Evidence for reproductive isolation between cave bear populations

The European cave bear (Ursus spelaeus), which became extinct around 15,000 years ago, had several morphologically different forms. Most conspicuous of these were small Alpine cave bears found at elevations of 1,600 to 2,800 m. Whereas some paleontologists have considered these bears a distinct form, or even a distinct species, others have disputed this. By a combination of morphological and genetic methods, we have analyzed a population of small cave bears from Ramesch Cave (2,000 m altitude) and one of larger cave bears from Gamssulzen Cave (1,300 m), situated approximately 10 km apart in the Austrian Alps (Figure 1A). We find no evidence of mitochondrial gene flow between these caves during the 15,000 years when they were both occupied by cave bears, although mitochondrial DNA sequences identical to those from Gamssulzen Cave could be recovered from a site located about 200 km to the south in Croatia. We also find no evidence that the morphology of the bears in the two caves changed to become more similar over time. We suggest that the two cave bear forms may have represented two reproductively isolated subspecies or species.     

The development of semicircular canals in the inner ear: role of FGFs in sensory cristae

In the vertebrate inner ear, the ability to detect angular head movements lies in the three semicircular canals and their sensory tissues, the cristae. The molecular mechanisms underlying the formation of the three canals are largely unknown. Malformations of this vestibular apparatus found in zebrafish and mice usually involve both canals and cristae. Although there are examples of mutants with only defective canals, few mutants have normal canals without some prior sensory tissue specification, suggesting that the sensory tissues, cristae, might induce the formation of their non-sensory components, the semicircular canals. We fate-mapped the vertical canal pouch in chicken that gives rise to the anterior and posterior canals, using a fluorescent, lipophilic dye (DiI), and identified a canal genesis zone adjacent to each prospective crista that corresponds to the Bone morphogenetic protein 2 (Bmp2)-positive domain in the canal pouch. Using retroviruses or beads to increase Fibroblast Growth Factors (FGFs) for gain-of-function and beads soaked with the FGF inhibitor SU5402 for loss-of-function experiments, we show that FGFs in the crista promote canal development by upregulating Bmp2. We postulate that FGFs in the cristae induce a canal genesis zone by inducing/upregulating Bmp2 expression. Ectopic FGF treatments convert some of the cells in the canal pouch from the prospective common crus to a canal-like fate. Thus, we provide the first molecular evidence whereby sensory organs direct the development of the associated non-sensory components, the semicircular canals, in vertebrate inner ears.     

Rhesus factors and ammonium: a function in efflux?

Completion of fungal, plant and human genomes paved the way to the identification of erythrocytic rhesus proteins and their kidney homologs as ammonium transporters.     

Stored cysteine proteinases start globulin mobilization in protein bodies of embryonic axes and cotyledons during vetch (Vicia sativa L.) seed germination

Inhibition of protein synthesis by cycloheximide during vetch seed germination, did not prevent globulin breakdown as indicated by a decrease in vicilin- and legumin-specific immunosignals on Western blots. Protein bodies isolated from embryo axes and cotyledons of dry vetch (Vicia sativa L.) seeds using a non-aqueous method were found to be free of cytoplasmic and organellar contaminations. Lysates of these purified protein bodies were capable of degrading globulins; this process was blocked by the cysteine proteinase (CPR) inhibitor iodoacetic acid. Protein bodies contained the papain-like CPR2 and CPR4, and the legumain-like CPR VsPB2. In vitro assays showed that albumin extracts from protein bodies degraded oligopeptide substrates in the PepTag-Assay and degraded the legumain substrate N-benzoyl-asparaginyl-p-nitroanilide. We conclude that, during germination, globulin mobilization is initiated by stored CPRs in protein bodies of embryonic axes as well as cotyledons, and that de-novo-formed proteolytic enzymes mainly mediate bulk degradation of stored globulin in cotyledons after germination. Received: 14 February 2000 / Accepted: 16 August 2000     

Characterization of dog cardiac microsomes Use of zonal centrifugation to fractionate fragmented sarcoplasmic reticulum, (Na + K)-activated ATPase and mitochondrial fragments

Cardiac microsomes represent a heterogeneous fraction which contains mitochondrial, plasma membrane and lysosomal enzymes in addition to markers believed to originate in the sarcoplasmic reticulum. The exact composition of this fraction depends on the method of preparation in that prolonged homogenization of ventricular myocardium increases both the yield of microsomal protein and the proportion of the mitochondrial contaminant.

Ultracentrifugation of cardiac microsomes on density gradients made with sucrose alone is of limited value in isolating fragmented sarcoplasmic reticulum. Because of aggregation of the microsomes, zonal ultracentrifugation in sucrose permits isolation of material with only slight enhancement in the activity of markers for the sarcoplasmic reticulum. In the presence of LiBr, used under conditions which inhibit the damaging effects of this salt on the activities studied, aggregation of the microsomal fraction is reduced and density gradient fractionation is more effective.

The fragmented sarcoplasmic reticulum prepared by zonal centrifugation in 0.5 M LiBr contains less than 1/5 the level of mitochondrial enzymes found in the original microsomes while the rate of Ca²⁺ uptake is enhanced 2-fold and the extent of Ca²⁺ uptake is enhanced 4-fold over that in the crude microsomal fraction. The sarcoplasmic reticulum markers were concentrated in a region of the gradient containing approx. 5% of the original protein that did not correspond to an obvious protein peak.     

Improving the health behaviours of elderly people: randomised controlled trial of a general practice education programme

ObjectivesTo establish the effect of an educational intervention for general practitioners on the health behaviours and wellbeing of elderly patients.DesignRandomised controlled trial with 1 year follow up.SettingMetropolitan general practices in Melbourne, Australia.Subjects42 general practitioners and 267 of their patients aged over 65 years.InterventionEducational and clinical practice audit programme for general practitioners on health promotion for elderly people.ResultsPatients in the intervention group had increased (a) walking by an average of 88 minutes per fortnight, (b) frequency of pleasurable activities, and (c) self rated health compared with the control group. No change was seen in drug usage, rate of influenza vaccination, functional status, or psychological wellbeing as a result of the intervention. Extrapolations of the known effect of these changes in behaviour suggest mortality could be reduced by 22% if activity was sustained for 5 years.ConclusionsEducation of the general practitioners had a positive effect on health outcomes of their elderly patients. General practitioners may have considerable public health impact in promotion of health for elderly patients.

Key messages

• Few educational interventions for doctors have shown benefit to the health of patients
• Elderly people were identified in the UK health initiatives as in need of additional attention, and levels of health protective behaviours were low in community surveys
• A multifaceted educational intervention for general practitioners was effective in improving walking behaviour, self rated health status, and the frequency of social contacts in elderly patients
• General practitioners are effective in improving health and health behaviours in their elderly patients

     

Crystal structure of the bromide-bound D85S mutant of bacteriorhodopsin: principles of ion pumping

We report the crystal structure of a bromide-bound form of the D85S mutant of bacteriorhodopsin, bR(D85S), a protein that uses light energy rather than ATP to pump halide ions across the cell membrane. Comparison of the structure of the halide-bound and halide-free states reveals that both displacements of individual side-chain positions and concerted helical movements occur on the extracellular side of the protein. Analysis of these structural changes reveals how this ion pump first facilitates ion uptake deep within the cell membrane and then prevents the backward escape of ions later in the pumping cycle. Together with the information provided by structures of intermediate states in the bacteriorhodopsin photocycle, this study also suggests the overall design principles that are necessary for ion pumping.     

Fast and accurate determination of sites along the FUT2 in vitro transcript that are accessible to antisense oligonucleotides by application of secondary structure predictions and RNase H in combination with MALDI-TOF mass spectrometry

Alteration of gene expression by use of antisense oligonucleotides has considerable potential for therapeutic purposes and scientific studies. Although applied for almost 25 years, this technique is still associated with difficulties in finding antisense-effective regions along the target mRNA. This is mainly due to strong secondary structures preventing binding of antisense oligonucleotides and RNase H, playing a major role in antisense-mediated degradation of the mRNA. These difficulties make empirical testing of a large number of sequences complementary to various sites in the target mRNA a very lengthy and troublesome procedure. To overcome this problem, more recent strategies to find efficient antisense sites are based on secondary structure prediction and RNase H-dependent mechanisms. We were the first who directly combined these two strategies; antisense oligonucleotides complementary to predicted unpaired target mRNA regions were designed and hybridized to the corresponding RNAs. Incubation with RNase H led to cleavage of the RNA at the respective hybridization sites. Analysis of the RNA fragments by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, which has not been used in this context before, allowed exact determination of the cleavage site. Thus the technique described here is very promising when searching for effective antisense sites.