Expression of the potato leafroll luteovirus coat protein gene in transgenic potato plants inhibits viral infection

Transgenic potato plants, cultivar Désirée, were produced that contained the coat protein gene of potato leafroll luteovirus (PLRV). The transformed potato plants expressed the PLRV coat protein (CP) RNA sequences but accumulation of coat protein in transgenic tissues could not be detected. Upon inoculation with PLRV, the PLRV CP RNA expressing potato plants showed a reduced rate of virus multiplication.     

Homology Requirements for Unequal Crossing over in Humans

To gain insight into mechanisms of unequal homologous recombination in vivo, genes generated by homologous unequal crossovers in the human beta-globin gene cluster were examined by nucleotide sequencing and hybridization experiments. The naturally occurring genes studied included one delta-beta Lepore-Baltimore fusion gene, one delta-beta Lepore-Hollandia fusion gene, 12 delta-beta Lepore-Boston genes, one A gamma-beta fusion Kenya gene, one A gamma-G gamma fusion (the central gene of a triplication) and one G gamma-A gamma fusion. A comparison of the nucleotide sequences of three Lepore-Boston genes indicates that they were derived from at least two independent homologous but unequal crossover events, although the crossovers occurred within the same 58-bp region. Nine additional Lepore-Boston genes from individuals of various ethnic origins were shown, by hybridization to specific oligonucleotide probes, to have been generated by a crossover in the same region as the sequenced genes. Evidence for gene conversion accompanying a homologous unequal crossover event was found in only one case (although some of the single nucleotide differences observed in other genes in this study may be related to the crossover events in ways that we do not presently understand). Thus, as judged by this limited sample, concurrent gene conversions are not commonly associated with homologous but unequal exchange in humans in vivo. Classification of the recombinant chromosomes by their polymorphic restriction sites in the beta-globin gene cluster indicated that the Lepore-Boston genes are found in at least six different haplotype backgrounds. Therefore the total number of independent examples in this study is at least 6, and at most 12. We have shown that in at least six cases of genes that have arisen by homologous but unequal crossing over in vivo, each event occurred in a relatively extensive region of uninterrupted identity between the parental genes. This preference cannot be explained by a mechanism whereby crossovers occur at random within misaligned related but not identical genes. In general, crossovers occur in regions that are among the largest available stretches of identity for a particular pair of mismatched genes. Our data are in agreement with those of other types of studies of homologous recombination, and support the idea that sequence identity, rather than general homology, is a critical factor in homologous recombination.     

Use of DNA hybridization values to construct three-dimensional models of fluorescent pseudomonad relationships

Three-dimensional models of the relationships among fluorescent pseudomonads were prepared from appropriately transformed percent DNA homology values. The transformation selected was f(x) = ( (1 - HOM/HOM)200, where HOM = fractional DNA homology and 200 is a scaling factor. Model accuracy was quite good as a plot of transformed DNA homology values versus model distances was essentially linear for homology values greater than 30%. The model suggested that bacterial strains within the fluorescent pseudomonads appear to be related in a three-dimensional continuum with no clear and easy "natural" demarcation into groups (i.e., species).     

The beta-delta crossover leading to the beta delta hybrid gene of hemoglobin P-Nilotic is located within 54 base-pairs of the 5' end of exon 2 or between codons 31 and 50

The crossover region of the beta delta hybrid gene of the hemoglobin variant Hb P-Nilotic was defined in detail through cloning and sequencing of appropriate DNA segments. The crossover must have occurred without loss of bases within a 54 base-pair stretch of DNA between bases 275 and 330 (or between amino acid residues 31 and 50), indicating that the exon 1 and IVS-1 originate from beta, and exon 2, IVS-2 and exon 3 from delta. The data support the speculation that the IVS-1, in contrast to IVS-2, has no effect on the expression of this hybrid gene.     

The detection of beta-globin gene mutations in beta-thalassemia using oligonucleotide probes and amplified DNA

DNA amplification combined with the use of synthetic oligonucleotide probes has become an important tool in the identification of base substitutions. We report the use of this DNA amplification technique for the detection of mutations in beta-thalassemia. A series of oligonucleotide primers are synthesized which span the beta-globin gene; one primer is complementary to the coding strand and the other to the non-coding strand. The primers are chosen so that there is little homology with other DNA segments, especially the delta gene. Each set of primers spans an area of the gene between 100 and 300 bp, while the suspected mutation point is located between these two primers. With the use of such a primer set, the beta-globin gene region is amplified by denaturation, annealing and DNA synthesis. The amplification cycle is repeated 25-30 times, using the Klenow fragment of DNA polymerase I. The resulting amplified DNA is hybridized with normal and synthetic deoxynucleotide probes using a standard dot-blot method. We have designed a set of primers and experimental conditions which should prove useful to diagnostic centers for detection of numerous beta-thalassemia mutations.     

Metabolic extraction of dopamine in the canine lungs

Pulmonary metabolism has been demonstrated to be one of the mechanisms of intrapulmonary removal of dopamine. After a bolus injection of [14C]dopamine into the caval vein of an anaesthetized dog a removal of [14C]-radioactivity into the extravascular space was accompanied by an intravascular alteration of the composition of the [14C]compounds during a single transpulmonary passage. A removal of 22% of [14C]-radioactivity out of the bloodstream, together with a metabolic conversion of the remaining [14C]dopamine within the bloodstream, resulted in a total pulmonary extraction of 22% + (0.78 x 18%) = 36%. This report gives a design for further investigation of the metabolic function of the lung sustained by a scheme for problem solving. Also perspectives for clinical application have been compiled.     

The link between vascular deterioration and branched chain amino acids in a population with high glycated haemoglobin: the SABPA study

Globally the prevalence of non-communicable diseases, such as hypertension and type 2 diabetes, are escalating. Metabolomic studies indicated that circulating branched chain amino acids (BCAAs) are associated with insulin resistance, coronary artery disease and increased risk for cardiovascular events. We aimed to extend the current understanding of the cardiovascular risk associated with BCAAs. We explored whether BCAAs are related to markers of cardiovascular disease in a bi-ethnic population and whether this relationship was influenced by chronic hyperglycaemia. We included 200 African and 209 Caucasian participants, and determined their ambulatory blood pressure and carotid intima-media thickness (cIMT). We analysed blood samples for glycated haemoglobin (HbA1c) and BCAAs. Participants were stratified into two groups according to their HbA1c value using the median cut-off value of 5.6 %. Ambulatory BP, cIMT and BCAAs were significantly higher (all p < 0.001) in the high HbA1c group. Single regression analyses indicated significant positive associations of ambulatory blood pressure and cIMT with BCAAs (all p < 0.05) in both the groups. These associations between ambulatory systolic blood pressure (SBP) (r = 0.16, p = 0.035) and cIMT (r = 0.22, p = 0.004) with BCAAs remained in the high HbA1c group after adjusting for age, gender, ethnicity and body mass index (BMI) and were confirmed in multiple regression analyses (ambulatory SBP: R ² = 0.17, β = 0.21, p = 0.005 and cIMT: R ² = 0.30, β = 0.19, p = 0.003). Our results demonstrate that BCAAs are independently related to ambulatory BP and cIMT in individuals with high HbA1c levels and suggest that potential cardiovascular deterioration accompany the rise in BCAAs in conditions of hyperglycaemia.     

Culture of the astaxanthin-producing green algaHaematococcus pluvialis 1. Effects of nutrients on growth and cell type

The freshwater green algaHaematococcus pluvialis (Strain Vischer 1923/2) grows best at high nitrate concentrations (about 0.5 to 1.0 g 1^–1 KNO₃), intermediate phosphate concentration (about 0.1 g 1^–1 K₂HPO₄) and over a wide range of Fe concentrations. Low nitrate or high phosphate induce the formation of reddish palmella cells and aplanospores. Mixotrophic growth with acetate improves growth rate and final cell yield, and also stimulates the formation of the astaxanthin-containing palmella cells and aplanospores.H. pluvialis cannot grow above about 28 °C, or above a salinity of approximately 1% w/v NaCl. An increase in temperature or the addition of NaCl also stimulates the formation of palmella cells and aplanospores.     

Phylogenetic study of the Nemaliales (Rhodophyta) based on large-subunit ribosomal DNA sequences supports segregation of the Scinaiaceae fam. nov. and resurrection of Dichotomaria Lamarck

Gene sequence data have been newly obtained for 18 species in 13 genera of the order Nemaliales (Rhodophyta), allowing for the first time a relatively comprehensive molecular phylogenetic appraisal of the order. The phylogenetic trees generated from these data support the recognition of three families: (i) the Liagoraceae as presently constituted; (ii) a reduced Galaxauraceae including Actinotrichia, Galaxaura (sensu lato), and Tricleocarpa; and (iii) a new family, Scinaiaceae, segregated from the Galaxauraceae and including the genera Scinaia, Gloiophloea, Nothogenia, and probably Whidbeyella. The four genera of the Scinaiaceae differ from the newly circumscribed Galaxauraceae in being uncalcified, and having heteromorphic life histories in which the tetrasporophyte is much reduced and filamentous or crustose. This type of life history is found in only Tricleocarpa of the Galaxauraceae. The results also show Galaxaura to be para/polyphyletic if Actinotrichia and Tricleocarpa are recognized. To remedy this, the Galaxaura marginata species complex, Galaxaura diesingiana, and Galaxaura obtusata are removed from the genus and placed in the resurrected Dichotomaria Lamarck. Galaxaura marginata, presently thought to be wide‐ranging and morphologically variable, is shown to comprise several species. As a consequence, Galaxaura tenera Kjellman and Brachycladia australis Sonder are removed from the synonymy of G. marginata and restored as independent species in Dichotomaria for South African and Australian isolates, respectively. The Liagoraceae is shown to encompass genera previously placed in the segregate families Nemaliaceae and Dermonemataceae, and the value of the reproductive characters used to define those taxa is discussed.