Reproductive biology and mating system estimates of two Andean melocacti, Melocactus schatzlii and M. andinus (Cactaceae)

BACKGROUND AND AIMS: The genus Melocactus comprises 36 species of globose cacti with the most derived traits in the Cereeae tribe. It is the proper study system to examine what are the most derived reproductive strategies within that tribe. This study aims to characterize the reproductive biology and to estimate the mating system parameters of two Andean melocacti, Melocactus schatzlii and M. andinus. METHODS: The reproductive attributes of the two species were described, including floral morphology, anthesis patterns, floral rewards, floral visitors and visitation patterns. Levels of self-compatibility and autonomous self-pollination were estimated by hand-pollination experiments. Mating system estimates were obtained by conducting progeny array analyses using isozymes. KEY RESULTS: The flowers of the two species present the typical hummingbird-pollination syndrome. Despite their morphological resemblance, the two species differ in flower size, pollen and ovule production and anthesis pattern. Their main pollinator agents are hummingbirds, four species in M. schatzlii and one species in M. andinus. Both cacti are self-compatible and capable of self-pollination without the aid of pollen vectors. Population-level outcrossing rate was higher for M. schatzlii (t(m)=0.9) than for M. andinus (t(m)=0.4). At the family level, outcrossing rates for most mothers of M. schatzlii were higher (t(m)>0.8) than for M. andinus (t(m)<0.5). CONCLUSIONS: Although the two cacti are capable of selfing, M. schatzlii is a predominantly outcrossing species, while M. andinus behaves as a mixed-mating cactus. Hummingbirds are the only pollinators responsible for outcrossing and gene flow events in these species. In their absence, both melocacti set seeds by selfing. Based on its low population size, restricted distribution in Venezuela, low rates of floral visits, and high levels of inbreeding, M. andinus is considered to be an endangered species deserving further study to define its conservation status.     

A phosphatase activity of Sts-1 contributes to the suppression of TCR signaling

Precise signaling by the T cell receptor (TCR) is crucial for a proper immune response. To ensure that T cells respond appropriately to antigenic stimuli, TCR signaling pathways are subject to multiple levels of regulation. Sts-1 negatively regulates signaling pathways downstream of the TCR by an unknown mechanism(s). Here, we demonstrate that Sts-1 is a phosphatase that can target the tyrosine kinase Zap-70 among other proteins. The X-ray structure of the Sts-1 C terminus reveals that it has homology to members of the phosphoglycerate mutase/acid phosphatase (PGM/AcP) family of enzymes, with residues known to be important for PGM/AcP catalytic activity conserved in nature and position in Sts-1. Point mutations that impair Sts-1 phosphatase activity in vitro also impair the ability of Sts-1 to regulate TCR signaling in T cells. These observations reveal a PGM/AcP-like enzyme activity involved in the control of antigen receptor signaling.     

Factors influencing owner satisfaction with companion-dog-training facilities

The aim of this study was to survey people currently attending companion-dog-training facilities about their reasons for attending training, their expectations prior to training, their training experiences, and the factors contributing to their satisfaction with these experiences. The 178 participants indicated that they experienced few canine behavioral difficulties prior to attending training, with factors other than dog behavior influencing their decision to attend a particular facility. Features identified as important were characteristics of the instructors and the facility itself, opportunities for the dog caretaker (owner) to develop dog-training skills and knowledge, and specific canine behavior outcomes. Satisfaction was a multidimensional concept: satisfaction with the instructors and facility being dissociable from satisfaction with progress made by the dog and handler. Each of these represented different aspects of the training experience. Training facilities may need to address a wide range of issues to engage additional dog owners in training activities. Identification of these issues is an important first step in this process.     

Sprouty2 binds Grb2 at two different proline-rich regions, and the mechanism of ERK inhibition is independent of this interaction

Sprouty2 has been widely implicated in the negative regulation of the fibroblast growth factor receptor-extracellular regulated kinase (ERK) pathway. Sprouty2 directly interacts with the adapter protein Grb2, member of the receptor tyrosine kinase-induced signaling pathways. In considering the functional role of Grb2, we investigated whether the interaction with this protein was responsible for ERK pathway inhibition. We found that the binding between Sprouty2 and Grb2 is constitutive, independent of Sprouty2 tyrosine phosphorylation, although it is increased when fibroblast growth factor receptor is activated. This connection is mediated by the N-terminal SH3 domain of Grb2 and two Sprouty2 proline-rich stretches (residues 59-64 and 303-307). Most importantly, a double Sprouty2 mutant (hSpry2 P59AP304A), which is unable to bind Grb2, developed at a similar inhibition level of fibroblast growth factor receptor-ERK pathway than that which originated from Sprouty2 wt. These results are evidence that the Sprouty2 mechanism of ERK inhibition is independent of Grb2 binding.     

Selective cytotoxicity of Pancratistatin-related natural <Emphasis Type="Italic">Amaryllidaceae</Emphasis> alkaloids: evaluation of the activity of two new compounds

Background  

Pancratistatin (PST), a compound extracted from an Amaryllidaceae (AMD) family plant, has been shown to specifically induce apoptosis in cancer cells with no/minimal toxic effect on normal cells. A systematic synthetic approach has indicated that the minimum cytotoxic pharmacophore comprises the trans-fused b/c-ring system containing the 2, 3, 4-triol unit in the C-ring. To further explore the structure-activity relationship of this group of compounds we have investigated the anti-cancer efficacy and specificity of two PST-related natural compounds, AMD4 and AMD5. Both of these compounds lack the polyhydroxylated lycorane element of PST instead having a methoxy-substuituted crinane skeleton.     

Evolution of opsin expression in birds driven by sexual selection and habitat

Theories of sexual and natural selection predict coevolution of visual perception with conspecific colour and/or the light environment animals occupy. One way to test these theories is to focus on the visual system, which can be achieved by studying the opsin-based visual pigments that mediate vision. Birds vary greatly in colour, but opsin gene coding sequences and associated visual pigment spectral sensitivities are known to be rather invariant across birds. Here, I studied expression of the four cone opsin genes (Lws, Rh2, Sws2 and Sws1) in 16 species of New World warblers (Parulidae). I found levels of opsin expression vary both across species and between the sexes. Across species, female, but not male Sws2 expression is associated with an index of sexual selection, plumage dichromatism. This fits predictions of classic sexual selection models, in which the sensory system changes in females, presumably impacting female preference, and co-evolves with male plumage. Expression of the opsins at the extremes of the light spectrum, Lws and Uvs, correlates with the inferred light environment occupied by the different species. Unlike opsin spectral tuning, regulation of opsin gene expression allows for fast adaptive evolution of the visual system in response to natural and sexual selection, and in particular, sex-specific selection pressures.     

SWS2 visual pigment evolution as a test of historically contingent patterns of plumage color evolution in warblers

Distantly related clades that occupy similar environments may differ due to the lasting imprint of their ancestors—historical contingency. The New World warblers (Parulidae) and Old World warblers (Phylloscopidae) are ecologically similar clades that differ strikingly in plumage coloration. We studied genetic and functional evolution of the short‐wavelength‐sensitive visual pigments (SWS2 and SWS1) to ask if altered color perception could contribute to the plumage color differences between clades. We show SWS2 is short‐wavelength shifted in birds that occupy open environments, such as finches, compared to those in closed environments, including warblers. Phylogenetic reconstructions indicate New World warblers were derived from a finch‐like form that colonized from the Old World 15–20 Ma. During this process, the SWS2 gene accumulated six substitutions in branches leading to New World warblers, inviting the hypothesis that passage through a finch‐like ancestor resulted in SWS2 evolution. In fact, we show spectral tuning remained similar across warblers as well as the finch ancestor. Results reject the hypothesis of historical contingency based on opsin spectral tuning, but point to evolution of other aspects of visual pigment function. Using the approach outlined here, historical contingency becomes a generally testable theory in systems where genotype and phenotype can be connected.     

Comparative Proteomics of Ovarian Cancer Aggregate Formation Reveals an Increased Expression of Calcium-activated Chloride Channel Regulator 1 (CLCA1)

Ovarian cancer is a lethal gynecological disease that is characterized by peritoneal metastasis and increased resistance to conventional chemotherapies. This increased resistance and the ability to spread is often attributed to the formation of multicellular aggregates or spheroids in the peritoneal cavity, which seed abdominal surfaces and organs. Given that the presence of metastatic implants is a predictor of poor survival, a better understanding of how spheroids form is critical to improving patient outcome, and may result in the identification of novel therapeutic targets. Thus, we attempted to gain insight into the proteomic changes that occur during anchorage-independent cancer cell aggregation. As such, an ovarian cancer cell line, OV-90, was cultured in adherent and non-adherent conditions using stable isotope labeling with amino acids in cell culture (SILAC). Anchorage-dependent cells (OV-90AD) were grown in tissue culture flasks, whereas anchorage-independent cells (OV-90AI) were grown in suspension using the hanging-drop method. Cellular proteins from both conditions were then identified using LC-MS/MS, which resulted in the quantification of 1533 proteins. Of these, 13 and 6 proteins were up-regulated and down-regulated, respectively, in aggregate-forming cells compared with cells grown as monolayers. Relative gene expression and protein expression of candidates were examined in other cell line models of aggregate formation (TOV-112D and ES-2), which revealed an increased expression of calcium-activated chloride channel regulator 1 (CLCA1). Moreover, inhibitor and siRNA transfection studies demonstrated an apparent effect of CLCA1 on cancer cell aggregation. Further elucidation of the role of CLCA1 in the pathogenesis of ovarian cancer is warranted.