J. R. Busvine
Bio: J. R. Busvine is an academic researcher. The author has contributed to research in topics: Arthropod Vector. The author has an hindex of 1, co-authored 1 publications receiving 7 citations.
Topics: Arthropod Vector
01 Jan 1975
TL;DR: Unicellular cyanobacteria from the tropical North Atlantic and subtropical North Pacific share a common ancestry (16S rDNA) and that potential unicellular N2 fixers have diverged (nifH), and rates of fixation by bacterioplankton can be almost as high as those by the colonial N2-fixing marine cyanob bacteria Trichodesmium spp.
Abstract: N2-fixing proteobacteria (alpha and gamma) and unicellular cyanobacteria are common in both the tropical North Atlantic and Pacific oceans. In near-surface waters proteobacterial nifH transcripts were present during both night and day while unicellular cyanobacterial nifH transcripts were present during the nighttime only, suggesting separation of N2 fixation and photosynthesis by unicellular cyanobacteria. Phylogenetic relationships among unicellular cyanobacteria from both oceans were determined after sequencing of a conserved region of 16S ribosomal DNA (rDNA) of cyanobacteria, and results showed that they clustered together, regardless of the ocean of origin. However, sequencing of nifH transcripts of unicellular cyanobacteria from both oceans showed that they clustered separately. This suggests that unicellular cyanobacteria from the tropical North Atlantic and subtropical North Pacific share a common ancestry (16S rDNA) and that potential unicellular N2 fixers have diverged (nifH). N2 fixation rates for unicellular bacterioplankton (including small cyanobacteria) from both oceans were determined in situ according to the acetylene reduction and 15N2 protocols. The results showed that rates of fixation by bacterioplankton can be almost as high as those of fixation by the colonial N2-fixing marine cyanobacteria Trichodesmium spp. in the tropical North Atlantic but that rates are much lower in the subtropical North Pacific.
21 Jul 2010
TL;DR: Combining morphological and molecular data showed no congruence between the groups produced by the different methods although one well supported molecular grouping appeared to have a western Himalayan phytogeographical element.
Abstract: The 250 to 300 species of subgenus Hymenanthes are divided into 24 subsections that are contained within a single section, Ponticum. The subgenus as a whole has a clear identity and would appear to be a monophyletic group. Evidence includes three characters that appear to be synapomorphic. A number of the subsections are thought to represent natural groups others are considered to be assemblages that may or may not have evolutionary significance. Hybridisation occurs both within and between the subsections. Morphological, RAPD, PCR-RFLP and ITS sequence data was used to assess whether there was a phylogenetic structure within the subgenus that could form the basis of a sectional treatment. In the RAPD study difficulties were encountered in producing reproducible, scorable fingerprints and, in particular, in ascertaining the homology of different amplification products. A PCR-RFLP study of the ITS region failed to reveal sufficient polymorphic sites and a sequencing approach was therefore adopted. The ITS regions of 27 species from across the morphological range of diversity were sequenced but very little variation was encountered. There were a total of 27 variable base positions and of these 13 were autapomorphic for individual species leaving just 14 potentially informative characters. The final analysis, combining morphological and molecular data showed no congruence between the groups produced by the different methods although one well supported molecular grouping appeared to have a western Himalayan phytogeographical element. Whether the lack of ITS variation was due to the rapid evolution that is occurring in the group or the lack of breeding barriers or a combination of the two was debated. Random dominant marker methodologies such as RAPD appear inappropriate for use in the construction of hierarchical relationships. The results caste doubt on how large complex groups such as subgenus Hymenanthes may be adequately described without abandoning the hierarchical paradigm.
TL;DR: Bily regional differences in diameter of hair shaft and medullary presence were affirmed and continuous type medulla was predominant in all hairs, with a trend of percentage occurrence in descending order from the pubic, axilla, eyebrow, and scalp in both sexes.
Abstract: Context: Relatively scanty literature on autochthonic African Negroid hair morphology provokes research interest for anthropological, forensic, and cosmetic purposes. Aims: This study aimed to contribute basic morphological information on Ghanaian African hairs. Settings and Design: The study was done in selected second-cycle schools in Accra, Ghana, using convenient sampling. Subjects and Methods: Hairs were obtained by pluck method, from 30 males and 30 females aged 15–20 years. Ghanaian African autochthony was established if individuals had two generations of indigenous Ghanaian parentage. Scalp, eyebrow, axilla, and pubic hairs were image captured using a digital light microscope eyepiece connected to a computer. Diameters of hair strands were measured; types of the medulla and the form and shape of the hair roots were studied. Statistical Analysis Used: ANOVA test (SPSS Version 17.0) was used to compare the means of quantitative hair features among the sexes and the four regions of the body studied. Results: Pubic hair shaft was thickest (respective male and female diameters were 100.21 μm, 88.40 μm) and eyebrow hair was thinnest (53.97 and 46.69-μm diameters in males and females, respectively). Axillary and scalp hairs were the closest in diameters with 76.21 and 72.02 μm, respectively, in males and 73.07 and 71.15 μm, respectively, in females. Continuous type medulla was predominant in all hairs, with a trend of percentage occurrence in descending order from the pubic, axilla, eyebrow, and scalp in both sexes. Conclusions: Bodily regional differences in diameter of hair shaft and medullary presence were affirmed.
TL;DR: In this article, a Confocal Scanning Photoacoustic Microscopy (CSPAM) system was developed, in which PAS is combined with confocal scanning laser microscopy.
Abstract: vivo measurements of plant photosynthesis of intact undetached leaves. In this study, we have measured photosynthesis reaction using OPC and developed a Confocal Scanning Photoacoustic Microscopy (CSPAM) system, in which PAS is combined with confocal scanning laser microscopy. The system allows simultaneous measurement of acoustic signal and another signal such as fluorescence, and also gives twoand threedimensional intensity distributions of these signals, thereby giving twoand threedimensional information about photosynthetic activity of plants. key words: photoacoustic spectroscopy, photosynthesis, confocal
01 Jul 2012
TL;DR: In this article, the authors examined the relationship between zooplankton community dynamic and important biotic factors, such as predation and food availability, in Jakarta bay, from July to November 2009.
Abstract: The dynamics in zooplankton abundance were regulated by changes in water physical-chemical parameters and interaction with biotic factors. In this research we examined the relationship between zooplankton community dynamic and important biotic factors, such as predation and food availability, in Jakarta bay. Plankton samplings were done in 10 sampling stations in Jakarta bay, from July to November 2009. Zooplankton samples were collected using horizontal towing method with NORPAC plankton net (mesh size 300 μm). Salinity, water depth, water temperature, and water transparency were measured. Phytoplankton samples were also collected with the same method as zooplankton, using Kitahara plankton net (mesh size 80 μm). Zooplankton taxas were grouped into two groups, the prey and predatory zooplankton. The results showed that there were two different patterns in zooplankton groups dynamic i.e., the single and double peak. The abundance peak in most zooplankton groups, such as copepods, cirripeds, luciferids, and tunicates, were induced by the high food availability during the phytoplankton bloom in August. The high abundance of prey zooplankton groups in August was responded by the predatory zooplankton groups, resulting in high abundance of predatory zooplankton in adjacent month. The high abundance of ctenophores and chordates (fish larvae) were suggested as the main factor for the low abundance of other zooplankton in September. Physical and chemical factors were not the regulating factors due to the stability of those factors during this research period. Thus we concluded that food availability and predator-prey interaction were the main factors which regulate zooplankton community dynamics in Jakarta bay. Keywords: predator-prey interaction, zooplankton, abundance peak, food availability, phytoplankton bloom