The rabbit alpha-like globin gene cluster is polymorphic both in the sizes of BamHI fragments and in the numbers of duplicated sets of genes

The alpha-like globin gene cluster in rabbits contains embryonic zeta- globin genes, an adult alpha-globin gene, and theta-globin genes of undetermined function. The basic arrangement of genes, deduced from analysis of cloned DNA fragments, is 5'-zeta 0-zeta 1-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3'. However, the pattern of restriction fragments containing zeta- and theta-globin genes varies among individual rabbits. Analysis of BamHI fragments of genomic DNA from 24 New Zealand white rabbits revealed eight different patterns of fragments containing zeta-globin genes. The large BamHI fragments containing genes zeta 0 and zeta 1 are polymorphic in length, whereas a 1.9-kb fragment containing the zeta 2 gene and the 3.5-kb fragment containing the zeta 3 gene do not vary in size. In contrast to this constancy in the size of the restriction fragments, the copy number of the zeta 2 and zeta 3 genes does vary among different rabbits. No length polymorphism was detected in the BamHI fragments containing the theta-globin genes, but again the copy number varies for restriction fragments containing the theta 2 gene. The alpha 1- and theta 1-globin genes are located in a nonpolymorphic 7.2-kb BamHI fragment. The combined data from hybridization with both zeta and theta probes shows that the BamHI cleavage pattern does not vary within the region 5'-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3', but the pattern genomic blot-hybridization patterns for the progeny of parental rabbits with different zeta-globin gene patterns shows that the polymorphic patterns are inherited in a Mendelian fashion. Two different haplotypes have been mapped based on the genomic blot-hybridization data. The variation in the alpha-like globin gene cluster in the rabbit population results both from differences in the copy number of the duplication block containing the zeta-zeta-theta gene set and from the presence or absence of polymorphic BamHI sites.      

Trimethyloxonium modification of single batrachotoxin-activated sodium channels in planar bilayers. Changes in unit conductance and in block by saxitoxin and calcium

Single batrachotoxin-activated sodium channels from rat brain were modified by trimethyloxonium (TMO) after incorporation in planar lipid bilayers. TMO modification eliminated saxitoxin (STX) sensitivity, reduced the single channel conductance by 37%, and reduced calcium block of inward sodium currents. These effects always occurred concomitantly, in an all-or-none fashion. Calcium and STX protected sodium channels from TMO modification with potencies similar to their affinities for block. Calcium inhibited STX binding to rat brain membrane vesicles and relieved toxin block of channels in bilayers, apparently by competing with STX for the toxin binding site. These results suggest that toxins, permeant cations, and blocking cations can interact with a common site on the sodium channel near the extracellular surface. It is likely that permeant cations transiently bind to this superficial site, as the first of several steps in passing inward through the channel.     

Standardization of factor VIII: establishment and use of secondary standards

Two secondary standards for use in routine assays of Factor VIII in therapeutic concentrates and in patients, plasmas, respectively, have been established in a multicenter collaborative study. In order to assess the effect of the adoption of these preparations as common Secondary Standards a comparative assay has been performed: one sample of a Factor VIII concentrate of intermediate purity and one plasma sample have been tested in two laboratories for Factor VIII:C activity using as reference, among others, the common working standard. Analysis of the results shows that with the plasma sample the differences of the estimates obtained with any of the references in our two laboratories were not statistically significant (P greater than 0.3), while with the concentrate sample the differences were always statistically significant (P less than 0.005). The study shows that the adoption of common working standards (besides the uniformity in assay method, reagents and basic equipment) is not sufficient to eliminate interlaboratory variation in the measurement of Factor VIII:C.     

The structure and behavior of the nucleolus organizers in mammalian cells

The regularly occurring secondary constrictions on metaphase chromosomes of mammalian cells prove to be nucleolus organizers as expected. The expression of nucleolus organizers as secondary constrictions, however, varies from cell to cell and from tissue to tissue, including cultivation in vitro. Electron micrographs of the organizer region show that the nucleolus organizer at metaphase is not a constriction. The width of the organizer area is the same as the condensed chromosomal arms; but the filaments, which are the major components of this region, show a diameter of 50–70 Å. The condensed chromosome arms consist of filaments 150–200 Å in diameter. In some mammalian species, structures similar to the nucleolus organizer are located at the end of chromosomes. These may be terminal nucleolus organizers.Supported in part by Research Grants DRG-269 from Damon Runyon Memorial Fund for Cancer Research, E-286 from American Cancer Society, and HD-2590 from National Institutes of Health.     

Detection of coliphages and enteroviruses in sewage and aerosol from an activated sludge wastewater treatment plant

Coliphages and enteroviruses were monitored over 12 months in sewage and air adjacent to an activated sludge plant. Both showed temporal variation but the mean count of phages in enterovirus-positive samples was not significantly different from that in enterovirus-negative samples. Hence coliphages are not necessarily a good indicator of enteroviruses in sewage and aerosols.     

Analysis of the frequency and distribution of sister chromatid exchanges in cultured human lymphocytes

Summary Lymphocytes from 20 normal subjects (11 male and 9 female) were examined for the frequency and location of sister chromatid exchanges (SCE) by the BrdU—Giemsa method. The mean frequency of SCE was 6.37 with little significant variation. One subject had a high number of exchanges in chromosome 1 while the remainder showed a random distribution of exchanges between chromosomes. The frequency of exchanges generally increased with chromosome length. However, chromosome 1, 2 and the B group had more exchanges than expected while the E, F and G groups had less than expected. The distribution of exchanges in chromosomes 1, 2 and the B group was non-random with a concentration of exchanges below the centromere and to a lesser extent on the distal portion of the long arm. The majority of exchanges appeared to occur at the junction between the dark and light G bands. It is suggested that the concentration of exchanges may reflect differences in BrdU incorporation along the length of the chromosome.     

Combination of silver and fluorescent staining for metaphase chromosomes.

A convenient and reliable method for simulatneous visualization of silver staining (Ag-NOR) of the nucleolus organizers and fluorescent bandings in metaphase chromosomes is described. Studies employing this combined procedure on human chromosomes revealed that the Ag-NOR patterns may be characteristic for each chromosome of each individual.     

Localization of Drosophila nasutoides satellite DNAs in metaphase chromosomes

Metaphase chromosomes of D. nasutoides were hybridized situ with ³H-cRNA synthesized from the four satellites which make up 50–60% of the total DNA of this species. All four satellites were localized in the large, metacentric, heterochromatic chromosome four. They did not, however, appear to hybridize to centromeric or other constitutive heterochromatin, nor did they, with the exception of satellite I, seem to hybridize in the specific regions of chromosome four which, on the basis of C, Q, and H banding and AT contents, were predicted to contain some of these satellites. —Comparison of grain patterns with the results of fluorescent staining indicated that satellite-bearing heterochromatin was not always associated with other fractions of constitutive heterochromatin in interphase nuclei and was, at least partially, decondensed in some larger nuclei.     

Association between pygmy right whales (Caperea marginata) and areas of high marine productivity off Australia and New Zealand

Abstract

Opportunistic sightings and strandings of Caperea marginata (n=196) from the vicinity of Australia and New Zealand (1884 to early 2007) were used to relate geographic and temporal patterns to oceanographic and broad-scale climatic variability. Records were not uniformly distributed along the coast and more (69%) were from Australia than New Zealand. Seven coastal whale ‘hotspots’ were identified which accounted for 61% of records with locality data. Half of the hotspot records were from southeast (37) and northwest (20) Tasmania—others each had 9–15 events. Upwelling and/or high zooplankton abundance has been documented near all whale hotspots. Records of C. marginata occurred in all months, with 75% in spring and summer. Inter-annual variability showed broad agreement between increased whale records (usually in spring/summer) and strongly positive ‘Niño 3.4’ during 1980–1995 but not thereafter. Coastal upwelling and productivity increase during climatic phenomena such as El Niño and are likely to be quickly beneficial to plankton-feeding whales such as C. marginata.