Variability in response to UV-B among species and strains of Metarhizium isolated from sites at latitudes from 61 degrees N to 54 degrees S.

The effects of irradiances of 920 and 1200 mW m(-2) (biologically effective weighted irradiance) were examined in 2 Metarhizium album strains, 26 M. anisopliae strains, 1 M. flavoviride strain, and 1 M. taii strain isolated from sites located at latitudes from 61 degrees N to 54 degrees S. Conidia were exposed to UV-B from 1 to 6 h and subsequently examined for relative percentage culturability. Total dosage received at the end of the exposure periods ranged from 3.3 to 19.9 kJ m(-2) for the lower irradiance and from 4.3 to 25.9 kJ m(-2) for the higher irradiance. Both the irradiance values and the doses are environmentally realistic and can be observed even in temperate regions. The relationships between latitude of origin and UV-B tolerance were compared for the two levels of irradiance for the data from 1 and 2 h exposure. Exposure to both irradiances drastically reduced the relative percentage culturability of all strains. Tolerance to UV-B varied widely among strains and high variation was observed for both irradiances after all periods of exposure. After 1 h of exposure, a difference between the two irradiance levels was detectable, and this difference was magnified at longer irradiations. A significant quadratic relationship of decreasing UV-B tolerance with increasing latitude was observed after exposure of 1 and 2 h. The shape of the relationship did not differ for the two levels of irradiance. Also, we studied the effect of 1200 mW m(-2) irradiance on conidial germination time in 1 M. album strain, 7 M. anisopliae strains, and 1 M. taii strain. Exposure to UV-B delayed the germination of surviving conidia of all strains. In general, the delay in germination was directly proportional to the dose.     

β-thalassemia mutations in the Portuguese population

Summary In this study we have carried out haplotype analysis on the -globin gene cluster and characterized the -thalassemia mutation by oligonucleotide hybridization in 14 patients with thalassemia major and 5 with sickle cell/-thalassemia originating from southern Portugal. We found that three mutations, namely the °-39, ° IVS-1 nt 1 and ⁺ IVS-1 nt 110 are prevalent accounting for 53%, 32% and 10% of the -thalassemia chromosomes respectively. In general each mutation was associated with a specific chromosomal haplotype; the ° mutation, however, was linked to three different haplotypes. These results indicate that three oligo-probes complementary to the most common mutations allow prenatal diagnosis by oligonucleotide analysis in 96% of the couples at risk of having offspring with thalassemia major in southern Portugal.     

Demonstration of a beta-casomorphin immunoreactive material in the plasma of newborn calves after milk intake

Blood was collected from newborn calves before and after their first milk intake after birth; extracts of plasma were assayed by radioimmunoassay for the presence of beta-casomorphin-7 immunoreactive materials. No beta-casomorphin immunoreactivity was found in samples collected before milk ingestion; however, in samples collected after milk ingestion a beta-casomorphin-7 immunoreactive material was detected. Chromatographic characterization showed that this material was not identical with beta-casomorphin-7 but might rather represent a precursor thereof. The material proved resistant to enzymatic attack during a 30-min incubation period at 37 degrees C in the plasma of newborn calves, whereas beta-casomorphin-7 was degraded under these conditions. A physiological significance of beta-casomorphin-7 eventually cleaved from such a precursor material at any site in the newborn mammal is suggested.     

The molecular basis for Duchenne versus Becker muscular dystrophy: Correlation of severity with type of deletion

About 60% of both Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) is due to deletions of the dystrophin gene. For cases with a deletion mutation, the "reading frame" hypothesis predicts that BMD patients produce a semifunctional, internally deleted dystrophin protein, whereas DMD patients produce a severely truncated protein that would be unstable. To test the validity of this theory, we analyzed 258 independent deletions at the DMD/BMD locus. The correlation between phenotype and type of deletion mutation is in agreement with the "reading frame" theory in 92% of cases and is of diagnostic and prognostic significance. The distribution and frequency of deletions spanning the entire locus suggests that many "in-frame" deletions of the dystrophin gene are not detected because the individuals bearing them are either asymptomatic or exhibit non-DMD/non-BMD clinical features.     

Molecular deletion patterns in Duchenne and Becker type muscular dystrophy

Summary DNA from 80 Duchenne (DMD) and 15 Becker (BMD) index patients was analyzed with 12 genomic probes and the total cDNA. Deletions were detected in 24 DMD (30%) and 10 BMD patients (67%) by genomic probes alone, mostly p20, pXJ, and/or pERT87. All deletions were confirmed by cDNA probes, and an additional 29 DMD deletions were detected, resulting in a total of 63/95 deletions (66%). The majority of the deletions are localized between kb 6.7 and 9.7 of the cDNA; a smaller group, between kb 0.5 and 3.5. Of the deletions, 90% are detected by the three cDNA probes 1–2a, 7, and 8. This can be applied to strategies for carrier detection and prenatal diagnosis. The order of 13 exon-containing HindIII fragments in the region between probes 7 and 9–10, where most of the deletions are found, could be defined. The deletion patterns in DMD and BMD patients are different and well in accordance with the “reading frame theory” of Monaco and coworkers. Thus our findings indicate that a DMD or BMD phenotype may be predicted according to the breakpoint position and the number of deleted exons.     

Ion balance in tomato cultivars differing in salt tolerance. I. Sodium and potassium accumulation and fluxes under moderate salinity

The magnitude of sodium and potassium fluxes in Lycopersicon escutentum cuhivars Ace and Edkawi (Edkawi is considered more sait-tolerant I was evaluated in planls grown for 10 days in aerated Hoagland solution with the addition of 25 or 100 mM NaCl. Ion accumulatiun in different plant pans, ion concentration in xylem exudate. transpiration and membrane leakiness were measured. Both cultivars responded very similarly to these levels of salinity in terms of growth. No conspicuous differences in membrane leakiness were observed. Net uprake rates were calculated from ion contents data. Potassium uptake rates were lower in salinized planls than in controls, especially in cv. Aee. Potassium/sodium selectivity ratios were much higher in Edkawi than in Ace. and higher in shoot uptake rates than in xy lem exudate. This indicates that Edakw i has a higher capacity to retain potassium under salinity, a character which could contribute to its salt-tolerance.     

Human appropriation of net primary production as driver of change in landscape-scale vertebrate richness

Aim

Land use is the most pervasive driver of biodiversity loss. Predicting its impact on species richness (SR) is often based on indicators of habitat loss. However, the degradation of habitats, especially through land-use intensification, also affects species. Here, we evaluate whether an integrative metric of land-use intensity, the human appropriation of net primary production, is correlated with the decline of SR in used landscapes across the globe.

Location

Global.

Time period

Present.

Major taxa studied

Birds, mammals and amphibians.

Methods

Based on species range maps (spatial resolution: 20 km × 20 km) and an area-of-habitat approach, we calibrated a “species–energy model” by correlating the SR of three groups of vertebrates with net primary production and biogeographical covariables in “wilderness” areas (i.e., those where available energy is assumed to be still at pristine levels). We used this model to project the difference between pristine SR and the SR corresponding to the energy remaining in used landscapes (i.e., SR loss expected owing to human energy extraction outside wilderness areas). We validated the projected species loss by comparison with the realized and impending loss reconstructed from habitat conversion and documented by national Red Lists.

Results

Species–energy models largely explained landscape-scale variation of mapped SR in wilderness areas (adjusted R²-values: 0.79–0.93). Model-based projections of SR loss were lower, on average, than reconstructed and documented ones, but the spatial patterns were correlated significantly, with stronger correlation in mammals (Pearson's r = 0.68) than in amphibians (r = 0.60) and birds (r = 0.57).

Main conclusions

Our results suggest that the human appropriation of net primary production is a useful indicator of heterotrophic species loss in used landscapes, hence we recommend its inclusion in models based on species–area relationships to improve predictions of land-use-driven biodiversity loss.     

Induced responses in three tropical dry forest plant species – direct and indirect effects on herbivory

Induced changes in plant quality are hypothesized to reduce herbivore numbers and subsequent damage to the plant. The resultant decrease in herbivory may be due to direct negative impacts on herbivores, through the reduction in foliage quality as food, or due to indirect effects of plant-induced traits interacting with the third trophic level, increasing predation and parasitism rates on herbivores. The relative importance of induced responses as direct and/or indirect defenses has not been evaluated in natural systems. Moreover, few studies have evaluated the influence of early-season damage on late-season herbivory in natural systems, particularly in the tropics. The presence of induced responses and subsequent impact on folivory as a consequence of early-season damage were evaluated in three plant species ( Croton pseudoniveus , Bursera instabilis and Piper stipulaceum ) in a tropical dry forest in Mexico. A two-factorial experiment was applied to determine if induced responses influenced subsequent herbivory directly, by reducing foliage quality, or indirectly, through their interaction with parasitoids and predatory arthropods. Plants from all three species with reduced early-season damage had higher herbivory rates through the rest of the growing season, compared to plants that were damaged during leaf expansion. Chemical analyses showed that early-season damage induced the production of total phenolics and condensed tannins for C. pseudoniveus and B. instabilis , respectively. The mechanism by which these compounds affected subsequent herbivory was most likely by directly reducing foliage quality as food for herbivores, given that predatory arthropods and parasitoids had no effects on herbivory in this study. I conclude that early-season damage in these three species influenced later-season herbivory through the induction of plant responses that may act to reduce plant quality as food for herbivores.