Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis)

For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.     

A new statistical test for linkage heterogeneity.

A new, statistical test for linkage heterogeneity is described. It is a likelihood-ratio test based on a beta distribution for the prior distribution of the recombination fraction among families (or individuals). The null distribution for this statistic (called the B-test) is derived under a broad range of circumstances. Two other heterogeneity test statistics--the admixture test or A-test first described by Smith and Morton's test (here referred to as the K-test)--are also examined. The probability distribution for the K-test statistic is very sensitive to family size, whereas the other two statistics are not. All three statistics are somewhat sensitive to the magnitude of the recombination fraction theta. Critical values for each of the test statistics are given. A conservative approximation for both the A-test and B-test is given by a chi 2 distribution when P/2 instead of P is used for the observed significance level. In terms of power, the B-test performs best among the three tests over a broad range of alternate heterogeneity hypotheses--except for the specific case of admixture with loose linkage, in which the A-test performs best. Overall, the difference in power among the three tests is not large. An application to some recently published data on the fragile-X syndrome and X-chromosome markers is given.     

The relationship between maternal age and chromosome size in autosomal trisomy.

The pattern of maternal age-specific incidence of autosomal trisomy in spontaneous abortions was examined for each chromosome for which a sufficient number of trisomies was observed. This included chromosomes 2, 4, 7-10, 13-16, 18, and 20-22. The rate of increase after age 30 for each of the small chromosomes (groups D-G) was similar, with the exception of chromosome 16, which showed a significantly shallower rate. The C group chromosomes tended to have an intermediate rate of increase after age 30, with the exception of chromosome 7, which had a pattern similar to the smaller chromosomes. The larger chromosomes (2 and 4) had the smallest rate of increase. There was a significant relationship between chromosome size and rate of increase after age 30 (after excluding chromosome 16), but not with rate of increase before age 30. The results suggest that autosomal trisomies may be of heterogeneous origin, with a maternal age-related factor associated with chromosome size and other sources unrelated to chromosome size. Additional evidence for and against this hypothesis is discussed.     

Activating and 'anxiogenic' effects of corticotropin releasing factor are not inhibited by blockade of the pituitary-adrenal system with dexamethasone

Central administration of corticotropin releasing factor (CRF) in rats produces pituitary-adrenal activation and a variety of "anxiogenic-like" effects. The present study was designed to explore the contribution of the peripheral pituitary-adrenocortical axis in mediating these CRF responses. Intraventricularly administered CRF produced suppression of responding in the conflict test and a marked locomotor activation. Neither behavioral effect was altered by the prior administration of dexamethasone in a dose that blocked pituitary-adrenal activation to CRF. These results support the hypothesis that behavioral effects of CRF are mediated by its action at central sites and not via an action on the pituitary-adrenocortical system.     

Parasitism in diversified agroecosystems: Phenology ofTrichogramma minutum [Hymenoptera: Trichogrammatidae]

Parasitism ofOstrinia nubilalis egg masses byTrichogramma minutum was observed in maize-bare ground monocultures and polycultures of maize/bean/squash and maize/clover. Parasitism rates were 1.9 times higher in monocultures than in polycultures; seasonal phenology of parasitism, however, was similar in both. Parasitism first occurred during the late whorl/early tassel stage of maize; peak parasitism occurred during the mid to late tassel stage, and then dropped off rapidly. We speculate that direct predation of egg masses, and ammensal preemptive competition for egg masses byColeomegilla maculata may have contributed to the decline in parasitism rates in both monocultures and polycultures during the latter part of the season.      

Model misspecification and multipoint linkage analysis.

Pairwise linkage analysis is robust to genetic model misspecification provided dominance is correctly specified, the primary effect being inflation of the recombination fraction. By contrast, we show that multipoint analysis under misspecified models is not robust when a putative disease locus is placed between close flanking markers, with potentially spuriously negative multipoint lod scores being produced. The problem is due to incorrect attribution of segregation of a disease allele and the consequent conclusion of (unlikely) double crossovers between flanking markers. As a possible solution, we propose the use of high disease allele frequencies, as this allows probabilistically for nonsegregation (through parental homozygosity or dual matings). We show analytically and through analysis of pedigree data simulated under a two-locus heterogeneity model that using a disease allele frequency of 0.05 in the dominant case and 0.25 in the recessive case is quite robust in producing positive multipoint lod scores with close flanking markers across a broad range of conditions including varying allele frequencies, epistasis, genetic heterogeneity and phenocopies.     

A note on Hardy-Weinberg equilibrium of VNTR data by using the Federal Bureau of Investigation''s fixed-bin method.

To fully utilize the information of VNTR data for forensic inference, the probability of observing the matching suspect and evidentiary profile in a reference population is estimated, usually by assuming independence of alleles within and between loci. This assumption has been challenged on the basis of the observation that there is frequently an excess of single-band phenotypes (SBP) in forensic data bases, which could indicate lack of independence. Nevertheless, another explanation is that the excess SBP are artifacts of laboratory methods. In this report we examine the excess of SBP for three VNTR loci studied by the FBI (D17S79 and D2S44, for blacks, and D14S13, for Caucasians). The FBI claims that the excess is due to the effect of null alleles; the null alleles are suspected to be too small to be detected. We estimate the frequency of null alleles for two loci (D17S79 and D14S13) by comparing, for these loci, the data from the FBI data base and the data from the Lifecodes data base. These comparisons yield information on small fragments because Lifecodes uses the restriction enzyme PstI, which yields larger fragments than does HaeIII, which the FBI uses. For D17S79 in blacks, we estimate a null allele frequency of 4.4%, and, for D14S13 in Caucasians, we estimate a frequency of 3.0%. The null-allele frequency for D2S44 in blacks is derived similarly, again being based on analyses of DNA cut with HaeIII and PstI; our estimate of the null-allele frequency for this locus is 1.5%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mode of inheritance of nonsyndromic cleft lip with or without cleft palate: a reanalysis.

Nonsyndromic cleft lip with or without cleft palate (CL +/- P) is traditionally recognized as a multifactorial threshold trait (MFT). Recently, however, evidence for the involvement of a major gene in the etiology of CL +/- P has been reported. To assess the potential for major-gene involvement in the etiology of this trait, familial recurrence patterns from several family studies of CL +/- P were reanalyzed. The recurrence patterns in first-degree relatives of CL +/- P probands were found to be compatible with the expectations for either an MFT or a generalized single-major-locus (gSML) trait. The use of multiple thresholds based on proband sex, defect bilaterality, or palatal involvement did not help to discriminate between these models. However, the pattern of recurrence among MZ twins and more remote relatives of CL +/- P probands is not consistent with gSML inheritance but is compatible with either an MFT model or a model specifying multiple interacting loci. For such a model, no single locus can account for more than a sixfold increase in risk to first-degree relatives. These findings have important implications with regard to the feasibility of detecting linkage to loci conferring susceptibility to CL +/- P.     

HPAC,a new human glucocorticoid-sensitive pancreatic ductal adenocarcinoma cell line

Summary A new human pancreatic cancer (HPAC) cell line was established from a nude mouse xenograft (CAP) of a primary human pancreatic ductal adenocarcinoma. In culture, HPAC cells form monolayers of morphologically heterogenous, polar epithelial cells, which synthesize carcinoembryonic antigen, CA 19-9, CA-125, cytokeratins, antigens for DU-PAN-2, HMFG1, and AUA1, but do not express chromogranin A or vimentin indicative of their pancreatic ductal epithelial cell character. In the presence of serum, HPAC cell DNA synthesis was stimulated by insulin, insulin growth factor-I, epidermal growth factor, and TGF-α but inhibited by physiologic concentrations of hydrocortisone and dexamethasone. Dose-dependent inhibition of DNA synthesis was limited to steroids with glucocorticoid activity. The inhibitory effect of dexamethasone was abolished by the glucocorticoid antagonist RU 38486. Binding of [³H]dexamethasone to cytosolic proteins was specific and saturable at 4° C. Scatchard analysis of binding data demonstrated a single class of high-affinity binding sites (K_d=3.8±0.9 nM; B_max=523±128 fmol/mg protein). Western blot analysis revealed a major protein band that migrated at a M_r of 96 kDa. Northern blot analysis identified an mRNA of approximately 7 kilobases which hybridized with a specific glucocorticoid receptor complementary DNA probe (OB7). These findings support a role for glucocorticoids in the regulation of human malignant pancreatic cell function.