Nucleotide sequence of a rabbit IgG heavy chain from the recombinant F-I haplotype

We report the sequence of a cDNA encoding a rabbit immunoglobulin gamma heavy chain of d12 and e14 allotypes with high homology to partial cDNA sequences from rabbits of d11 and e15 allotypes. The encoded rabbit protein shows homologies with human (68-70%) and mouse (60-63%) gamma chains. The nucleotide sequence homologies of the CH domains range from 76-84% with human and 64-76% with mouse sequences. Comparison of the portion of VH encoding amino acid positions 34-112 with a previously determined VH sequence of the same allotype shows high conservation of sequences in the second and third framework segments but more marked differences both in length and encoded amino acids of the second and third complementarity-determining regions (CDRs). We also found a high degree of homology with a human genomic V-region, VH26 (77%) and a remarkable similarity between rabbit and human second CDR sequences and human genomic D minigenes. These results provide additional evidence that D minigene sequences share information with the CDR2 portion of VH regions.     

DIATOM MINERALIZATION OF SILICIC ACID. VI. THE EFFECTS OF MICROTUBULE INHIBITORS ON SILICIC ACID METABOLISM IN NAVICULA SAPROPHILA1

The role of microtubules in silicon metabolism leading to valve formation was investigated in the pennate diatom Navicula saprophila Lange-Bertalot & Bonik. By using synchronized cells blocked after mitosis and cytokinesis but prior to cell wall formation, effects due to inhibition of mitosis were eliminated. Cells were treated with three anti-microtubule drugs to assess the role of microtubules. Chemical analogs to two of the drugs provided controls for inhibition not related to microtubule disruption. Although all three anti-microtubule drugs reduced cell separation at high concentrations (1 × 10^?3 M), podophyllotoxin was the only drug which reduced cell separation at concentrations lower than 1 × 10^?5 M. None of the drugs at any concentration tested affected cell viability. There was no differential inhibitory effect between the active and inactive drugs on silicic acid transport, total uptake, incorporation, or pool formation. There was no qualitative difference between silica incorporated in treated and untreated cells. A colchicine binding component was isolated from N. saprophila. The characteristics of colchicine binding suggest this component may be tubulin. Microtubules do not appear to be involved in any of the steps of silicon metabolism leading to valve formation and yet they have profound influence on the symmetry and pattern of the mineralized product, the siliceous valve.     

Genetics and expression of kappa-type light chains in Basilea rabbits

In contrast to rabbits of b4, b5, b6, and b9 allotypes whose serum immunoglobulins (Igs) are predominantly composed of kappa-type light chains, rabbits of the mutant Basilea strain have serum Igs that are largely of lambda type. We prepared several antisera that recognized a minor K2 (bas) light chain that is produced by Basilea rabbits. With these antisera we identified the K2 (bas) isotype in the serum of the original b ⁹/b ⁹ male rabbit whose offspring displayed the Basilea mutant phenotype. It was present in one half of his nonmutant offspring which inherited b9 from him and another b allotype from their mothers. Breeding was conducted both in Basel and at the NIH to develop and maintain colonies of mutant Basilea strain rabbits. The data obtained during colony development confirm that the trait of expression of the bas allotype maps to the same genetic region (b locus) that is known to control the allelic b allotypes b4, b5, b6 and b9. Homozygotes or heterozygotes of b4, b5 or b6 allotype (b ^b /b ^b ) were mated with homozygous b ^bas /b ^bas rabbits to produce F₁s, and then F₂s as well as progeny of backcrosses to both homozygous parental types (b ^b /b ^b and b ^bas /b ^bas ) were produced. The bas allotype segregates as an allele (or pseudoallele) at the b locus although there was a deficiency in recovery of homozygous bas offspring in both the F₂ and backcross matings to b ^bas /b ^bas parental type in the NIH colony. This selective deficiency may reflect a deleterious effect on survival of homozygous bas progeny.The Basel Institute for Immunology was founded and is supported by F. Hoffmann La-Roche and Co., Ltd., Basel, Switzerland.     

Cobalt(III)-promoted hydrolysis of atp

The rate of phosphate hydrolysis of ATP in the substitution-inert complex Co(NH₃)₄ATP-has been examined in the presence and absence of [Co(cyclen)(H₂O)₂]³⁺. The rate of hydrolysis of Co(NH₃)₄ATP- in the absence of [Co(cyclen)(H₂O)₂]³⁺ is essentially independent of pH in the range 6.0 to 9.0, and the rate constant is 2.6 × 10^?5 sec ^?1 at pH 9.0, 40°C, and 1.0 M ionic strength Rate constants for the hydrolysis of Co(NH₃)₄ATP- in the presence of [Co(cyclen)(H₂O)₂]³⁺ are sharply dependent upon pH in the same range. The rate constants at pH 8.0, 8.6, and 9.0 are 8, 63, and 95 times larger than the rate constant at pH 7.0. At pH 9 the rate constant is 1.2 × 10^?3 sec^?1 for 16 mM Co(NH₃)₄ATP- in the presence of 10 mM [Co(cyclen)(H₂O)₂]³⁺. The proposed mechanism for hydrolysis involves the coordination of a phosphate group of Co(NH₃)₄ATP- by [Co(cyclen)(H₂O)₂]³⁺ to form a dinuclear species, followed by internal attack of coordinated hydroxide on the phosphate chain.     

Rapid step-gradient purification of mitochondrial DNA

A convenient modification of the step gradient (CsCl/ethidium bomide) procedure is described. This rapid method allows isolation of covalently closed circular DNA separated from contaminating proteins, RNA and chromosomal DNA in ca. 5 h. Large scale preparations can be performed for circular DNA from eukaryotic organelles (mitochondria). The protocol uses organelle pelleting/NaCl-sarcosyl incubation steps for mitochondria followed by a CsCl step gradient and exhibits yields equal to the conventional procedures. It results in DNA sufficiently pure to be used for restriction endonuclease analysis, subcloning, 5-end labeling, gel retention assays, and various types of hybridization.     

Properties of components of covariance of inbred relatives and their estimates in a maize population

Summary Properties of three parameterizations, denoted as the C-model, D-model and Q-model, for covariances of inbred relatives under assumptions of no linkage or epistasis are explored and compared. Additive variance in an inbred population with inbreeding coefficient F, ² _AF =(1+F) ² _A where ² _A is additive variance in a panmictic population, if Q-model parameters Q _xx and Q _xy are both zero. Conditions sufficient for this to hold are presented in terms of gene frequencies and dominance contrasts (homozygotes vs. heterozygotes). Some other properties and potential uses of estimates of components in the models are also discussed. Estimates of components in the D-model and Q-model were calculated from a maize (Zea mays L.) study from which estimates of components in the C-model were previously published. Of particular interest were the covariance (Q _xy ) of effects of alleles at complete homozygosity with inbreeding depression effects, the covariance (D ₁) of additive effects at panmixia with inbreeding depression effects and the within-locus variance (D ₂, alias Q _xx ) of inbreeding depression effects. Estimates of Q _xy , D ₁, and D ₂ were small and nonsignificant in most cases. For ear height in the second year of the study, D ₂ appeared to be a major component. In some cases, results were obtained which had contradictory implications (negative D ₂ coupled with positive Q _xy or D ₁, and positive D ₂ coupled with negative ² _D ). A negative estimate of one or the other of ² _D or ² _A was obtained in one of the two within-year analyses for every character. Problems in getting realistic results were thought to be owing to excessive multicollinearity among the coefficients of the components in the expectations of the covariances of the kinds of relatives included in the study. Implications for future studies of this kind are discussed.Journal Article No. 87-3-14 of the Kentucky Agricultural Experiment Station published with the approval of the Director     

Elevation in plasma glucagon levels in response to stress in squirrel monkeys: comparisons of two subspecies (Saimiri sciureus boliviensis and Saimiri sciureus sciureus)

Bolivian (Bo) and Brazilian (Br) squirrel monkeys (SMs) were captured and restrained to determine patterns of glucagon and glucose response. In both subspecies, plasma glucagon and glucose levels rose rapidly in response to restraint procedures; glucagon levels in BrSMs and glucose levels in both subspecies returned to basal values in 15 minutes. The magnitude of the glucagon and glucose responses differed significantly between BoSMs and BrSMs.     

Vegetation patterns,microtopography, and soils on a Chihuahuan desert playa

Abstract. Spatial patterns of vegetation on an ephemeral lake bed (playa) in the northern Chihuahuan desert were closely correlated with elevation. Distributions of species along a 265 m transect from the center to the edge of the playa showed abrupt boundaries at 110 m and 220 m. These boundaries seem related to the maximum elevation covered with standing water following complete flooding, and to an edaphic boundary between heavy clay soils at the center of the playa and adjacent soils. The complete turnover in species composition across this transect, with an elevation change of only 85 cm, indicates that environmental gradients resulting from flooding and soil development are steep. Vegetative patterns within the lowest part of the playa were patchy, with patch diameters ranging from 2 to 5 m. These patches appear to be produced by differences in the duration and frequency of flooding between small knolls and depressions resulting from gilgai microtopography.