A Model of the Effect of Pseudothecia on Genetic Recombination and Epidemic Development in Populations of Mycosphaerella graminicola.

ABSTRACT It is generally agreed that ascospores are the origin of primary infections for the disease septoria tritici blotch of wheat caused by the fungus Mycosphaerella graminicola (anamorph Septoria tritici). The epidemic during the growing season was previously ascribed to the asexual pycni-diospores dispersed over short distances by rain splash, but recent observations suggest that the airborne ascospores also may play a role. As a consequence, the composition of the pathogen population over the growing season may change through genetic recombination. In an attempt to resolve the relative importance of the two spore types to the epidemic over the growing season, a model simulating disease caused by both types of spores was constructed and analyzed. The conclusion from the analysis of this model is that sexual recombination will affect the genetic composition of the population during a growing season. A considerable proportion of spores released at the end of the growing season may be sexual descendants of the initial population. However, ascospores are unlikely to affect the severity of the epidemic during the growing season. This is due to the much longer latent period for pseudothecia compared with pycnidia, resulting in ascospores being produced too late to influence the epidemic.

Preferential exclusion of hybrids in mixed pollinations between oilseed rape (Brassica napus) and weedy B. campestris (Brassicaceae).

In most experimental hybridizations between oilseed rape (Brassica napus) and weedy B. campestris, either intra- or interspecific pollen has been applied to individual flowers. Under field conditions, however, stigmas will often receive a mixture of the two types of pollen, thereby allowing for competition between male gametophytes and/or seeds within pods. To test whether competition influences the success of hybridization, pollen from the two species was mixed in different proportions and applied to stigmas of both species. The resulting seeds were scored for paternity by isozyme and randomly amplified polymorphic DNA analysis. Using data on the proportion of fully developed seeds and the proportion of these seeds that were hybrids, a statistical model was constructed to estimate the fitness of conspecific and heterospecific pollen and the survival of conspecific and heterospecific zygotes to seeds. B. campestris pollen in B. napus styles had a significantly lower fitness than the conspecific pollen, whereas no difference between pollen types was found in B. campestris styles. Hybrid zygotes survived to significantly lower proportions than conspecific zygotes in both species, with the lowest survival of hybrid zygotes in B. napus pods. This is in contrast to the higher survival of hybrid seeds in B. napus than in B. campestris pods when pollinations are made with pure pollen. Altogether, the likelihood of a foreign pollen grain producing a seed was much lower on B. napus than on B. campestris. In addition, pods on B. napus developed to a lower extent the more heterospecific pollen was in the mix, whereas this had no effect on B. campestris.

Biochemical identification of the bovine blood group M' antigen as a major histocompatibility complex class I-like molecule.

Absorption and elution experiments showed that it was impossible to separate antibodies against blood group factor M' from antibodies against bovine lymphocyte antigen (BoLA) A16 in an antiserum showing haemolytic activity against M' as well as lymphocytotoxic activity against BoLA-A16. To elucidate the structural relationship between BoLA-A16 and blood group antigen M', immunoprecipitation experiments on red and white cell lysates isolated from M'-A16 positive and negative cattle were carried out. These results showed that M(r) 44,000 and M(r) 12000 polypeptides can be precipitated from both red and white cells isolated from M'-A16 positive animals, whereas no bands were seen in M'-A16 negative animals in precipitations with the same antibody. Precipitation with a crossreacting human beta 2-microglobulin (beta 2-m) specific antibody confirmed a class-I-like structure associated with beta 2-m on M' positive red cells and the absence of such a structure on M' negative red cells. Sequential precipitations gave analogous results. Proteolytic degradation by papain and V8 protease did not reveal any substantial difference between red and white M'-A16 positive cells, but a slight difference in the pI of the immunoprecipitable components of red and white cells was observed. All together, this indicates that either the blood group antigen M' is the BoLA-A16 class I antigen or M' and BoLA-A16 are two different class I polypeptides with the same relative mass, sharing identical epitopes and both associated with beta 2-m. Comparable results were obtained with M1 and BoLA-A24.

Analysis of associations between major histocompatibility complex (BoLA) class I haplotypes and subclinical mastitis of dairy cows.

The associations between BoLA class I haplotypes and subclinical mastitis were investigated using information on 333 cows from three different breeds and crossbreeds from 14 dairy herds in Denmark. Somatic cell count and bacteriological status were used as markers for subclinical mastitis. Associations between BoLA class I haplotypes and IMI status were also determined. The association between BoLA class I haplotypes and subclinical mastitis was weak. The A10(W50), A11, A12(A30), A16, A19(A6), A21, A26, and A31(A30) alleles were associated with different markers of subclinical mastitis. Susceptibility or resistance to the two bacteria categories was associated with different alleles. This study indicated that BoLA antigens may be involved in resistance to mastitis and that resistance may be specific for a particular pathogen.

Iron deficiency and iron overload in Swedish male adolescents.

OBJECTIVES: The present study was undertaken to confirm or reject recent findings indicating a high prevalence of iron deficiency in Swedish male adolescents; a second aim was to study the prevalence of genetic iron overload. DESIGN: The diagnostic criteria were: anaemia: Hb < 130 g L-1 (a): iron deficiency: serum ferritin (SF) < 12 micrograms L-1 + transferrin saturation (TS) < 16% (b): iron deficiency anaemia a + b. Iron overload: SF (90th percentile) + TS (90th percentile) in repeat tests. SETTING: Central Sweden. SUBJECTS: A total 3975 men aged 18 years studied on enrollment into military service. RESULTS: Serum ferritin averaged 36.8 micrograms L-1. Anaemia was present in 0.5%, iron deficiency anaemia in 0.17% and iron deficiency in 0.4%. If iron deficiency is defined as SF < 16 micrograms L-1, as was recently suggested, the prevalence would be 2.8%. Such a cut-off value would include 73% normal people (false positives). Iron overload had the same prevalence as iron deficiency, 0.4%. CONCLUSIONS: Iron stores, as measured by serum ferritin, are small in young men studied at the end of their growth spurt. However, iron deficiency is rare. Therefore, the present study has not been able to confirm the high prevalence of iron deficiency recently reported. A prevalence of genetic haemochromatosis of 0.4%, confirms earlier findings and would mean that 12.6% of the population are heterozygotic carriers of the iron-loading genes. These findings give no support for a proposed, more effective iron-enrichment of food. It is not needed and can be harmful.

The effects of wound infiltration with bupivacaine versus saline on postoperative pain and opioid requirements after herniorrhaphy.

In a prospective, double-blind, placebo-controlled study, twenty-eight healthy, male patients, aged 20-69 years, scheduled for unilateral elective inguinal herniorrhaphy ad modum Bassini were randomized to receive postoperative infiltration of the surgical wound with either bupivacaine 0.25%, or isotonic saline. General anaesthesia was induced with thiopentone 3-5 mg.kg-1 and alfentanyl 10 micrograms.kg-1, and maintained with alfentanyl 5 micrograms.kg-1 15 min and N2O/O2. After herniorrhaphy, the internal fascia was infiltrated with bupivacaine 0.25% or saline, 10 ml. After closure of the external fascia, the subcutaneous tissue was infiltrated with bupivacaine 0.25% or saline, 15 ml on both sides of the surgical wound. Pain at rest, during mobilisation and during cough was significantly decreased in patients receiving bupivacaine compared to placebo. Median time to first request for morphine was increased from 25 min to 135 min, and the consumption of supplementary morphine during the 24 h study period reduced from four to two doses of 0.1 mg.kg-1 iv or 0.125 mg.kg-1 im, in patients who received bupivacaine compared to placebo.

Genetic diversity among wild and cultivated barley as revealed by RFLP.

Genetic variability of cultivated and wild barley, Hordeum vulgare ssp. vulgare and spontaneum, respectively, was assessed by RFLP analysis. The material consisted of 13 European varietes, single-plant offspring lines of eight land races from Ethiopia and Nepal, and five accessions of ssp. spontaneum from Israel, Iran and Turkey. Seventeen out of twenty-one studied cDNA and gDNA probes distributed across all seven barley chromosomes revealed polymorphism when DNA was digested with one of four restriction enzymes. A tree based on genetic distances using frequencies of RFLP banding patterns was estimated and the barley lines clustered into five groups reflecting geographical origin. The geographical groups of land-race lines showed less intragroup variation than the geographical groups of spontaneum lines. The group of European varieties, representing large variation in agronomic traits, showed an intermediate level. The proportion of gene diversity residing among geographical groups (FST) varied from 0.19 to 0.94 (average 0.54) per RFLP pattern, indicating large diversification between geographical groups.

[Malignant melanoma of the penis]. / Malignt melanom på penis.

Malignant melanoma of the penis is rare, and accounts for only a small percentage of penile carcinomas. The prognosis is poor, and most patients die within three years due to distant metastases. Awareness of the possibility of malignant melanoma occurring at this uncommon site is an important factor in early diagnosis and consequent improvement of survival. The case report of a man with malignant melanoma of the penis is presented.

One-dimensional isoelectric focusing and immunoblotting of bovine major histocompatibility complex (BoLA) class I molecules and correlation with class I serology.

One-dimensional isoelectric focusing followed by immunoblotting and development of the immunoblots with the monoclonal antibody HC-10, raised against denatured HLA class I heavy chains, was used to demonstrate biochemical variation in cattle MHC (BoLA) class I molecules. The bands obtained correlated well with BoLA-A specificities. Two or three bands were identified for the specificities w7, w8, w16, w18, w21, cph43 and cph49, whereas no bands were observed for the specificity w2. Two serologically indistinguishable subtypes of specificity w18 were identified.

Estimating relative fitness in asexually reproducing plant pathogen populations.

A mathematical model is presented and analysed to find the conditions under which changes in gene frequencies can be used in asexually reproducing populations for estimating fitness of single genes, for example, for estimating the fitnesses of unnecessary virulence genes relative to their corresponding avirulence genes. It is concluded that the underlying distribution of relative fitness of clones (genotypes) has to be unimodal and that many populations consisting of a mixture of distinguishable clones then provide the best experimental data for estimating relative fitness of single genes. An improved statistical test procedure, i.e. generalized logistic regression, is suggested for analysing changes in gene frequencies in population experiments with a mixture of distinguishable clones. A population study of Erysiphe graminis f.sp. hordei (Klug-Andersen 1980) provides data to illustrate the procedure in the case where the population consists of a large number of genotypes. A bimodal distribution of "genotypes" possessing the virulence gene is indicated here.