Turnover of plant lineages shapes herbivore phylogenetic beta diversity along ecological gradients

Understanding drivers of biodiversity patterns is of prime importance in this era of severe environmental crisis. More diverse plant communities have been postulated to represent a larger functional trait‐space, more likely to sustain a diverse assembly of herbivore species. Here, we expand this hypothesis to integrate environmental, functional and phylogenetic variation of plant communities as factors explaining the diversity of lepidopteran assemblages along elevation gradients in the Swiss Western Alps. According to expectations, we found that the association between butterflies and their host plants is highly phylogenetically structured. Multiple regression analyses showed the combined effect of climate, functional traits and phylogenetic diversity in structuring butterfly communities. Furthermore, we provide the first evidence that plant phylogenetic beta diversity is the major driver explaining butterfly phylogenetic beta diversity. Along ecological gradients, the bottom up control of herbivore diversity is thus driven by phylogenetically structured turnover of plant traits as well as environmental variables.     

Molecular diagnosis of Duchenne and Becker muscular dystrophies. Current data

Carrier diagnosis and prenatal diagnosis of Duchenne's muscular dystrophy (DMD) and Becker's muscular dystrophy (BMD) has become possible using some twenty RFLPs detected by more than a dozen Xp21 probes that are either intragenic or flanking the disease locus. Results from familial studies on 88 DMD and BM families stress important considerations concerning a priori and final risks, individuals necessary for the identification of the phase, and the different strategies that can be applied, regardless of whether the study concerns an on-going pregnancy or a carrier-status determination, and whether the patient is at high or low risk. Finally, multiple sources of difficulties in interpreting the results depend on a) the occurrence of new mutations that must be traced; b) the existence of meiotic recombination; c) the necessity, in some instances, of relying upon the sole identification of the paternal X. These considerations emphasize the characteristics and the important limitations of this type of methodology.     

Cellular and molecular biology of Alzheimer's disease

Alzheimer's disease results from the degeneration of neurons. Degenerating nerve cells express atypical proteins, and amyloid is deposited. We suggest that some of these events are strongly influenced by genetic factors and age. Animal models should be useful in investigating the pathogenic mechanisms that lead to the brain abnormalities seen in this disease.     

Selective illumination of single photoreceptors in the house fly retina: local membrane turnover and uptake of extracellular horseradish peroxidase (HRP) and Lucifer Yellow

Summary Single photoreceptor cells in the compound eye of the housefly Musca domestica were selectively illuminated and subsequently compared electron-microscopically with the unilluminated photoreceptors in the immediate surroundings. The rhabdomeres of the illuminated cells remain largely unaffected, but the cells show an increase in the number of coated pits, various types of vesicles, and degradative organelles; some of the latter organelles are described for the first time in fly photoreceptors. Coated pits are found not only at the bases of the microvilli, but also in other parts of the plasma membrane. Degradative organelles, endoplasmic reticulum (ER) and mitochondria aggregate in the perinuclear region. The rough ER and smooth ER are more elaborate, the number of Golgi stacks, free ribosomes and polysomes is increased, and the shape and distribution of heterochromatin within the nuclei are altered. Illuminated photoreceptors also interdigitate extensively with their neighbouring secondary pigment cells. These structural changes in illuminated fly photoreceptor cells indicate an increase in membrane turnover and cellular metabolism. When applied to the eye, Lucifer Yellow spreads into the extracellular space and is taken up only by the illuminated photoreceptor cells. These cells show the same structural modifications as above. Horseradish peroxidase applied in the same way is observed in pinocytotic vesicles and degradative organelles of the illuminated cells. Hence, the light-induced uptake of extracellular compounds takes place in vivo at least partially as a result of an increase in pinocytosis.     

Membrane-damaging action of ricin on DPPC and DPPC-cerebrosides assemblies

Perturbations induced by a toxic lectin (ricin) on lipid organisation of model membranes prepared with DPPC and DPPC-cerebrosides mixtures have been analysed by Raman and infrared spectroscopy, two powerful and non-invasive methods. Our approach involves the observation of changes in the vibrational spectra of liquid multilayers in the PO ₂ ^- , C=0 and CH₂ spectral regions for two lipid: ricin molar ratios (225:1, 75:1).The interfacial and polar regions of the multilayers, analysed by FTIR, appear to be perturbed by the protein. With both kinds of membranes, ricin mainly perturbs the C=0 ester groups of the sn-2 acylchain of DPPC. In the PO ₂ ^- stretching region, the frequency shifts are correlated with changes in polar group hydration.In the hydrophobic core of the multilayer membrane studied by Raman spectroscopy, the interaction of ricin is associated with changes in lipid packing. These perturbations depend upon the lipid composition of the membrane. With DPPC membranes, an affect is detected at temperatures lower than T _m .It corresponds to a decrease of the lipid ordering. With DPPC-cer membranes, the protein increases the acylchain packing order regardless of the temperature of the experiments (10°C<T<75°C). No perturbation of T _m is observed after addition of ricin to either DPPC or DPPC-cer membranes.The different perturbations detected by Raman and FTIR suggest that ricin mainly interacts with the interfacial domains of the membranes.     

The purification of an erythroid protein which binds to enhancer and promoter elements of haemoglobin genes.

An erythroid nuclear protein (EF1), originally detected as a protein binding within the nuclease hypersensitive site upstream of the chicken beta H-globin gene, has been purified. This protein of 37,000-39,000 molecular weight binds to three sites within the hypersensitive region: one between the CCAAT and TATA boxes, the second (further upstream) next to a NF1 binding site, and the third adjacent to a regulatory element found in a number of beta-globin genes. The EF1 protein also binds to an erythroid-specific promoter element of the mouse alpha-globin gene and to two sites within the chicken beta A-globin enhancer. These six EF1-binding sites are related by the consensus sequence A/TGATAA/GG/C. A minor protein of molecular weight 72,000 which co-purifies with EF1 also binds to the same sequences.     

Changes in the cellular permeability of the embryonic axis inGcer arietinum L. seeds during germination

The effect of short chain fatty acids on the cellular permeability of embryonic axis inGcer arietinum seeds was studied. Octanoic (OCT) and nonanoic (NON) adds, which reduce both germination and growth of the embryonic axis and raise the inhibitor effects of the supraoptimal temperatures (30?C), induce a greater ionic efflux into the medium (conductivity). NON reduces glucose (3-0-MG) and K⁺ (⁸⁶Rb) uptake during the germinative process, this action being counteracted by fusicoccin (FC) at optimal (25?C) and supraoptimal temperatures (30 ?C). Tonoplast and plasmalemma increase their permeability to the K⁺ efflux when NON is present. Addition of NON+FC gives rise to higher values in the efflux rate, the vacuolar compartment being the most affected. Temperatures around zero (2 ?C) notably reduce the isotope efflux from cytosol and vacuole. NON acid does not significantly affect the efflux of³H-ABA, suggesting that it does not cause any important changes in the phytohormone compartmentation.