Failure of testicular development associated with a rearrangement of 9p24.1 proximal to the SNF2 gene

In 46,XY individuals, testes are determined by the activity of the SRY gene (sex-determining region Y), located on the short arm of the Ychromosome. The other genetic components of the cascade that leads to testis formation are unknown and may be located on the Xchromosome or on the autosomes. Evidence for the existence of several loci associated with failure of male sexual development is indicated by reports of 46,XY gonadal dysgenesis associated with structural abnormalities of the Xchromosome or of autosomes (chromosomes9, 10, 11 and 17). In this report, we describe the investigation of a child presenting with multiple congenital abnormalities, mental retardation and partial testicular failure. The patient had a homogeneous de novo 46,XY,inv dup(9)(pter→p24.1::p21.1 →p23.3::p24.1→qter) chromosome complement. No deletion was found by either cytogenetic or molecular analysis. The SRY gene and DSS region showed no abnormalities. Southern blotting dosage analysis with 9p probes and fluorescent in situ hybridisation data indicated that the distal breakpoint of the duplicated fragment was located at 9p24.1, proximal to the SNF2 gene. We therefore suggest that a gene involved in normal testicular development and/or maintenance is present at this position on chromosome 9. Received: 20 January 1997 / Accepted: 5 November 1997     

Expanded thermal niche for a diving vertebrate: A leatherback turtle diving into near-freezing water

The global distribution of extant reptiles is more limited than that of mammals or birds, with low reptilian species diversity at high latitudes. Central to this limited geographical distribution is the ectothermic nature of reptiles, which means that they generally become torpid at cold temperatures. However, here we report the first detailed telemetry from a leatherback turtle (Dermochelys coriacea) diving in cold water at high latitude. An individual equipped with a satellite tag that relayed temperature-depth profiles dived continuously for many weeks into sub-surface waters as cold as 0.4 °C. Global warming will likely increase the foraging range of leatherback turtles further into temperate and boreal waters.     

Neto2 Interacts with the Scaffolding Protein GRIP and Regulates Synaptic Abundance of Kainate Receptors

Kainate receptors (KARs) are a class of ionotropic glutamate receptors that are expressed throughout the central nervous system. The function and subcellular localization of KARs are tightly regulated by accessory proteins. We have previously identified the single-pass transmembrane proteins, Neto1 and Neto2, to be associated with native KARs. In the hippocampus, Neto1, but not Neto2, controls the abundance and modulates the kinetics of postsynaptic KARs. Here we evaluated whether Neto2 regulates synaptic KAR levels in the cerebellum where Neto1 expression is limited to the deep cerebellar nuclei. In the cerebellum, where Neto2 is present abundantly, we found a ∼40% decrease in GluK2-KARs at the postsynaptic density (PSD) of Neto2-null mice. No change, however, was observed in total level of GluK2-KARs, thereby suggesting a critical role of Neto2 on the synaptic localization of cerebellar KARs. The presence of a putative class II PDZ binding motif on Neto2 led us to also investigate whether it interacts with PDZ domain-containing proteins previously implicated in regulating synaptic abundance of KARs. We identified a PDZ-dependent interaction between Neto2 and the scaffolding protein GRIP. Furthermore, coexpression of Neto2 significantly increased the amount of GRIP associated with GluK2, suggesting that Neto2 may promote and/or stabilize GluK2:GRIP interactions. Our results demonstrate that Neto2, like Neto1, is an important auxiliary protein for modulating the synaptic levels of KARs. Moreover, we propose that the interactions of Neto1/2 with various scaffolding proteins is a critical mechanism by which KARs are stabilized at diverse synapses.     

Remote Sensing of Climatic Anomalies and West Nile Virus Incidence in the Northern Great Plains of the United States

The northern Great Plains (NGP) of the United States has been a hotspot of West Nile virus (WNV) incidence since 2002. Mosquito ecology and the transmission of vector-borne disease are influenced by multiple environmental factors, and climatic variability is an important driver of inter-annual variation in WNV transmission risk. This study applied multiple environmental predictors including land surface temperature (LST), the normalized difference vegetation index (NDVI) and actual evapotranspiration (ETa) derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) products to establish prediction models for WNV risk in the NGP. These environmental metrics are sensitive to seasonal and inter-annual fluctuations in temperature and precipitation, and are hypothesized to influence mosquito population dynamics and WNV transmission. Non-linear generalized additive models (GAMs) were used to evaluate the influences of deviations of cumulative LST, NDVI, and ETa on inter-annual variations of WNV incidence from 2004–2010. The models were sensitive to the timing of spring green up (measured with NDVI), temperature variability in early spring and summer (measured with LST), and moisture availability from late spring through early summer (measured with ETa), highlighting seasonal changes in the influences of climatic fluctuations on WNV transmission. Predictions based on these variables indicated a low WNV risk across the NGP in 2011, which is concordant with the low case reports in this year. Environmental monitoring using remote-sensed data can contribute to surveillance of WNV risk and prediction of future WNV outbreaks in space and time.     

Temperature,deltamethrin-resistance status and performance measures of Plutella xylostella: complex responses of insects to environmental variables

1. Worldwide, the excessive use of insecticides has resulted in field-evolved insecticide-resistant populations of diamondback moth (DBM), Plutella xylostella. A deltamethrin-resistant DBM population from the field was divided into two subpopulations in the laboratory. One population (S-strain) was maintained with no further exposure to insecticides, whereas the other population (R-strain) was maintained under a regime of intermittent selection with deltamethrin. 2. Individuals from both strains were reared at constant temperatures in the range 10–35 °C in the absence of deltamethrin, and the effects of rearing temperature on various traits were investigated. At the time of experimentation, the R-strain was 20-fold more resistant to deltamethrin than the S-strain. 3. Temperature differentially affected developmental time, adult life span, pupal weight, and fecundity of both strains. Although both strains laid eggs after being reared at 10 °C, few of these eggs were fertile. The R-strain developed significantly faster than the S-strain. The integrated performance of the S-strain and R-strain was greatest at 25 and 15 °C, respectively. 4. The present study provides important information on the complexities of the outcomes of the interactions between ectotherms and temperature. Specifically, temperature-trait relationships may not be unimodal, and ectotherm genotypes (in this case insecticide-resistance status) and abiotic stresses can interact with unpredictable outcomes. 5. Current models predicting DBM population dynamics and relative abundance in different locations do not consider different thermal biologies of different genotypes. The present study shows the dramatic effects of environment on many parameters used in these models and will help to enhance their accuracy, and thus their utility.     

A Temporally Explicit Production Efficiency Model for Fuel Load Allocation in Southern Africa

Abstract We present a regional fuel load model (1 km² spatial resolution) applied in the southern African savanna region. The model is based on a patch-scale production efficiency model (PEM) scaled up to the regional level using empirical relationships between patch-scale behavior and multi-source remote sensing data (spatio-temporal variability of vegetation and climatic variables). The model requires the spatial distribution of woody vegetation cover, which is used to determine separate respiration rates for tree and grass. Net primary production, grass and tree leaf death, and herbivory are also taken into account in this mechanistic modeling approach. The fuel load model has been calibrated and validated from independent measurements taken from savanna vegetation in Africa southward from the equator. A sensitivity analysis on the effect of climate variables (incoming radiation, air temperature, and precipitation) has been conducted to demonstrate the strong role that water availability has in determining productivity and subsequent fuel load over the southern African region. The model performance has been tested in four different areas representative of a regional increasing rainfall gradient—Etosha National Park, Namibia, Mongu and Kasama, Zambia, as well as in Kruger National Park, South Africa. Within each area, we analyze model output from three different magnitudes of canopy coverage (<5, 30, and 50%). We find that fuel load ranges predicted by the model are globally in agreement with field measurements for the same year. High rainfall sustains green herbaceous production late in the dry season and delays tree leaf litter production. Effect of water on production varies across the rainfall gradient with delayed start of green material production in more arid regions.