Oxygen deficiency affects carbohydrate reserves in overwintering forage crops

Anaerobic conditions developing under an ice cover affect winter survival and spring regrowth of economically important perennial crops. The objective was to compare, during a prolonged period of low (<2%) O2 at low temperature, the concentration of carbohydrates of four plant species contrasting in their resistance to oxygen deficiency. Four perennial forage species, lucerne (Medicago sativa L.), red clover (Trifolium pratense L.), timothy (Phleum pratense L.), and cocksfoot (Dactylis glomerata L.) were subjected to a progressively developing oxygen deficiency stress by enclosing potted plants in gas-tight bags in late autumn for overwintering in an unheated greenhouse. Timothy was previously reported to be more resistant to oxygen deficiency than the three other species. Non-structural carbohydrates increased and remained at a higher concentration in timothy than in the other three species under low O2 concentration. Concentrations of sucrose, fructose, glucose, and fructans increased in response to oxygen deficiency in timothy, whereas the concentration of soluble sugars decreased under the same conditions in lucerne, red clover, and cocksfoot. The gene expression of glyceraldehyde-3-phosphate dehydrogenase increased in response to low oxygen concentration in oxygen deficiency-sensitive lucerne while it remained unchanged in the oxygen deficiency-resistant timothy. It is concluded that timothy maintains higher carbohydrate reserves under oxygen deficiency, a specific feature that could favour its winter survival and spring regrowth.     

Metastasis of bronchogenic carcinoma to the thumb

Bone metastasis in the hand is rare. The etiology is quite different from that of metastasis to other bones; bronchogenic carcinoma is by far the most frequent case. Distal phalanges are mainly involved with irregular osteolysis and cortical destruction. Differential diagnosis of phalangeal metastasis includes osteomyelitis, rheumatoid arthritis and gout. The prognosis is always that of metastatic bronchial cancer with an average survival of three months. Treatment may involve distal digital amputation or antalgic radiotherapy. A case of bronchogenic carcinoma with metastasis to the thumb is presented. The metastasis was located in the distal phalanx of the left thumb. The primary tumor was located in the lung. Treatment consisted of amputation. The overall survival was five months.     

Microsatellite variation in Drosophila melanogaster and Drosophila simulans: a reciprocal test of the ascertainment bias hypothesis

Interspecific comparisons of microsatellite loci have repeatedly shown that the loci are longer and more variable in the species from which they are derived (the focal species) than are homologous loci in other (nonfocal) species. There is debate as to whether this is due to directional evolution or to an ascertainment bias during the cloning and locus selection processes. This study tests these hypotheses by performing a reciprocal study. Eighteen perfect dinucleotide microsatellite loci identified from a Drosophila simulans library screen and 18 previously identified in an identical Drosophila melanogaster library screen were used to survey natural populations of each species. No difference between focal and nonfocal species was observed for mean PCR fragment length. However, heterozygosity and number of alleles were significantly higher in the focal species than in the nonfocal species. The most common allele in the Zimbabwe population of both species was sequenced for 31 of the 36 loci. The length of the longest stretch of perfect repeat units is, on average, longer in the focal species than in the non-focal species. There is a positive correlation between the length of the longest stretch of perfect repeats and heterozygosity. The difference in heterozygosity can thus be explained by a reduction in the length of the longest stretch of perfect repeats in the nonfocal species. Furthermore, flanking-sequence length difference was noted between the two species at 58% of the loci sequenced. These data do not support the predictions of the directional-evolution hypothesis; however, consistent with the ascertainment bias hypothesis, the lower variability in nonfocal species is an artifact of the microsatellite cloning and isolation process. Our results also suggest that the magnitude of ascertainment bias for repeat unit length is a function of the microsatellite size distribution in the genomes of different species.      

Prospects for estimating nucleotide divergence with RAPDs

The technique of random amplification of polymorphic DNA (RAPD), which is simply polymerase chain reaction (PCR) amplification of genomic DNA by a single short oligonucleotide primer, produces complex patterns of anonymous polymorphic DNA fragments. The information provided by these banding patterns has proved to be of great utility for mapping and for verification of identity of bacterial strains. Here we consider whether the degree of similarity of the banding patterns can be used to estimate nucleotide diversity and nucleotide divergence. With haploid data, fragments generated by RAPD-PCR can be treated in a fashion very similar to that for restriction-fragment data. Amplification of diploid samples, on the other hand, requires consideration of the fact that presence of a band is dominant to absence of the band. After describing a method for estimating nucleotide divergence on the basis of diploid samples, we summarize the restrictions and criteria that must be met when RAPD data are used for estimating population genetic parameters.      

Which physicians make home visits and why? A survey

BACKGROUND: Recent changes in the North American health care system and certain demographic factors have led to increases in home care services. Little information is available to identify the strategies that could facilitate this transformation in medical practice and ensure that such changes respond adequately to patients'' needs. As a first step, the authors attempted to identify the major factors influencing physicians'' home care practices in the Quebec City area. METHODS: A self-administered questionnaire was sent by mail to all 696 general practitioners working in the Quebec City area. The questionnaire was intended to gather information on physicians'' personal and professional characteristics, as well as their home care practice (practice volume, characteristics of both clients and home visits, and methods of patient assessment and follow-up). RESULTS: A total of 487 physicians (70.0%) responded to the questionnaire, 283 (58.1%) of whom reported making home visits. Of these, 119 (42.0%) made fewer than 5 home visits per week, and 88 (31.1%) dedicated 3 hours or less each week to this activity. Physicians in private practice made more home visits than their counterparts in family medicine units and CLSCs (centres locaux des services communautaires [community centres for social and health services]) (mean 11.5 v. 5.8 visits per week), although the 2 groups reported spending about the same amount of time on this type of work (mean 5.6 v. 5.0 hours per week). The proportion of visits to patients in residential facilities or other private residences was greater for private practitioners than for physicians from family medicine units and CLSCs (29.7% v. 18.9% of visits), as were the proportions of visits made at the patient''s request (28.0% v. 14.2% of visits) and resulting from an acute condition (21.4% v. 16.0% of visits). The proportion of physicians making home visits at the request of a CLSC was greater for those in family medicine units and CLSCs than for those in private practice (44.0% v. 11.3% of physicians), as was the proportion of physicians making home visits at the request of a colleague (18.0% v. 4.5%) or at the request of hospitals (30.0% v. 6.8%). Physicians in family medicine units and CLSCs did more follow-ups at a frequency of less than once per month than private practitioners (50.9% v. 37.1% of patients), and they treated a greater proportion of patients with cognitive disorders (17.2% v. 12.6% of patients) and palliative care needs (13.7% v. 8.6% of patients). Private practitioners made less use of CLSC resources to assess home patients or follow them. Male private practitioners made more home visits than their female counterparts (mean 12.8 v. 8.3 per week), although they spent an almost equal amount of time on this activity (mean 5.7 v. 5.2 hours per week). INTERPRETATION: These results suggest that practice patterns for home care vary according to the physician''s practice setting and sex. Because of foreseeable increases in the numbers of patients needing home care, further research is required to evaluate how physicians'' practices can be adapted to patients'' needs in this area.     

R-state hemoglobin bound to heterotropic effectors: models of the DPG, IHP and RSR13 binding sites

We performed a docking study followed by a 500-ps molecular dynamics simulation of R-state human adult hemoglobin (HbA) complexed to different heterotropic effectors [2,3-diphosphoglycerate (DPG), inositol hexaphosphate (IHP), and 2-[4-[(3,5-dichlorophenylcarbamoyl)-]methyl]-phenoxy]-2-methylpropionic acid (RSR13)) to propose a molecular basis for recently reported interactions of effectors with oxygenated hemoglobin. The simulations were carried out with counterions and explicit solvation. As reported for T-state HbA, the effector binding sites are also located in the central cavity of the R-state and differ depending on effector anionic character. DPG and IHP bind between the alpha-subunits and the RSR13 site spans the alpha1-, alpha2- and beta2-subunits. The generated models provide the first report of the molecular details of R-state HbA bound to heterotropic effectors.     

The dnaJ (hsp40) locus in Rhizobium leguminosarum bv. phaseoli is required for the establishment of an effective symbiosis with Phaseolus vulgaris

P121R25 is a Tn5-induced mutant of the effective Rhizobium leguminosarum bv. phaseoli strain P121R that is unable to use glutamate as the sole carbon and nitrogen source and is defective in symbiotic nitrogen fixation. Enzymatic analysis showed that three enzymes implicated in glutamate metabolism (glutamate dehydrogenase, 2-oxoglutarate dehydrogenase, and glutamate synthase) were affected by this mutation. Sequencing of the chromosomal locus bordering the Tn5 in P121R25 indicated the presence of the dnaK and dnaJ genes in an arrangement similar to that described in R. leguminosarum bv. viciae (GenBank accession number Y14649). The mutation was located in the dnaJ (hsp40) gene.