Transmission and recombination of extranuclear genes during sexual crosses in Aspergillus nidulans

Summary Three extranuclear mitochondrial mutations in Aspergillus nidulans, (oliA1), (camA1) and (cs67), were used as markers in sexual crosses to provide information on the frequencies of transmission and recombination of the mitochondrial genome. Any individual perithecium contained ascospores of only one extranuclear genotype.Using mono-, bi- and trifactorial crosses it was found that all three markers could be recovered from the progeny, although the transmission frequencies were different for each marker. This bias was present irrespective of the nuclear background or the presence of selective agents in the medium on which the cross was established. These findings enable a series of transmission strength to be established, as shown below:- (cs67,{\text{ }}camA1) > ( + ) = (cs67) > (oliA1,cs67) \hfill \\ {\text{ }} > (oliA1) > (oliA1,{\text{ }}camA1) \hfill \\ \end{gathered} $$ " align="middle" border="0"> However, the numbers of recombinants isolated were so variable as to make this form of analysis unsuitable for mapping the mitochondrial genome.     

The major human erythrocyte membrane protein. Evidence for an S-shaped structure which traverses the membrane twice and contains a duplicated set of sites.

The structure of the major human erythrocyte membrane protein (protein E) was investigated by studying the products of proteolysis of the native protein in the membrane. The distribution and location of the tyrosine residues labelled by radioiodination by lactoperoxidase was determined. Proteolysis of the extracellular region of the protein by thermolysin released four tyrosine-containing peptides, all of which were also found to remain in the major fragment that is retained in the membrane. The presence of these duplicated sites in the extracellular region of the protein was confirmed by limited trypsin digestion of the intracellular region of the protein. Two groups of fragments were obtained. Both groups contained a set of the extracellular labelled sites, but they differed in containing distinct groups of intracellular sites, showing that the two sets of extracellular sites are linked by an intracellular region of the protein. The polypeptide chain thus traverses the membrane twice. An S-shaped model which is consistent with these data is proposed.     

Effects of ovariectomy of the dogfish Scyliorhinus canicula L. on circulating levels of androgen and oestradiol and on pituitary gonadotrophin content

Levels of androgens and oestradiol in dogfish, Scyliorhinus canicula , plasma, measured by radioimmunoassay, decrease markedly after ovariectomy (OVX). The magnitude and latency of these responses varies according to length of captivity preceding the operation and the time of year at which ovariectomy is performed. Androgens are cleared more rapidly than oestradiol from plasma following OVX, and levels of both steroids are reduced after laparotomy (LAP) in November but not in March. An extract of ventral lobes of the dogfish pituitary induces a significant increase in the circulating androgen levels in LAP fish but not in OVX fish, indicating that the ovary is the major site of androgen production in response to stimulation by dogfish gonadotrophin. Intramuscular injections of oestradiol benzoate (2.5 mg per fish) into LAP fish produce a significant reduction in the gonadotrophin content of the pituitary ventral lobe, measured in the quail testicular cell bioassay, when compared to LAP and unoperated controls. However, no significant changes in the gonadotrophin content of the ventral lobe were seen five days after OVX in June.     

Regional co-ordinator for haemophilia in domiciliary practice.

The North-east Thames Region has appointed a nursing sister to co-ordinate the organisation of care for haemophiliacs in the region. As a result of the appointment, facilities for home treatment have expanded rapidly. Several associate centres providing care to haemophiliacs have been set up around the region in addition to the four main haemophilia centres, which are all in the south-west corner of the region. As well as providing support and supervision of patients on home treatment, the co-ordinator helps to place haemophiliac children in suitable schools, maintains the regional register of haemophiliacs, and has a more general role in ensuring that services are available where they are needed throughout the region.     

Catchment areas in general practice and their relation to size and quality of practice and deprivation: a descriptive study in one London borough.

OBJECTIVE: To relate the sizes of general practice catchment areas in one London borough to list size, deprivation payments, medical staffing, and locally and nationally recognised measures of quality. DESIGN: Study of general practice catchment area maps. SETTING: London borough of Lambeth. SUBJECTS: 60 out of the 71 general practices in Lambeth. MAIN OUTCOME MEASURES: Practice catchment area size with corrections for numbers of doctors and patients. RESULTS: Catchment area size varied greatly between practices, showing an almost 150-fold difference between the largest and smallest practices. This size differential was even more marked when the size of the catchment area was corrected for the number of general practitioners in the practice, where a 300-fold difference was found. Substantial differences existed between practices in each of the four locally assigned quality bands. The weakest practices had catchment areas three times as large as those of the strongest practices. When corrected for medical staffing, the difference was eight times as great. A calculated measure of patient dispersion showed that the practice population of the strongest practices was four times as densely clustered as that of the weakest practices, whose patients were more widely geographically dispersed. CONCLUSIONS: Large variations exist in the size of catchment areas of inner city practices even when corrected for numbers of doctors and patients. These differences are associated with variations in quality of care.     

Metabolic Expenditures of Lunge Feeding Rorquals Across Scale: Implications for the Evolution of Filter Feeding and the Limits to Maximum Body Size

Bulk-filter feeding is an energetically efficient strategy for resource acquisition and assimilation, and facilitates the maintenance of extreme body size as exemplified by baleen whales (Mysticeti) and multiple lineages of bony and cartilaginous fishes. Among mysticetes, rorqual whales (Balaenopteridae) exhibit an intermittent ram filter feeding mode, lunge feeding, which requires the abandonment of body-streamlining in favor of a high-drag, mouth-open configuration aimed at engulfing a very large amount of prey-laden water. Particularly while lunge feeding on krill (the most widespread prey preference among rorquals), the effort required during engulfment involve short bouts of high-intensity muscle activity that demand high metabolic output. We used computational modeling together with morphological and kinematic data on humpback (Megaptera noveaangliae), fin (Balaenoptera physalus), blue (Balaenoptera musculus) and minke (Balaenoptera acutorostrata) whales to estimate engulfment power output in comparison with standard metrics of metabolic rate. The simulations reveal that engulfment metabolism increases across the full body size of the larger rorqual species to nearly 50 times the basal metabolic rate of terrestrial mammals of the same body mass. Moreover, they suggest that the metabolism of the largest body sizes runs with significant oxygen deficits during mouth opening, namely, 20% over maximum at the size of the largest blue whales, thus requiring significant contributions from anaerobic catabolism during a lunge and significant recovery after a lunge. Our analyses show that engulfment metabolism is also significantly lower for smaller adults, typically one-tenth to one-half . These results not only point to a physiological limit on maximum body size in this lineage, but also have major implications for the ontogeny of extant rorquals as well as the evolutionary pathways used by ancestral toothed whales to transition from hunting individual prey items to filter feeding on prey aggregations.