Convergent evolution of floral signals underlies the success of Neotropical orchids

The great majority of plant species in the tropics require animals to achieve pollination, but the exact role of floral signals in attraction of animal pollinators is often debated. Many plants provide a floral reward to attract a guild of pollinators, and it has been proposed that floral signals of non-rewarding species may converge on those of rewarding species to exploit the relationship of the latter with their pollinators. In the orchid family (Orchidaceae), pollination is almost universally animal-mediated, but a third of species provide no floral reward, which suggests that deceptive pollination mechanisms are prevalent. Here, we examine floral colour and shape convergence in Neotropical plant communities, focusing on certain food-deceptive Oncidiinae orchids (e.g. Trichocentrum ascendens and Oncidium nebulosum) and rewarding species of Malpighiaceae. We show that the species from these two distantly related families are often more similar in floral colour and shape than expected by chance and propose that a system of multifarious floral mimicry—a form of Batesian mimicry that involves multiple models and is more complex than a simple one model–one mimic system—operates in these orchids. The same mimetic pollination system has evolved at least 14 times within the species-rich Oncidiinae throughout the Neotropics. These results help explain the extraordinary diversification of Neotropical orchids and highlight the complexity of plant–animal interactions.     

Assessing the conservation status of soil‐dwelling vertebrates: Insights from the rediscovery of Typhlops uluguruensis (Reptilia: Serpentes: Typhlopidae)

Soil‐dwelling amphibians and reptiles are relatively poorly studied and understood. Difficulties in sampling these taxa in their subterranean habitats might impede assessments of their conservation status. We explore this issue with a case study of the burrowing scolecophidian snake Typhlops uluguruensis, endemic to the Uluguru Mountains in the Eastern Arc of Tanzania. Despite recent standard faunistic surveys, there have been no reported sightings or collections of T. uluguruensis since the type series of four specimens was collected in 1926. Intensive replacement of forest by agriculture in the vicinity of the type locality had led to concern about the conservation status of this and other species. We report the rediscovery of T. uluguruensis in low intensity agriculture adjacent to human habitation, and close to the type locality. We compare the new material with the type series, and discuss the implications of this rediscovery for conservation assessments of small, soil‐dwelling lower vertebrates. We advise caution in determining conservation status when, as is usually the case, no special sampling of the soil has been carried out. Additionally, relatively neglected disturbed habitats should also be given more attention. Standard sampling methods for soil‐dwelling vertebrates need to be further developed and established.     

Cystic fibrosis carrier population screening in the primary care setting.

To determine the receptivity of prenatal care providers and their patients to carrier testing for cystic fibrosis (CF), we offered free carrier screening, followed by genetic counseling of carriers, to all prenatal care providers in Rochester, NY, for all their female patients of reproductive age, pregnant or not. Of 124 prenatal care providers, only 37 elected to participate, but many of these offered screening only to pregnant women. The acceptance rate among pregnant women was approximately 57%. The most common reasons for accepting screening were to obtain reassurance (50.7%) and to avoid having a child with CF (27.8 %). The most common reasons for declining screening were not intending to terminate a pregnancy for CF (32.4%) and believing that the chance of having a CF child was very low (32.2%). Compared with decliners, acceptors were more likely to have no children, regarded having a child with CF as more serious, believed themselves more susceptible to having such a child, knew more about CF, would be more likely to terminate a pregnancy if the fetus were shown to have CF, and more strongly supported offering CF screening to women of reproductive age. Of 4,879 women on whom results were obtained, 124 were found to be carriers. Of these 124 carriers, the partners of 106 were tested. Of the five at-risk couples, four requested prenatal diagnosis and one requested neonatal diagnosis. No woman found to be a carrier whose partner tested negative requested prenatal diagnosis. Except for the imperfect knowledge of those testing negative, none of the adverse outcomes predicted for CF carrier testing in the general population were observed in this study.     

Intra-articular injection of micronized dehydrated human amnion/chorion membrane attenuates osteoarthritis development

Introduction

Micronized dehydrated human amnion/chorion membrane (μ-dHACM) is derived from donated human placentae and has anti-inflammatory, low immunogenic and anti-fibrotic properties. The objective of this study was to quantitatively assess the efficacy of μ-dHACM as a disease modifying intervention in a rat model of osteoarthritis (OA). It was hypothesized that intra-articular injection of μ-dHACM would attenuate OA progression.

Methods

Lewis rats underwent medial meniscal transection (MMT) surgery to induce OA. Twenty four hours post-surgery, μ-dHACM or saline was injected intra-articularly into the rat joint. Naïve rats also received μ-dHACM injections. Microstructural changes in the tibial articular cartilage were assessed using equilibrium partitioning of an ionic contrast agent (EPIC-μCT) at 21 days post-surgery. The joint was also evaluated histologically and synovial fluid was analyzed for inflammatory markers at 3 and 21 days post-surgery.

Results

There was no measured baseline effect of μ-dHACM on cartilage in naïve animals. Histological staining of treated joints showed presence of μ-dHACM in the synovium along with local hypercellularity at 3 and 21 days post-surgery. In MMT animals, development of cartilage lesions at 21 days was prevented and number of partial erosions was significantly reduced by treatment with μ-dHACM. EPIC-μCT analysis quantitatively showed that μ-dHACM reduced proteoglycan loss in MMT animals.

Conclusions

μ-dHACM is rapidly sequestered in the synovial membrane following intra-articular injection and attenuates cartilage degradation in a rat OA model. These data suggest that intra-articular delivery of μ-dHACM may have a therapeutic effect on OA development.     

Influence of lipids on the hydrophobic barrier within the pore of the TWIK-1 K2P channel

Several recent ion channel structures have revealed large side portals, or ‘fenestrations’ at the interface between their transmembrane helices that potentially expose the ion conduction pathway to the lipid core of the bilayer. In a recent study we demonstrated that functional activity of the TWIK-1 K2P channel is influenced by the presence of hydrophobic residues deep within the inner pore. These residues are located near the fenestrations in the TWIK-1 structure and promote dewetting of the pore by forming a hydrophobic barrier to ion conduction. During our previous MD simulations, lipid tails were observed to enter these fenestrations. In this addendum to that study, we investigate lipid contribution to the dewetting process. Our results demonstrate that lipid tails from both the upper and lower leaflets can occupy the fenestrations and partially penetrate into the pore. The lipid tails do not sterically occlude the pore, but there is an inverse correlation between the presence of water within the hydrophobic barrier and the number of lipids tails within the lining of the pore. However, dewetting still occurs in the absence of lipids tails, and pore hydration appears to be determined primarily by those side-chains lining the narrowest part of the pore cavity.     

Prenatal hemoglobinopathy screening. IV. Follow-up of women at risk for a child with a clinically significant hemoglobinopathy.

To determine the benefits and burdens of prenatal hemoglobinopathy carrier identification and genetic counseling and its impact on subsequent reproductive behavior, we recontacted women whom we had previously identified as at risk for having a child with a clinically significant hemoglobinopathy, regardless of whether they had accepted the offer of prenatal diagnosis. Of the 46 such women, 31 were available for interview. These 31 women had received offers of prenatal diagnosis in 47 pregnancies. Seventeen had been accepted, and 30 had been declined. The proportion of patients accepting the offer of prenatal diagnosis was higher for the index pregnancy (50%) than for subsequent pregnancies (22%). The mean interval between the initial counseling of the patient and the follow-up interview was 43 mo (standard error +/- 2.7 mo). Ninety-four percent of those interviewed recalled having received information from the screening program; 74% recalled the name of their condition; 90% knew that trait did not affect their health; 84% recalled the name of the condition for which their fetus had been at risk; and 77% could state at least one symptom of the disease. Of the 29 women asked whether they intended to use prenatal diagnosis in future pregnancies, 13 said yes and 16 said no. Of the 26 patients asked about satisfaction with their previous decision about prenatal diagnosis, all were satisfied with their decision. Eighteen said they would make the same decision in their next pregnancy, but seven patients said they would not, and one was undecided.(ABSTRACT TRUNCATED AT 250 WORDS)     

Low‐intensity microwave irradiation does not substantially alter gene expression in late larval and adult Caenorhabditis elegans

Reports that low‐intensity microwave radiation induces heat‐shock reporter gene expression in the nematode, Caenorhabditis elegans, have recently been reinterpreted as a subtle thermal effect caused by slight heating. This study used a microwave exposure system (1.0 GHz, 0.5 W power input; SAR 0.9–3 mW kg^?1 for 6‐well plates) that minimises temperature differentials between sham and exposed conditions (≤0.1 °C). Parallel measurement and simulation studies of SAR distribution within this exposure system are presented. We compared five Affymetrix gene arrays of pooled triplicate RNA populations from sham‐exposed L4/adult worms against five gene arrays of pooled RNA from microwave‐exposed worms (taken from the same source population in each run). No genes showed consistent expression changes across all five comparisons, and all expression changes appeared modest after normalisation (≤40% up‐ or down‐regulated). The number of statistically significant differences in gene expression (846) was less than the false‐positive rate expected by chance (1131). We conclude that the pattern of gene expression in L4/adult C. elegans is substantially unaffected by low‐intensity microwave radiation; the minor changes observed in this study could well be false positives. As a positive control, we compared RNA samples from N2 worms subjected to a mild heat‐shock treatment (30 °C) against controls at 26 °C (two gene arrays per condition). As expected, heat‐shock genes are strongly up‐regulated at 30 °C, particularly an hsp‐70 family member (C12C8.1) and hsp‐16.2. Under these heat‐shock conditions, we confirmed that an hsp‐16.2::GFP transgene was strongly up‐regulated, whereas two non‐heat‐inducible transgenes (daf‐16::GFP; cyp‐34A9::GFP) showed little change in expression. Bioelectromagnetics 30:602–612, 2009. © 2009 Wiley‐Liss, Inc.