A quartet pollen phenotype identified in a population of Brassica interspecific hybrids shows incomplete penetrance and variable response to temperature.

Quartet pollen, where pollen grains remain attached to each other post-meiosis, is useful for tetrad analysis, crossover assessment and centromere mapping. We observed the quartet pollen phenotype for the first time in the agriculturally significant Brassica genus, in an experimental population of allohexaploid Brassica hybrids derived from the cross (Brassica napus × B. carinata) × B. juncea followed by two self-pollination generations. Quartet pollen production was assessed in 144 genotypes under glasshouse conditions, following which a set of 16 genotypes were selected to further investigate the effect of environment (warm: 25 °C and cold: 10 °C temperatures) on quartet pollen production in growth cabinets. Under glasshouse phenotyping conditions, only 92 out of 144 genotypes produced enough pollen to score: of these, 30 did not produce any observable quartet pollen, while 62 genotypes produced quartet pollen at varying frequencies. Quartet pollen production appeared quantitative and did not clearly fall into phenotypic or qualitative categories indicative of major gene expression. No consistent effect of temperature on quartet pollen production was identified, with some genotypes producing more and some producing less quartet pollen under different temperature treatments. The genetic heterogeneity and frequent pollen infertility of this population prevents strong conclusions being made. However, it is clear that the quartet phenotype in this Brassica population does not show complete penetrance and shows variable (likely genotype-specific) response to temperature stress. In future, identification of quartet phenotypes in Brassica would perhaps best be carried out via screening of diploid (e.g. B. rapa) TILLING populations.

Oilseed rape: learning about ancient and recent polyploid evolution from a recent crop species.

Oilseed rape (Brassica napus) is one of our youngest crop species, arising several times under cultivation in the last few thousand years and completely unknown in the wild. Oilseed rape originated from hybridisation events between progenitor diploid species B. rapa and B. oleracea, both important vegetable species. The diploid progenitors are also ancient polyploids, with remnants of two previous polyploidisation events evident in the triplicated genome structure. This history of polyploid evolution and human agricultural selection makes B. napus an excellent model with which to investigate processes of genomic evolution and selection in polyploid crops. The ease of de novo interspecific hybridisation, responsiveness to tissue culture, and the close relationship of oilseed rape to the model plant Arabidopsis thaliana, coupled with the recent availability of reference genome sequences and suites of molecular cytogenetic and high-throughput genotyping tools, allow detailed dissection of genetic, genomic and phenotypic interactions in this crop. In this review we discuss the past and present uses of B. napus as a model for polyploid speciation and evolution in crop species, along with current and developing analysis tools and resources. We further outline unanswered questions that may now be tractable to investigation.

Transposon variation by order during allopolyploidisation between Brassica oleracea and Brassica rapa.

Although many studies have shown that transposable element (TE) activation is induced by hybridisation and polyploidisation in plants, much less is known on how different types of TE respond to hybridisation, and the impact of TE-associated sequences on gene function. We investigated the frequency and regularity of putative transposon activation for different types of TE, and determined the impact of TE-associated sequence variation on the genome during allopolyploidisation. We designed different types of TE primers and adopted the Inter-Retrotransposon Amplified Polymorphism (IRAP) method to detect variation in TE-associated sequences during the process of allopolyploidisation between Brassica rapa (AA) and Brassica oleracea (CC), and in successive generations of self-pollinated progeny. In addition, fragments with TE insertions were used to perform Blast2GO analysis to characterise the putative functions of the fragments with TE insertions. Ninety-two primers amplifying 548 loci were used to detect variation in sequences associated with four different orders of TE sequences. TEs could be classed in ascending frequency into LTR-REs, TIRs, LINEs, SINEs and unknown TEs. The frequency of novel variation (putative activation) detected for the four orders of TEs was highest from the F1 to F2 generations, and lowest from the F2 to F3 generations. Functional annotation of sequences with TE insertions showed that genes with TE insertions were mainly involved in metabolic processes and binding, and preferentially functioned in organelles. TE variation in our study severely disturbed the genetic compositions of the different generations, resulting in inconsistencies in genetic clustering. Different types of TE showed different patterns of variation during the process of allopolyploidisation.

Primary structure of phycocyanin from the unicellular rhodophyte Cyanidium caldarium. I. Complete amino acid sequence of the alpha subunit.

The complete amino acid sequence of the alpha subunit of phycocyanin from the unicellular rhodophyte Cyanidium caldarium has been determined by automated sequential degradation of cyanogen bromide peptides, tryptic peptides derived from protein chemically modified with 1,2-cyclohexanedione or citraconic anhydride, and a peptide obtained after cleavage of the protein at the single tryptophan residue. The alpha subunit contains 162 amino acids and methionine and serine are the NH2- and carboxyl-terminal amino acids, respectively. The calculated molecular weight of the protein, based on the amino acid sequence, is 18,303, in good agreement with the value of 17,500 +/- 500, obtained by electrophoresis on calibrated sodium dodecyl sulfate-polyacrylamide gels. One phycocyanobilin chromophore is attached to the alpha subunit at residue 84 by a cysteinyl thioether linkage. A second cysteine (residue 98) is present but is not linked to phycocyanobilin. The amino acid sequence of the alpha subunit of phycocyanin from C. caldarium is the first complete amino acid sequence of a phycobiliprotein from a eukaryotic alga. Extensive homology occurs between the alpha subunit of phycocyanin from C. caldarium and from two prokaryotic cyanobacteria, and the significance of this is discussed.

Primary structure of phycocyanin from the unicellular rhodophyte Cyanidium caldarium. II. Complete amino acid sequence of the beta subunit.

The complete amino acid sequence of the beta subunit of phycocyanin from the unicellular rhodophyte Cyanidium caldarium, has been determined by automated sequential degradation of cyanogen bromide, tryptic, and Staphylococcus aureus V8 protease peptides. The beta subunit contains 172 amino acids with methionine and glutamine the NH2- and carboxyl-terminal amino acids, respectively. The calculated molecular weight of the protein, based on the sequence, is 19,572. Two phycocyanobilin chromophores are covalently attached by cysteinyl thioether linkages to residues 82 and 153. A third cystine (residue 109) occurs in the beta subunit, but it is not attached to phycocyanobilin. Comparison of the complete amino acid sequence of the beta subunit of C. caldarium phycocyanin with the sequences of the phycocyanin beta subunits from two cyanobacteria, shows that the sequence homology previously noted at the NH2 terminus of phycobiliproteins from distantly related organisms extends along the entire polypeptide chain. The amino acid sequences of the alpha and beta subunits of C. caldarium phycocyanin are also similar, and by proper alignment of the sequences it can be shown that the beta subunit contains a 12-residue insertion where the second phycocyanobilin chromophore is covalently attached. A matrix comparing the alpha and beta subunits of phycobiliproteins for which the complete sequences are known has been determined, and based on these data, a scheme is proposed for evolution of the family of phycobiliproteins in living cyanobacteria and red algae from a protein precursor which gave rise initially to a beta-type allophycocyanin subunit.

Defective cortisol binding globulin affinity in association with adrenal hyperfunction: a case report.

A patient with an apparent abnormality of cortisol binding globulin (CBG) is reported. Investigations showed that while the plasma CBG binding capacity (equivalent to the plasma CBG concentration) was normal, the binding affinity was reduced by a factor of four. The significance of this observation is discussed with regard to its possible role in the development of the adrenocortical hyperfunction also seen in this patient.

Experience with human growth hormone in Great Britain: the report of the MRC Working Party.

The Working Party on human growth hormone (hGH) has during the past decade developed a system for the evaluation and treatment of patients suffering from hGH lack. Today there are nineteen measurement centres in the United Kingdom at which patients are assessed and where the effects of therapy are monitored. The current supply of hGH, which is prepared from pituitary glands collected by pathologists in the National Health Service, is just enough to meet demand, but research conducted on behalf of the Working Party suggests that hGH deficiency is more common than has been thought and that the prevalence may be as high as one in 10 000. If, as is hoped, patients are diagnosed younger and more patients with partial deficiency are recognized, demand may soon outstrip supply. Work is in progress to define better methods of hGH production and optimal dose regimens, both of which will help to minimize the problem of supply and demand. A few children have anti-hGH antibodies, which block growth as a result of treatment. Improved hGH production techniques may result in a less antigenic product and the resolution of this problem. Many of the Working Party's activities began as research and have evolved into service. Because of this shift in emphasis, and although much research is still to be done, responsibility for provision of treatment with hGH transferred from the Medical Research Council to the Department of Health and Social Security in July 1977.

Mineralocorticoid replacement in Addison's disease.

Eight patients with treated Addison's disease were studied whilst receiving different doses of fludrocortisone together with a constant intake of glucocorticoid. Plasma renin activity (PRA), blood pressure, pulse rate and plasma potassium and urea concentrations were measured after 2-week periods on each dose. In two patients, PRA measurements indicated that mineralocorticoid replacement therapy had been inadequate. In four others, PRA remained normal throughout the study, even after fludrocortisone had been discontinued, suggesting that the drug was unnecessary for the maintenance of normal sodium balance in these patients. Asymptomatic fludrocortisone overdosage was indicated by a low plasma potassium concentration, but not by PRA measurements which failed in this study to distinguish between adequate and excessive mineralocorticoid replacement.

Lipodystrophy with hyperlipidaemia: the role of insulin in very low density lipoprotein over-synthesis.

A patient with partial lipodystrophy is described in whom hypertriglyceridaemia was accompanied by marked hyperinsulinaemia. The hyperlipidaemia was due to increased plasma levels of very low density lipoprotein (VLDL). Kinetic studies, performed after injection of autologous radioiodinated VLDL, indicated that the raised VLDL levels were associated with over-production of this lipoprotein. Administration of diazoxide led to a substantial fall in serum insulin levels, accompanied by reduction in VLDL production and in serum triglyceride concentration. The possible role of insulin in inducing hyperlipidaemia by causing over-production of VLDL is discussed.

Male pseudohermaphroditism due to partial end-organ insensitivity to androgens.

A 46XY individual with incomplete male pseudohermaphroditism was studied. The phenotype was distinctive, with a masculine habitus despite a small phallus, gynaecomastia and diminished virilization. Plasma levels of testosterone, oestrogens, gonadotrophins and sex-hormone binding globulin were elevated. It is proposed that this syndrome is a variant of Type I incomplete male pseudohermaphroditism.

Patterns of antipsychotic drug use in four Southeastern state hospitals.

The drug prescriptions of patients in the four mental hospitals of a state were obtained as of a specific date and subjected to various analyses. The results disclose a high frequency of antiparkinson drug orders (41.5% of the patients), their relationship to polypharmacy (30% of the antipsychotic drug prescriptions were for two or more to be administered simultaneously), the direct relationship between the antipsychotic dose level and antiparkinson drug and PRN orders and the incidence of multiple dose schedules (75%). Also other prescription practices which have received little or no attention are described and discussed.

Long-term treatment of acromegaly with bromocriptine.

Seventy-three patients with active acromegaly were treated for three to 25 months with bromocriptine 10-60 mg/day. Seventy-one patients showed symptomatic and objective clinical improvement. This included reduction in excessive sweating, hand and foot size, and the number of headaches; improved facial appearance; and increased energy and libido. Abnormal visual fields became normal in two patients, one of whom had concomitant radiotherapy. Mean circulating growth hormone levels, obtained by averaging serial samples through the day, fell by more than 7 microng/l or became undetectable in 58 patients (79%) but did not reach normal values: only 15 patients had mean levels on treatment of 5 microng/l or less. Twenty-three patients were diabetic before treatment, and glucose tolerance became normal in 15 and improved in a further five. Provided the drug was started slowly side effects were minor when compared with the considerable clinical benefit obtained.