide. Although its origin remains unclear, this species is believed to have spread worldwide by travelling on ship's hulls. The goals of this study were to infer the genetic structure and global phylogeography of S. plicata and to look for present-day and historical genetic patterns. Two genetic markers were used: a fragment of the mitochondrial gene Cytochrome Oxidase subunit I (COI) and a fragment of the nuclear gene Adenine Nucleotide Transporter/ADP-ATP Translocase (ANT). A total of 368 individuals for COI and 315 for ANT were sequenced from 17 locations worldwide. The levels of gene diversity were moderate for COI to high for ANT. The Mediterranean populations showed the least diversity and allelic richness for both markers, while the Indian, Atlantic and Pacific Oceans had the highest gene and nucleotide diversities. Network and phylogenetic analyses with COI and ANT revealed two groups of alleles separated by 15 and 4 mutational steps, respectively. The existence of different lineages suggested an ancient population split. However, the geographic distributions of these groups did not show any consistent pattern, indicating different phylogeographic histories for each gene. Genetic divergence was significant for many population-pairs irrespective of the geographic distance among them. Stochastic introduction events are reflected in the uneven distribution of COI and ANT allele frequencies and groups among many populations. Our results confirmed that S. plicata has been present in all studied oceans for a long time, and that recurrent colonization events and occasional shuffling among populations have determined the actual genetic structure of this species.     

Contrasting Microbial Community Assembly Hypotheses: A Reconciling Tale from the Río Tinto

Background

The Río Tinto (RT) is distinguished from other acid mine drainage systems by its natural and ancient origins. Microbial life from all three domains flourishes in this ecosystem, but bacteria dominate metabolic processes that perpetuate environmental extremes. While the patchy geochemistry of the RT likely influences the dynamics of bacterial populations, demonstrating which environmental variables shape microbial diversity and unveiling the mechanisms underlying observed patterns, remain major challenges in microbial ecology whose answers rely upon detailed assessments of community structures coupled with fine-scale measurements of physico-chemical parameters.

Methodology/Principal Findings

By using high-throughput environmental tag sequencing we achieved saturation of richness estimators for the first time in the RT. We found that environmental factors dictate the distribution of the most abundant taxa in this system, but stochastic niche differentiation processes, such as mutation and dispersal, also contribute to observed diversity patterns.

Conclusions/Significance

We predict that studies providing clues to the evolutionary and ecological processes underlying microbial distributions will reconcile the ongoing debate between the Baas Becking vs. Hubbell community assembly hypotheses.     

Morphological analysis of three equivocal sibling species of Deprea (Solanaceae)

Taxonomic confusion among closely related and morphologically similar Deprea species has persisted in the literature and in the identification of species. Morphological variation among three closely related, monophyletic Deprea species was studied to determine if and how they can be distinguished. Their sympatric occurrence in Venezuela afforded an opportunity to couple field study with analysis of herbarium specimens representing their entire geographic range. An analysis of 94 morphological characters resulted in five vegetative and 13 reproductive taxonomically informative traits. Canonical variates analysis clearly separated the three species using six quantitative traits. We conclude that these taxa, although quite variable and similar morphologically, are taxonomically distinct. Results of character analysis indicated that D. orinocensis is morphologically more similar to D. bitteriana than either are to D. paneroi. In D. paneroi, small, sterile anthers on fruit-bearing plants and the absence of fruits on plants possessing large, plllen-bearing anthers, suggest cryptic dioecy. Based on these data, D. granulosa is considered to be a synonym of D. orinocensis: Athenaea bitteriana, a misapplied synonym, is the correct basionym and is applicable to many specimens identified as D. granulosa. We submit a new combination, D. bitteriana (Werderm.) Sawyer & Benítez, and designate a lectotype to accommodate these findings.     

Modulation of histamine-induced Ca2+ release by protein kinase C. Effects on cytosolic and mitochondrial [Ca2+] peaks

In HeLa cells, histamine induces production of inositol 1,4,5-trisphosphate (InsP3) and release of Ca2+ from the endoplasmic reticulum (ER). Ca2+ release is typically biphasic, with a fast and brief initial phase, followed by a much slower and prolonged one. In the presence of inhibitors of protein kinase C (PKC), including staurosporine and the specific inhibitors GF109203X and Ro-31-8220, the fast phase continued until the ER became fully empty. On the contrary, treatment with phorbol 12,13-dibutyrate inhibited Ca2+ release. Staurosporine had no effect on InsP3-induced Ca2+ release in permeabilized cells and did not modify either histamine-induced InsP3 production. These data suggest that histamine induces Ca2+ release and with a short lag activates PKC to down-regulate it. Consistently, Ca2+ oscillations induced by histamine were increased in amplitude and decreased in frequency in the presence of PKC inhibitors. We show also that mitochondrial [Ca2+] was much more sensitive to changes in ER-Ca2+ release induced by PKC modulation than cytosolic [Ca2+]. PKC inhibitors increased the histamine-induced mitochondrial [Ca2+] peak by 4-fold but increased the cytosolic [Ca2+] peak only by 20%. On the contrary, PKC activation inhibited the mitochondrial [Ca2+] peak by 90% and the cytosolic one by only 50%. Similarly, the combination of PKC inhibitors with the mitochondrial Ca2+ uniporter activator SB202190 led to dramatic increases in mitochondrial [Ca2+] peaks, with little effect on cytosolic ones. This suggests that activation of ER-Ca2+ release by PKC inhibitors could be involved in apoptosis induced by staurosporine. In addition, these mechanisms allow flexible and independent regulation of cytosolic and mitochondrial [Ca2+] during cell stimulation.     

Bitrophic toxicity of Cry1Ac to Cycloneda sanguinea,a predator in Brazilian cotton

Insect predators are exposed to the Cry1Ac toxin in Bt cotton fields through several pathways. In this study, we investigated the effects of activated Cry1Ac added to a diet on Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), which is one of the main predators of non‐target pests in Brazilian cotton. Direct bitrophic exposure of C. sanguinea to Cry1Ac was done by feeding beetles with Aphis gossypii (Glover) (Hemiptera: Aphidae) sprayed with 500 μg per ml Cry1Ac solution. Larval and pupal survival, development time, aphid consumption, and adult longevity were recorded daily. Couples within the same experimental treatment were paired and numbers of eggs laid and hatched per female were recorded daily. Net replacement rate was calculated for each female. During development, a C. sanguinea larva consumed on average 1.8 μg of activated Cry1Ac. No significant differences due to Cry1Ac were observed for any of the response variables, except aphid consumption. Larvae receiving Cry1Ac consumed more aphids than larvae receiving distilled water alone. Additional statistical analyses were conducted to evaluate independence of responses, and for the independent responses, a simple meta‐analysis was conducted to test the null hypothesis that all responses were zero. Nearly all of the response variables were statistically independent. Two pairs of responses were not independent, but the associated multivariate tests were not significant. The meta‐analysis suggested that all effects were not different from random variation around zero and no cumulative effects could be detected. Our results indicated that bitrophic exposure to activated Cry1Ac is likely to have little or no adverse ecological effect on C. sanguinea.     

Spores morphology and synangia in neotropical fern species of Marattia (Marattiaceae)

The Marattiaceae are represented by a small family of four to six genera that bear esporogenous structures of two types: sorus with free eusporangia in Angiopteris and Archangiopteris, and indurated synangium in Christensenia, Danaea and Marattia. Marattia is a pantropical genus of about eight to ten species in the paleotropic and seven to eight species in the neotropic. In order to describe the spores and sinangia morphology, this study analyzed the shape of the receptacles, and the position of the synangia, and evaluated the spores with SEM, of seven neotropical species of the genus Marattia: M. alata, M. cicutifolia, M. excavata, M. interposita, M. laevis, M. laxa y M. weinmanniifolia from several collections. The receptacles were fully developed in M. cicutifolia and M. laevis, and scarcely overelevated in the rest of the species. The synangium was ellipsoidal and had intramarginal to supramedial position in the laminae. The spores of Marattia were elliptic. Among the taxa, only monolete spores were found, with no trilete, aborted or deformed spores. The laesura was linear and reached about two of the total length of the spore. The perispore appears as a continuous thin layer deposited on the exospore according to its ornamentation in M. cicutifolia and M. laevis. It is smooth in M. alata, rugate in M. excavata and pustulate-rugate in two species: M. interposita and M. laxa. The exospore is echinate in M. cicutifolia and M. laevis and pustulate in the other species. In M. weinmannifolia spores produced by the same sinangium may have different ornamentation types. We concluded that, while the presence of ellipsoidal and superficial synangia and monolete spores aperture were generic traits, the micro and macro-ornamentation types of the perispores and exospores vary at specific level. Besides, macro-ornamentation can be bulliform (pustulate), a combination of bulliform and muriform types (pustulate-rugate), muriform (rugate-retate) and stelliform (echinate); finally, granular micro-ornamentation can be seen frecuently in perispores.     

In vitro differentiation of human mesenchymal stem cells to epithelial lineage

Our study examined whether human bone marrow-derived MSCs are able to differentiate, in vitro, into functional epithelial-like cells. MSCs were isolated from the sternum of 8 patients with different hematological disorders. The surface phenotype of these cells was characterized.To induce epithelial differentiation, MSCs were cultured using Epidermal Growth Factor, Keratinocyte Growth Factor, Hepatocyte Growth Factor and Insulin-like growth Factor-II. Differentiated cells were further characterized both morphologically and functionally by their capacity to express markers with specificity for epithelial lineage. The expression of cytokeratin 19 was assessed by immunocytochemistry, and cytokeratin 18 was evaluated by quantitative RT-PCR (Taq-man). The data demonstrate that human MSCs isolated from human bone marrow can differentiate into epithelial-like cells and may thus serve as a cell source for tissue engineering and cell therapy of epithelial tissue.