NSIS Volume 39 - Part 1
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Item Open Access Table of contents (v. 39, p. 1)(Dalhousie Printing Centre, 1990-03) Nova Scotian Institute of ScienceItem Open Access Lytic effects of 3-(3'-isocyanocyclopent-2'-enylidene) propionic acid on the cellulolytic rumen bacteria Fibrobacter succinogenes and Ruminococcus flavefaciens.(Dalhousie Printing Centre, 1990-03) Liss, S.N.; Jones, G. A.3-(3' -lsocyanocyclopent-2' -enylidene) propionic add (ICEP), a metabolite of Trichoderma hamatum, depressed the specific growth rate of exponential phase cultures of Fibrobacter succinogenes S65 and Ruminococcus flavefaciens C94 at concentrations up to 4.5 µg. mL-1 At 5 to 20 µg mL-1 depression of growth rate was followed by cell lysis. F. succinogenes was more susceptible to these effects than R. flavefaciens. The divalent cations Ca2+, Fe2+, Mg2+ and Mn2+ reduced the specific rate of lysis in cultures of F. succinogenes treated with ICEP but only Fe2+ showed a similar effect in R. flavefaciens cultures. When cells of either species were removed from contact with ICEP their capacity to resume growth depended on the duration of prior contact with the compound. ICEP showed no mutagenic activity in the replicative killing bacterial test.Item Open Access Taxonomic considerations of the genus Rhodophysema and the Rhodophysemataceae fam. nov. (Rhodophyta, Florideophycidae).(Dalhousie Printing Centre, 1990-03) Saunders, G. W.; McLachlan, J. L.Recent investigations of Rhodophysema, together with a literature review of the Acrochaetiales Palmariales complex, indicate that the genus Rhodophysema is not closely allied either with the Acrochaetiaceae or the Palmariaceae. Accordingly, a new family, Rhodophysemataceae, is proposed. In this treatment Rhodophysemataceae is differentiated from Acrochaetiaceae by the absence of a carposporophyte and monosporangia, presence of a unique sporangial stalk cell integral lathe sexual cycle and an abundance of cellular fusions. Rhodophysemataceae is separated from Palmariaceae by the occurrence of B-phycoerythrin I, presence of Rhodophysema-like tetrasporangia and heteromorphic sexual life histories. To date the placement of Rhodophysema in the Acrochaetiales or Palmariales has been based either on vegetative morphology and phycoerythrin type oron interpretations of the e\lOlution of the tetrasporangium and life-history type. Further evidence will be required to resolve the ordinal position of this new family. We, therefore, leave Rhodophysemataceae provisionally in the Palmariales while recognizing its uncertain taxonomic position within the Acrochaetiales-Palmariales complex. The Rhodophysemataceae may indeed warrant ordinal status as new taxonomic criteria become established. The genera Coriophyllum, Halosacciocolax, Pseudorhododiscus and Rhodophysemopsis are also discussed with respect to their taxonomic placement in the Acrochaetiales-Palmariales complex.Item Open Access Estimates of the numbers and areas of acidic lakes in Nova Scotia.(Dalhousie Printing Centre, 1990-03) Underwood, J. K.; Schwartz, P. Y.There are 6674 lakes larger than 1 hectare in Nova Scotia covering an area of 2255 km2. Geological and pH isopleth maps were consulted to estimate acidified and acid sensitive lakes. Assuming that granitic or metamorphic bedrock only very slowly produce add neutralizing ions, we estimate that 78% of the lakes (65% of lake area) would, in the absence of moderating influences of surficial geology and marine aerosols, be susceptible to acidification. When all sources of acid neutralizing capacity are indirectly considered via examination of pH isopleths drawn from lake chemistry, we estimate that 16% of the lakes (26% of lake area) have zero alkalinity. and that 69% of the lakes (80% of lake area) have < 50 µeq L-1 alkalinity.Item Open Access A survey of Infestation of crops by Striga spp in Benin, Nigeria and Togo(Dalhousie Printing Centre, 1990-03) Parkinson, V. O.The incidence of Striga spp. on agricultural crops in Benin, Nigeria and Togo between latitudes 4° N and 13° 30' N was surveyed in 1964 and 1965. The survey covered 463 fields in Nigeria, 112 in Benin and 55 in Togo. It was found that the Sfriga spp. responsible for significant commercial losses were S. hermonthica, S. asiatica, and S. aspera. In Nigeria S. hermonthica and S. aspera were frequently responsible for 100% loss of the crop. In the maize growing areas of Southern Benin and Togo the crop was mainly infested with S. asiatica. S. aspera is recorded on lowland Oryza sativa for the first time. Evidence is presented for the growth of S. hermonthica on Arachis hypogea.