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1.
The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
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2.
Annexin IV (endonexin) has been purified from chicken liver and crystallized by the vapour diffusion method. Crystals which diffract to at least 2.2 A have been obtained. They belong to space group R3 and have unit cell dimensions of a = b = 99.4 A, c = 96.2 A, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees. There is one molecule of 32,500 Da per asymmetric unit. 相似文献
3.
Changes in Acetylcholinesterase Molecular Forms During the Embryonic Development of Torpedo marmorata 总被引:1,自引:0,他引:1
Abstract: Multiple molecular forms of acetylcholinesterase from electric organ and electric lobe of Torpedo marmorata were examined at various developmental stages by sucrose density sedimentation. Four major forms were characterized by their apparent sedimentation coefficients of 6 S, 11 S, 13 S, and 17 S. Embryonic lobe possessed at early stages predominantly the 11 S form. With maturation the 17 S form became the most abundant. The early embryonic stages of the electric organ were characterized by predominating amounts of 6 S and 11 S forms. With differentiation of the postsynaptic membrane of the developing electrocytes, 13 S and 17 S forms replaced the slower-sedimenting forms. Concomitant with the formation of synaptic contacts, a transient increase in the 13 S form was followed by a dramatic accumulation of rapid-sedimenting 17 S form. The establishment of fully functional synapses was accompanied by an increase in the amount of the hydrophobic 6 S form. At birth, equal amounts of 6 S and 17 S form were found, with the other forms present in only trace amounts. The observed characteristic changes correlated with morphological and physiological events, indicating a close functional relationship between the accumulation of the 17 S form and synapse formation and the accumulation of the 6 S form and onset of function. 相似文献
4.
A wide-ranging examination of plastid (pt)DNA sequence homologies within
higher plant nuclear genomes (promiscuous DNA) was undertaken. Digestion
with methylation-sensitive restriction enzymes and Southern analysis was
used to distinguish plastid and nuclear DNA in order to assess the extent
of variability of promiscuous sequences within and between plant species.
Some species, such as Gossypium hirsutum (cotton), Nicotiana tabacum
(tobacco), and Chenopodium quinoa, showed homogenity of these sequences,
while intraspecific sequence variation was observed among different
cultivars of Pisum sativum (pea), Hordeum vulgare (barley), and Triticum
aestivum (wheat). Hypervariability of plastid sequence homologies was
identified in the nuclear genomes of Spinacea oleracea (spinach) and Beta
vulgaris (beet), in which individual plants were shown to possess a unique
spectrum of nuclear sequences with ptDNA homology. This hypervariability
apparently extended to somatic variation in B. vulgaris. No sequences with
ptDNA homology were identified by this method in the nuclear genome of
Arabidopsis thaliana.
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5.
6.
S J Andrews P T Brooks D C Hanbury C M King C M Prendergast G B Boustead T A McNicholas 《BMJ (Clinical research ed.)》2002,324(7335):454
ObjectivesTo compare ultrasonography and abdominal radiography with intravenous urography in the investigation of urinary tract infection in men.DesignProspective study in two hospital departments. Radiological procedures and urological assessments performed on different days by different cliniciansSettingDistrict general hospital.ParticipantsConsecutive series of men (n=114) referred to the department of urology for investigation of proved urinary tract infection.InterventionsUltrasonography and intravenous urography of renal tract and assessment of urinary flow rate. Clinical assessment, cystoscopy, urodynamic studies, and transrectal ultrasonography with biopsy.ResultsImportant abnormalities were seen in 53 of 100 fully evaluated patients, the most common being a poorly emptying bladder (34). The combination of plain radiographs of kidneys, ureter, and bladder and ultrasonography detected more abnormalities than intravenous urography alone. No important abnormality was missed by this combination (sensitivity 100% and specificity 93%).ConclusionsUltrasonography with abdominal radiography is as accurate as intravenous urography in detecting important urological abnormalities in men presenting with urinary tract infection. This combination is safer than intravenous urography and should be the initial investigation for such patients. Additional determination of urinary flow rate is useful for the assessment of an incompletely emptying bladder.
What is already known on this topic
Ultrasonography alone is the primary investigation of choice for urinary tract infection in children and womenUltrasonography has limited sensitivity for renal stones and poor sensitivity for ureteric stonesUrinary infection is less common in men than women and the risk factors are differentWhat this study adds
Ultrasonography is as effective as intravenous urography in men with urinary tract infection only when it is combined with plain radiographyIn men aged over 50 an incompletely emptying bladder is the most common abnormalityIn such patients determination of urinary flow rate is particularly helpful 相似文献7.
Characterization of Annexins in Mammalian Brain 总被引:3,自引:2,他引:1
Three annexins--p68, endonexin, and p32--have been isolated from porcine brain using their calcium-dependent affinity for membranes. Large amounts (20-50 mg/kg of tissue) of p68 and p32 can be isolated from cerebrum and cerebellum. The p68 is present as up to 0.3% of total porcine brain protein. The p68 and p32 from porcine brain bind to phosphatidic acid (half-maximal binding at 6 and 34 microM free calcium, respectively) and to phosphatidylserine (8 and 34 microM, respectively). They do not bind to phosphatidylcholine at calcium concentrations up to 1 mM. Two other major proteins (Mr 180,000 and Mr 76,000) were isolated with the annexins in a calcium-dependent manner but do not bind to phospholipids. The 180-kilodalton protein is the heavy chain of clathrin. From immunohistochemical studies, p68 is strongly associated with the plasma membranes of Purkinje cell bodies and dendrites in porcine cerebellum. It is also an intracellular component of Purkinje cells localized to perinuclear structures. Staining of axons in the white matter and granule cell layer was also seen. In contrast, p32 is completely absent from Purkinje cells and their dendrites; it is predominantly located in the molecular layer and in white matter of the cerebellar folds. The distribution of p32 may be consistent with a predominantly glial localization. 相似文献
8.
The leucocytes of three anguillid eels were studied using enzyme cytochemistry. Leucocytes were stained for peroxidase, alkaline phosphatase, acid phosphatase, aryl sulphatase, β-glucuronidase, N-acetyl-β-glucosaminidase, β-galactosidase, lysozyme, a variety of non-specific esterases, chloroacetate esterase and two proteases. All cells were negative for aryl sulphatase, β-glucuronidase, N-acetyl-β-glucosaminidase, and β-galactosidase. Very few neutrophils, thought to be mature, and all eosinophils contained peroxidase-positive granules, and some monocytes showed very weak peroxidase staining. All leucocytes lacked alkaline phosphatase, but all cells except lymphocytes and thrombocytes of A. dieffenbachii contained acid phosphatase. Neutrophil acid phosphatase released into phagosomes was associated with Escherischia coli bacteriolysis. Neutrophils also secrete lysozyme and, with monocytes, produce and secrete a variety of esterases. The possible interaction of lysozyme, acid phosphatase and esterases in bacteriolysis is discussed. 相似文献
9.
Two calcium-dependent proteins of apparent Mr 32,000 and 34,000 were isolated from bovine lung. Approx. 70 mg/kg of each was obtained. Two-dimensional gel electrophoresis in the presence of 8 M urea showed their apparent p/values to be 5.1 and 5.0, respectively. Both proteins are related immunologically to calelectrin from Torpedo marmorata. They also have very similar amino acid compositions to calelectrin. Partial sequence information shows that both proteins contain the highly conserved sequence described for the annexins, a new family of calcium-dependent membrane-binding proteins. In common with other members of this family, the new proteins bind to acidic phospholipids in a calcium-dependent manner. 相似文献
10.
JN Matthiessen 《Australian Journal of Entomology》1999,38(4):348-353
In field and laboratory studies, mortality of African black beetle, Heteronychus arator, in the winter-rainfall, Mediterranean-type climate region of south-western Australia was higher in the late immature stages during summer than in the early immature stages that occur during spring, a contrast to summer-rainfall climatic regions. Greatest mortality occurred around the pupal stage in contrasting soil types, despite drying differences in summer and supplementary watering in some plots. Sampling of natural populations confirmed experimental results that mortality in late immature stages is the major factor limiting H. arator populations under a Mediterranean-type climate. Inter-generation increase in H. arator abundance was uncommon, explaining the consistent abundance typically observed between years in south-western Australia. Random dispersal of newly emerged adults in autumn was inferred to restore uniformity in adult abundance between areas of varying favourability for immature survival. 相似文献