A sex-specific test of selection in utero

We find support for the hypothesis that changes in the monthly odds of a twin among live-born males predict subsequent and opposite changes in the odds of a twin among live-born females. The hypothesis arises from the long standing argument that natural selection has conserved mechanisms by which pregnant women in stressed populations spontaneously abort fetuses least likely to yield grandchildren. Previous attempts to empirically test this argument focus almost entirely on males. We contribute to the literature by showing that, consistent with the logic of natural selection, maternal adaptations to environmental changes likely have effects on the survival of both male and female conceptuses and fetuses.     

Primary Succession on a Hawaiian Dryland Chronosequence

We used measurements from airborne imaging spectroscopy and LiDAR to quantify the biophysical structure and composition of vegetation on a dryland substrate age gradient in Hawaii. Both vertical stature and species composition changed during primary succession, and reveal a progressive increase in vertical stature on younger substrates followed by a collapse on Pleistocene-aged flows. Tall-stature Metrosideros polymorpha woodlands dominated on the youngest substrates (hundreds of years), and were replaced by the tall-stature endemic tree species Myoporum sandwicense and Sophora chrysophylla on intermediate-aged flows (thousands of years). The oldest substrates (tens of thousands of years) were dominated by the short-stature native shrub Dodonaea viscosa and endemic grass Eragrostis atropioides. We excavated 18 macroscopic charcoal fragments from Pleistocene-aged substrates. Mean radiocarbon age was 2,002 years and ranged from < 200 to 7,730. Genus identities from four fragments indicate that Osteomeles spp. or M. polymorpha once occupied the Pleistocene-aged substrates, but neither of these species is found there today. These findings indicate the existence of fires before humans are known to have occupied the Hawaiian archipelago, and demonstrate that a collapse in vertical stature is prevalent on the oldest substrates. This work contributes to our understanding of prehistoric fires in shaping the trajectory of primary succession in Hawaiian drylands.     

Direction of locomotion in clones of non-neoplastic fibroblasts and their neoplastic derivatives

The locomotion of cloned mouse fibroblasts, non-neoplastic and their spontaneously transformed neoplastic derivatives was compared by means of cinephotomicrography. The spontaneous transformants grow as invasive transplantable sarcomas, whereas the non-neoplastic fail to grow as tumors, and do not show the diagnostic characteristics of neoplastic cells in culture; these include certain morphologic alterations, growth in soft agar, and susceptibility to killing by activated macrophages. The non-neoplastic cells tended to maintain the same direction of locomotion in sequential 2.5 h periods, whereas the neoplastic cells did not. Thus, cells in all non-neoplastic lines exhibited a “persisten” walk while cells from the neoplastic lines had a random pattern of locomotion. No relationship between cell density and randomness of locomotion was observed, and the non-neoplastic cells appeared to grow as rapidly as the neoplastic cells. However, the neoplastic cells had higher rates of locomotion possibly associated with their invasive potential in vivo. The deficient amount of lamellar cytoplasm in the neoplastic cells and the high migration rate may account for their random pattern of locomotion.     

Identification of metabolites of phenylacetic acid in rat brain by plasma desorption mass spectrometry

Mass spectra of acyl hydroxamates may be obtained directly, without prior derivatization or gas chromatography, by the new technique of plasma desorption mass spectrometry. Authentic alkyl and aryl hydroxamates showed the expected protonated molecular ions when isobutane was used as the carrier gas. Advantage was taken of this novel technique to identify phenylacetyl-CoA and phenylbutyric acid in brain extracts obtained from young rats after a loading dose of phenylacetic acid. The formation of these metabolic products lends strong support to our suggestion that brain dysfunction induced by phenylacetic acid in experimental phenylketonuria may be due to decreased availability of CoA and acetyl-CoA in the rapidly developing brain.     

Ethylmorphine-N-demethylation by liver homogenate of newborn and adult rats; Enzyme kinetics and age course of Vmax and Km1.

Optimum incubation conditions for determination of ethylmorphine-N-demethylation with newborn and adult rat liver homogenate have been determined: 1 ml 1:20 liver homogenate in 1.15% KCl, 1 ml 0.1 M phosphate buffer with ethylmorphine, NADP, and glucose-6-P, final concentrations 10, 0.33 and 5 mM, respectively, no nicotinamide, no MgCl2, 1 ml 0.5 M phosphate buffer; 3 ml final volume, 20 min incubation time. With both age groups NADH increases the activity to the same extent. With NADPH, saturation could be achieved only with newborn liver, but not with adult liver homogenate. Postnatally, the activity increases about fivefold, with a break at the 10th day of life. The Lineweaver-Burk plot was linear with newborn liver homogenate, whereas for all other age groups the graphs showed an angle. Statistical analysis pointed out that a two-enzyme model fits the experimental data only insignificantly better than a one-enzyme model. From other experimental evidence and manifold reproduction without any exception of these results, however, it may be concluded that there are different monooxygenases which show different affinities towards one substrate (ethylmorphine) and which show different developmental patterns.