Assessment of Red Core Resistance of Strawberry Using Enzyme-Linked Immunosorbent Assay (ELISA)

There was a strong correlation between measurements of red core disease of strawberry, assessed as percentage lengths of the adventitious roots with red steles, and ELISA values obtained from the same root systems using a polyclonal antiserum raised to Phytophthora fragariae. ELISA grouped twelve host cultivar/pathogen isolate combinations into three categories, highly resistant, partially resistant and susceptible, which agreed with disease incidence after inoculation.     

Altered Mitochondrial Respiration in a Chromosomal Mutant of Neurospora crassa

A mutant of Neurospora crassa (cni-1) has been isolated that has two pathways of mitochondrial respiration. One pathway is sensitive to cyanide and antimycin A, the other is sensitive only to salicyl hydroxamic acid. Respiration can proceed through either pathway and both pathways together in this mutant account for greater than 90% of all mitochondrial respiration. The cni-1 mutation segregates as a nuclear gene in crosses to other strains of Neurospora. Absorption spectra of isolated mitochondria from cni-1 show typical b- and c-type cytochromes but the absorption peaks corresponding to cytochrome aa(3) are not detectable. Extraction of soluble cytochrome c-546 from these mitochondria followed by reduction with ascorbate reveals a new absorption peak at 426 nm that is not present in wild-type mitochondria. This peak may be due to an altered cytochrome oxidase with abnormal spectral properties. Mitochondria from cni-1 have elevated levels of succinate-cytochrome c reductase but reduced levels of nicotinamide adenine dinucleotide reduced form cytochrome c reductase and of cyanide- and azide-sensitive cytochrome c oxidase. These studies suggest that the cni-1 mutation results in the abnormal assembly of cytochrome c oxidase so that the typical cytochrome aa(3) spectrum is lost and the enzyme activity is reduced. As a consequence of this alteration, a cyanide-insensitive respiratory pathway is elaborated by these mitochondria which may serve to stimulate adenosine 5'-triphosphate production via substrate level phosphorylation by glycolysis and the Krebs cycle.     

Evolution of modern birds revealed by mitogenomics: timing the radiation and origin of major orders

Mitochondrial (mt) genes and genomes are among the major sources of data for evolutionary studies in birds. This places mitogenomic studies in birds at the core of intense debates in avian evolutionary biology. Indeed, complete mt genomes are actively been used to unveil the phylogenetic relationships among major orders, whereas single genes (e.g., cytochrome c oxidase I [COX1]) are considered standard for species identification and defining species boundaries (DNA barcoding). In this investigation, we study the time of origin and evolutionary relationships among Neoaves orders using complete mt genomes. First, we were able to solve polytomies previously observed at the deep nodes of the Neoaves phylogeny by analyzing 80 mt genomes, including 17 new sequences reported in this investigation. As an example, we found evidence indicating that columbiforms and charadriforms are sister groups. Overall, our analyses indicate that by improving the taxonomic sampling, complete mt genomes can solve the evolutionary relationships among major bird groups. Second, we used our phylogenetic hypotheses to estimate the time of origin of major avian orders as a way to test if their diversification took place prior to the Cretaceous/Tertiary (K/T) boundary. Such timetrees were estimated using several molecular dating approaches and conservative calibration points. Whereas we found time estimates slightly younger than those reported by others, most of the major orders originated prior to the K/T boundary. Finally, we used our timetrees to estimate the rate of evolution of each mt gene. We found great variation on the mutation rates among mt genes and within different bird groups. COX1 was the gene with less variation among Neoaves orders and the one with the least amount of rate heterogeneity across lineages. Such findings support the choice of COX 1 among mt genes as target for developing DNA barcoding approaches in birds.     

Carotid endarterectomy: survival rates of 227 patients.

From March 1963 to March 1974, 227 patients with carotid stenosis underwent unilateral or bilateral carotid endarterectomy at l''Hôpital de l''Enfant-Jésus in Québec. Survival during the first 7 years after operation was analysed by life-table methods based on full intervals. The observed probability of death in this group was significantly higher than the probability expected in the general population, by 6.8% in the 1st year and 3.9% in the 2nd year. In the next 3 years the differences were much smaller (0.5, 0.9 and 1.4%). The major causes of death were myocardial infarction and stroke. Women fared somewhat better than men after the 1st year of follow-up. Unexpectedly, patients who underwent unilateral endarterectomy had lower survival rates in each of the first 5 years after operation than patients who underwent staged bilateral operations, whether survival was measured from the date of the first or the second operation.     

Cotton roots and vitamin-requiring and amino acid-requiring bacteria

Summary The rhizosphere effects of diploid and amphidiploid strains of cotton in black cotton soils have been investigated with reference to vitamin-requiring bacteria and amino acid-requiring bacteria. Influence of cotton roots on amino acid-requiring bacteria was found to be greater than on vitamin-requiring bacteria. The rhizosphere effects of diploid strains were greater than those of amphidiploid strains. The effects were also influenced by the initial proportions of these bacterial groups in the two soils. The rhizosphere effects of inoculated plants were lower than the respective healthy controls; but those of apparently healthy (disease escapes) diploid plants and those of inoculated amphidiploid plants in PLD soil (wilt-sick) were strikingly higher than the healthy controls. Differences in the rhizosphere effects between diploid and amphidiploid plants could be correlated with the amino acid and vitamin exudations by roots of these strains, but not with reference to soil types.Part of Doctoral Thesis, University of Madras.     

Fungi intercepted from abroad

In a previous paper fungi intercepted on plant consignments imported from Afghanistan were described. The present paper gives an account of some more fungi that have been intercepted from time to time on plants and plant material imported from different countries.