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B N White

Publications and source records attributed to B N White.

16 recordsLinked to original sources
PubMed1992

Application of DNA fingerprinting to the recovery program of the endangered Puerto Rican parrot.

The Puerto Rican parrot was reduced to approximately 13 animals in 1975 and as a conservation measure, a captive population was established from a few founders taken from the wild between 1973 and 1983. The number of successful breeding pairs in captivity has been low, and the captive breeding program has not been as productive as that of the closely related Hispaniolan parrot. Therefore, a genetic study was initiated to examine the relative levels of relatedness of the captive founders using levels of bandsharing in DNA fingerprints. Unrelated captive founder Puerto Rican parrots had the same average level of bandsharing (0.41) as second-degree relatives of the Hispaniolan parrot (0.38, P > 0.05), with an inbreeding coefficient of 0.04. High levels of bandsharing (> 40%) between pairs of males and females correlated with reproductive failure, suggesting that inbreeding depression is partly responsible for the low number of breeding pairs. Consequently, DNA profiling can be used to guide the captive breeding program for the Puerto Rican parrot, and other endangered species, by identifying pairs of males and females with low levels of bandsharing.

Animals↗
PubMed1992

Characterization and assessment of an avian repetitive DNA sequence as an icterid phylogenetic marker.

The first tandemly repeated sequence examined in a passerine bird, a 431-bp PstI fragment named pMAT1, has been cloned from the genome of the brown-headed cowbird (Molothrus ater). The sequence represents about 5-10% of the genome (about 4 x 10(5) copies) and yields prominent ethidium bromide stained bands when genomic DNA cut with a variety of restriction enzymes is electrophoresed in agarose gels. A particularly striking ladder of fragments is apparent when the DNA is cut with HinfI, indicative of a tandem arrangement of the monomer. The cloned PstI monomer has been sequenced, revealing no internal repeated structure. There are sequences that hybridize with pMAT1 found in related nine-primaried oscines but not in more distantly related oscines, suboscines, or nonpasserine species. Little sequence similarity to tandemly repeated PstI cut sequences from the merlin (Falco columbarius), saurus crane (Grus antigone), or Puerto Rican parrot (Amazona vittata) or to HinfI digested sequence from the Toulouse goose (Anser anser) was detected. The isolated sequence was used as a probe to examine DNA samples of eight members of the tribe Icterini. This examination revealed phylogenetically informative characters. The repeat contains cutting sites from a number of restriction enzymes, which, if sufficiently polymorphic, would provide new phylogenetic characters. Sequences like these, conserved within a species, but variable between closely related species, may be very useful for phylogenetic studies of closely related taxa.

Animals↗
PubMed1990

Genetic mapping of two new DNA markers in Xq26-q28 relative to the fragile-X syndrome locus.

We have characterized and genetically mapped two new DNA markers (DXS311 and DXS312) with respect to 10 existing loci in Xq26----Xq28 in a set of 15 families in which the fragile-X [fra(X)] syndrome was segregating. Two-point and multipoint linkage analyses were performed taking into account the incomplete penetrance of the fra(X) mutation. The most likely order on the basis of these data is centromere-DXS79-DXS10-DXS311-DXS86-(F9-DXS99 )-(DXS98-DXS312)-fra(X)-DXS52- DXS15-F8C-telomere. DXS98 and one of the new loci, DXS312, were found to be the proximal markers closest to the fra(X) locus. The order F9-(DXS98-DXS312)-fra(X) was found to be 5.9 x 10(4) times more likely than the order (DXS98-DXS312)-F9-fra(X).

Chromosome Mapping↗
PubMed1979

The purification of Q-containing tRNAs by periodate modification. Purification and nucleoside composition of two related Drosophila tyrosine tRNAs.

A simple procedure for the purification of Drosophila tRNAs which contain the hypermodified nucleoside Q was developed. The cis-diol group of Q renders it susceptible to attack by sodium periodate, with the resultant formation of a hydrophobic pyrrol ring structure. The increase in hydrophobicity after periodate modification, of those tRNA species which contain the Q nucleoside, causes them to be selectively retarded on benzoylated DEAE-cellulose or RPC-5 columns, and allows their isolation in essentially pure form. Utilizing this property, the Q-containing tyrosine tRNA from Drosophila, tRNATyr1delta, was purified. The non-Q-containing tyrosine tRNA, tRNA, tRNATyr1gamma, was also purified, and the nucleoside compositions of the two were determined and compared. In addition to the Q nucleoside, these tRNAs appear to differ by the presence (tRNATyr1delta) or absence (tRNATyr1gamma) of 5-methylcytidine. In all other respects, these tRNAs appear to be identical, and are probably products of the same gene which differ in their levels of post-transcriptional modification.

Animals↗
PubMed1979

The effect of aggregation and release on platelet prothrombin-converting activity.

Platelets provide a procoagulant activity for the conversion of prothrombin to thrombin during normal hemostatis. This activity designated as platelet prothrombin-converting activity (PPCA) was monitored as rate of thrombin production in a two-stage assay using gel-filtered bovine platelets, factor Xa, and prothrombin. Expression of PPCA was not associated with ADP-induced release or platelet shape change but was associated with aggregation. Release of the contents of dense bodies, measured by release of 14C-5-hydroxytryptamine, was not required for expression of PPCA during platelet aggregation. During the PPCA assay, 5-hydroxytrypamine was released, but only after onset of thrombin production. Furthermore, the release of 5-hydroxytryptamine was retarded during the assay by the addition of 2 mM theophylline and 100 nM prostaglandin E1 without a comparable reduction in PPCA. In addition, 125I-factor-Xa was bound in greater amounts to platelets (aspirin-treated) after ADP-induced aggregation (without detectable release) than to unactivated control platelets. Finally, the PPCA of the ADP-activated platelets was saturated with respect to factors Xa and Va at less than 1 nM concentrations, indicating that the aggregation induced by ADP leads to the exposure of specific procoagulant sites by some process other than dense body secretion.

Animals↗
PubMed1978

The role of the guanine insertion enzyme in O-biosynthesis in Drosophila melanogaster.

Drosophila tRNA can be guanylated by a crude enzyme from rabbit reticulocytes. Guanylating activity is also present in crude extracts of adult Drosophila. A major product of this reaction as well as several minor ones were resolved by RPC-5 chromatography. The main substrate of both the Drosophila and rabbit reticulocyte enzymes was the non-Q-containing aspartic acid tRNA, tRNA2gammaAsp. The QU-lacking (gamma) forms of asparagine, histidine and tyrosine tRNAs were also substrates and gave rise to the minor products of the reaction. In contrast, the Q- or Q*-containing (delta) forms of these tRNAs appear not to be substrates. The evidence strongly suggests that the guanyating enzyme is involved in Q biosynthesis and would be better termed a guanine replacement or pre-Q insertion enzyme.

Animals↗
PubMed1977

A doubtful relationship between tyrosine tRNA and suppression of the vermilion mutant in Drosophila.

The conditions under which Drosophila melanogaster are grown markedly influence the amount of the hypermodified nucleoside Q found in certain tRNAs. This effect on Q biosynthesis was found in both the wild-type and the suppressor of sable [su(s)2] mutant. Suppressed vermilion flies [su(s)2v; bw] with 78% of the tyrosine tRNA in the Q-lacking (gamma) form had brown eyes indistinguishible from su(s)2v; bw flies with only 6% of the tyrosine tRNA in the gamma form. The proposal that this tRNA is a specific inhibitor or tryptophan pyrrolase in vermilion flies, and that its absence in su(s)2 flies is the mechanism of suppression is not consistent with these results. In addition, the su(s)2 locus does not seem to be primarily responsible for controlling Q biosynthesis as previously suggested.

Animals↗
PubMed1977

Metabolic relationships between green hydra and its symbiotic algae.

1. Hydra that maintain algal symbionts evidenced three modes of metabolism depending upon the nutritional state of the host and the photoperiodic conditions under which the animals were maintained. Animals either fed or fasted but maintained in the dark exhibited an RQ of 0.725 indicating fat metabolism. When they were fed Artemia nauplii and maintained in the light green hydra exhibited a mixed metabolism of carbohydrate and fat which gave an RQ of 0.862. Fasting green hydra, when maintained in the light, showed a pronounced carbohydrate metabolism typified by an RQ of 0.970. 2. Aposymbiotic hydra, whether fed or fasted, exhibited an RQ of 0.725 indicating a high degree of fat metabolism. 3. Symbiotic hydra which were fed and maintained in the light demonstrated a respiration rate of 14.4 microliter/day per hydra, which was 2.5 times greater than animals (symbiotic or aposymbiotic) maintained under any other condition of fasting or photoperiod. It is hypothesized that the enhanced respiration observed in these animals is due to the metabolic activities of the symbiotic algae associated with reproduction and development. 4. Calculations based on respiratory measurements and indirect calorimetry suggest that hydra consume approximately 0.0320 calories per day and that symbiotic algae may supply up to 69% of the host caloric requirements via the translocation of approximately 5 microgram of carbohydrate when the host is fasting and light is provided.

Animals↗
PubMed1975

Studies on lysine, glutamine and glutamic acid tRNAs from Drosophila.

The minor bases present in the family of Drosophila tRNAs recognising codons of the type NAA or NAG have been studied. Under standard aminoacylating conditions, the acceptor activities of BrCN-treated tRNA-Lys-5 tRNA-Glu-4 and tRNA-G1n-4 were completely eliminated, suggesting the presence of 2-thiouridine derivatives. The two major lysine tRNA species (tRNA-Lys-2 and tRNA-Lys-5) were purified and their nucleoside content determined both directly and by the tritium derivative technique. Both tRNAs contain 1-methyladenosine, N-2-dimethylguanosine, 7-methylguanosine, 5-methylcytidine, pseudouridine and dihydrouridine, and tRNA-Lys-5 contains 1-methylguanosine. Neither species contain ribothymidine, although both may contain 2'-O-methyl ribothymidine. A nucleoside with ultraviolet spectral properties similar to N-4-acetylcytidine was found in tRNA-Lys-5 and a nucleoside with chromatographic properties the same as N-[9-beta-D-ribofuranosyl)-purin-6-yl-carbamoyl] threonine was found in tRNA-Lys-2. A 2-thiouridine derivative was not found in tRNA-Lys-5 using these chromatographic techniques.

Alanine↗
PubMed1975

An analysis of five serine transfer ribonucleic acids from Drosophila.

Crude tRNA from adult Drosophila melanogaster was fractionated on bensoylated-diethylaminoethyl cellulose columns. The eluate was assayed for both amino acid acceptance and cytokinin activity. Most of the cytokinin activity was associated with a peak of serine acceptance. The five major serine tRNAs were purified by chromatography on benzoylated-dietyhlaminoethyl cellulose and reversed phase chromatography-5 columns. The major species, tRNA7-Ser was isolated from this tRNA and was shown to be N-6-(delta-2-isopentenyl)adenosine (i-6A) on the basis of ultraviolet and mass spectral data. The nucleoside somposition of all five serine tRNAs was determined directly and by the 3-H derivative method. They all contain pseudouridine, ribothymidine, 1-methyladenosine, 5-methylcytosine, N-2-dimethylguanosine, 5, 6-hydrouridine, and 3-methylcytosine, while two contain an unidentified nucleoside, and one containes 1-methylguanosine. These techniques also confirmed the presence of i-6A in tRNA7-Ser as well as showing its presence in tRNA6-Ser and tRNA4-Ser. These three tRNA-Ser species exhibit marked changes in elution from reversed phase chromatography-5 columns as a function of temperature and this may be related to their minor base composition. The tRNAs-Ser were bound to ribosomes in response to the following triplets: tRNA2-Ser, AGU, AGC; tRNA4-Ser, UCG; tRNA5-Ser, AGU, AGC; tRNA7-Ser, UCG.

Adenosine↗
PubMedDate not supplied

Sizing bands on autoradiograms: a study of precision for scoring DNA fingerprints.

We replicated DNA fingerprints of snapping turtles (Chelydra serpentina) and hypervariable restriction fragments of red-winged blackbirds (Agelaius phoeniceus) to estimate the between-blot and between-lane components of variance in molecular weights of restriction fragments. Molecular weight standards were included in every lane, and bands were sized using a sonic digitizer. In both studies, a strong positive correlation was found between band size and coefficient of variation (CV; mean = 0.7%). In the DNA fingerprint study, 26% of the variance in estimates of band size was due to differences between blots, 10% due to differences between lanes on the same blot, and 64% due to error in the digitizing process. In the restriction fragment length polymorphism (RFLP) study, 16% of the variance was due to difference between lanes, and 84% to digitizing. Statistical models were developed to measure the effect of sizing error on identifying identical fragments in different lanes or on different blots, in categorizing distinct alleles, and in determining the size of bins in operational allele definitions. We suggest that the distance between bands be at least 2.8 standard deviations (SD) before they are declared different at alpha = 0.05, and 3.7 SD for alpha = 0.01. A variation in CVs strongly indicates that empirical relationships between SD and band size must be used to decide if two bands represent the same allele. Alleles must be at least 3.9 SD apart before the chance of assigning new observations in error falls below 0.05. We suggest that a minimum bin width of 16 SD is necessary before the chances of assigning a band to the wrong bin falls below 0.05.

Alleles↗