An Empirical Exploration of the (δμ)2 Genetic Distance for 213 Human Microsatellite Markers

Microsatellites are now used ubiquitously as genetic markers. One important application is to the assessment of population subdivision and phylogenetic relatedness. Such applications require a method of estimation of genetic distance. Here we examine the most widely used measure of microsatellite genetic distance, Goldstein et al.'s delta-mu squared ([delta mu]2), with respect to a large data set of 213 markers typed across samples from four diverse human populations. We find that (delta mu)2 yields plausible interpopulation distances. For the first time, we report significant interpopulation differences in mean microsatellite length, although the effect of these differences on (delta mu)2 is negligible. However, we also show that the method is extremely sensitive to one or two loci that contribute extreme values, even when a sample size of >200 loci is used. Some of these extreme loci can be removed on the grounds that some alleles carry large indels, but for others there is no clear justification for exclusion a priori. Our data suggest a rather recent African/non-African split, with an upper limit of some 70,000-80,000 years ago.     

Resonance Raman spectroscopy shows different temperature-dependent coordination equilibria for native horseradish and cytochrome c peroxidase

Resonance Raman spectra are reported for native horseradish peroxidase (HRP) and cytochrome c peroxidase (CCP) at 290, 77 and 9 K, using 406.7 nm excitation, in resonance with the Soret electronic transition. The spectra reveal temperature-dependent equilibria involving changes in coordination or spin state. At 290 K and pH 6.5, CCP contains a mixture of 5- and 6-coordinate high-spin Fe^III heme while at 9 K the equilibrium is shifted entirely to the 6-coordinate species. The spectra indicate weak binding of H₂O to the heme Pe, consistent with the long distance, 2.4 Å, seen in the crystal structure. At 290 K HRP also contains a mixture of high-spin Fe^III hemes with the 5-coordinate form predominant. At low temperature, a small 6-coordinate high-spin component remains but the 5-coordinate high-spin spectrum is replaced by another which is characteristic either of 6-coordinate low-spin or 5-coordinate intermediate spin heme. The latter species is definitely indicated by previous EPR studies at low temperature. This behavior implies that, in contrast to CCP, the distal coordination site of HRP is only partially occupied by H₂O at any temperature and that lowering the temperature significantly weakens the Fe-proximal imidazole bond. Consistent with this inference, the 77 K spectrum of reduced HRP shows an appreciable fraction of molecules having an Fe-imidazole stretching frequency of 222 cm⁻¹, a value indicating weakened H-bonding of the proximal imidazole.Resonance Roman spectroscopyHorseradish peroxidaseCytochrome c peroxidaseCoordination equilibrium     

An investigation of number-concept appreciation in a rhesus monkey

In order to determine if nonhuman primates have some type of number-concept appreciation, the ability to form a concept of the third object in a row of three, four, five, six or seven objects was studied in an adolescent rhesus monkey. The problem was presented to the subject in a Wisconsin General Test Apparatus. Square wooden blocks, placed on a 45-hole formboard were used as the experimental stimuli. Position of rows of blocks was varied, either being placed in the center of the first row or randomly on the formboard. The subject learned to discriminate the third block in a row of blocks in a total of 62 days. The results of the present experiment indicate that monkeys can learn the concept of third. These results agree with those of other studies of number concept in nonhuman primates and lend further support to the idea that nonhuman primates have at least some type of number appreciation.     

Implications of testicular constrictions on spermatogenesis in Lake Ontario lake trout, Salvelinus namaycush

This study examines the histological significance of a testicular anomaly among hatcheryraised lake trout, Salvelinus namaycush , introduced into Lake Ontario as yearlings and subsequently recaptured at ages ranging from 4 to 7 years. The anomaly has been termed a constriction. Histological examination revealed that lake trout with constricted testes demonstrated delayed cycles of spermatogenesis throughout the testes at spawning time compared with normal testes. Constrictions were formed when spermatogonia within an adjacent group of lobules failed to undergo mitosis, hypertrophied and were subsequently resorbed. The walls of these lobules subsequently collapsed and were resorbed and replaced by dense fibrous connective tissue. The significance of these observations in relation to hormonal mechanisms and its potential effect upon reproduction in these fish is discussed.     

Thrombocyte counting with the Laborscale (PSL-1/PSA-1) particle-counting instrument by Medicor (Budapest/Hungary) and thrombocyte volume analysis in the diagnosis of selected thrombocytopathies

A thrombocyte counting technique is presented in comparison with the chambre counting according to the German Book of Medicaments (DAB 7 D.L.) GDR on the particle counting device "Laborscale" (PSL-1/PSA-1) of Medicor by using a thrombofuge (70 g). The composition of reagents accounts for problems of measurement which are caused by the device and influences the separation of particles. The possibility of recording the curve of thrombocyte volume distribution and calculating the average thrombocyte volume (VM) is demonstrated by means of a normal collective of test persons as well as by intravascular disorders of haemostasis and during cytostatic therapy.     

HER-2/neu oncogene expression, DNA ploidy and proliferation index in breast cancer.

HER-2/neu gene expression, DNA ploidy and proliferation index were studied in 250 cases of breast cancer. Expression of HER-2/neu was determined by using an antibody to the HER-2/neu receptor. Ki-67 antibody was used to determine the proliferation index of the breast cancers, and the Feulgen method was used to assess DNA amounts in the tumor cells. Histochemical staining was quantitated by image analysis. Of the cancers studied, 72 were positive for overexpression of HER-2/neu protein; of these, 62 (86%) possessed near-tetraploid DNA content, and 47 (65%) had more than one G0G1 stem line (polyploid) of DNA distribution. Cells from the cases negative for HER/2-neu overexpression contained DNA amounts that ranged from diploid to varying degrees of aneuploid. A significant difference in the amounts of cellular proliferation in HER-2/neu overexpressing cancers was found between those that expressed the HER-2/neu receptor on their membranes and those that exhibited mainly cytoplasmic receptors.     

Analysis of Streptomyces avermitilis genes required for avermectin biosynthesis utilizing a novel integration vector.

An integration vector for gene analysis in Streptomyces has been constructed. This vector replicates in Escherichia coli, and integrates into Streptomyces by homologous recombination between a cloned fragment and the genome. To overcome methylation-specific restriction barriers, an E. coli mutant triply defective in DNA methylation was constructed as a source for the integration plasmids. The frequency of integration of pVE616 derivatives into the Streptomyces avermitilis genome was proportional to the size of the cloned DNA. Derivatives of pVE616, containing fragments from pVE650, a plasmid with a 24-kb insert of S. avermitilis DNA, were used in complementation analyses of seven S. avermitilis mutants defective in glycosylation of avermectin (Av). Three complementation groups, located in a 7-kb region, were identified. Derivatives of pVE616, containing fragments from the 18-kb of DNA adjacent to the glycosylation region, were integrated into an Av producer. Av produced from the integrants was substantially reduced, indicating that the 18 kb also encodes gene products which are involved in Av biosynthesis.     

Simulation of Tumor-Specific Delivery of Radioligand Comparison of One Step,Two Step,and Genetic Transduction Systems

A mathematical model simulation was performed to estimate the amount of radioactivity in plasma, normal tissues, and tumor tissue through three delivery approaches: one step radiolabeled monoclonal antibody (MAb) CC49 i.v. bolus injection, two step method with biotin conjugated CC49 i.v. bolus injection followed 72 hours later by i.v. bolus radiolabeled streptavidin injection, and gene therapy method to express biotin on the tumor cell surface followed by i.v. bolus radiolabeled streptavidin injection. The mathematical model was built based on a system of ordinary differential equations consisting of inputs and outputs of model components in plasma, normal tissues, and tumor tissue. Through computer modeling, we calculated concentrations of each component for plasma, tumor and normal tissues at various time points. Radioactivity ratios of tumor to plasma and tumor to normal tissues increased with time. The increase of tumor to normal tissue ratios was much faster for the gene therapy approach than for single step and two step approaches, e.g., a ratio of 24.26 vs. 2.06 and 6.24 at 72 hours after radioligand injection. Radioactivity ratios predicted by the model varied with the amount of radioactivity injected and the time interval between injections. The model could be used to evaluate different radioimmunotherapy strategies and to predict radioactivity biodistribution using other receptor-ligand systems.     

Symbiotic Role of the Viable but Nonculturable State of Vibrio fischeri in Hawaiian Coastal Seawater

To achieve functional bioluminescence, the developing light organ of newly hatched juveniles of the Hawaiian squid Euprymna scolopes must become colonized by luminous, symbiosis-competent Vibrio fischeri present in the ambient seawater. This benign infection occurs rapidly in animals placed in seawater from the host's natural habitat. Therefore, it was surprising that colony hybridization studies with a V. fischeri-specific luxA gene probe indicated the presence of only about 2 CFU of V. fischeri per ml of this infective seawater. To examine this paradox, we estimated the total concentration of V. fischeri cells present in seawater from the host's habitat in two additional ways. In the first approach, the total bacterial assemblage in samples of seawater was collected on polycarbonate membrane filters and used as a source of both a crude cell lysate and purified DNA. These preparations were then assayed by quantitative DNA-DNA hybridization with the luxA gene probe. The results suggested the presence of between 200 and 400 cells of V. fischeri per ml of natural seawater, a concentration more than 100 times that revealed by colony hybridization. In the second approach, we amplified V. fischeri-specific luxA sequences from microliter volumes of natural seawater by PCR. Most-probable-number analyses of the frequency of positive PCR results from cell lysates in these small volumes gave an estimate of the concentration of V. fischeri luxA gene targets of between 130 and 1,680 copies per ml. From these measurements, we conclude that in their natural seawater environment, the majority of V. fischeri cells become nonculturable while remaining viable and symbiotically infective. Experimental studies indicated that V. fischeri cells suspended in natural Hawaiian seawater enter such a state within a few days.     

The effects of prostaglandin F2α on the fine structure of the corpus luteum of the pregnant hamster

Summary The commonest intracellular organelle characteristic of the Phylum Cnidaria or Coelenterata (Subclass Zoantharia) is the spirocyst. Based on scanning and transmission electron microscopy of the tentacles of sea anemones and corals, it appears that the tip of the spirocyst is either exposed to the environment or covered by a thin plasma membrane and often has a pebbled or knobby appearance. Surrounding the spirocyst tip is a ring-like structure which seems to be formed by the junction of the enclosing cell (the spirocyte) and the tip of the spirocyst. The spirocyst thread is continuous with the capsule wall and emerges from within the apical ring during discharge. No ciliary structures appear to be associated with spirocysts. Instead, two different types of microvilli have been found: short microvilli on the spirocyte itself and long microvilli furnished by the cell or cells surrounding the spirocyte. The significance of these findings is discussed in relation to the reception of stimuli for spirocyst discharge.Thanks are due Dr. Cadet Hand for the use of facilities of the Bodega Marine Laboratory of the University of California and Dr. R.K. Thompson, P. Nemanic, H. Sampson, F. Doroshow, E. Chang and B. Miller for expert technical assistance. The use of the facilities of the Electron Microscope Laboratory and the Electronics Research Laboratory of the University of California and the Electron Microscope Laboratory of the Florida State University is gratefully acknowledged. Part of this work was made possible by NSF Grant # GB-40547 to the senior author.