Detection of low-grade mosaicism in fetal cells isolated from maternal blood

Recovering and analysing fetal erythrocytes from maternal blood is being pursued for non-invasive prenatal genetic diagnosis. We report the observation of 46, XY/47, XXY mosaicism in fetal cells from a woman whose first-trimester chorionic villus sampling (CVS) initially showed only 46, XY. Only after exhaustive (500 cells) analysis were four XXY cells found in cultured villi.     

Gap junctions in freeze-fractured membranes of the arachnoid mater

The Science of Nature -     

Degradation of N,N'-dibutylurea (DBU) in soils treated with only DBU and DBU-fortified benlate fungicides

N,N'-dibutylurea (DBU) is a breakdown product of benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazole carbamate], the active ingredient in Benlate fungicides, and has been proposed to cause crop damage after the use of Benlate 50 DF fungicide (DuPont, Wilmington, DE). Our research focused on DBU persistence after application into soil. We assessed DBU persistence on direct application of DBU (carbonyl-(14)C) at two concentrations (0.08 and 0.8 microg DBU kg(-1)) to seven soils and two potting mixes in soil microcosms incubated at various combinations of soil water potential (-0.03 or -0.1 MPa) and temperature (23, 33, 44 degrees C). For two soils at a subset of treatment variables we assessed DBU persistence in the presence of Benlate DF and SP fungicide formulations. Parent compounds, metabolites, and (14)CO(2) were tracked using chromatographic analysis with radioassay and UV detection, liquid scintillation counting, and post-extraction oxidation of the soil. DBU degradation was primarily microbial and for most soil-treatment combinations, half-lives were less than 2 wk. DBU degradation was retarded at the lower soil water potential and enhanced at 33 degrees C. In the presence of the formulation, DBU degradation was slower for one soil type. The longest half-life observed in any case was less than 7 wk; therefore, long-term persistence of DBU applied to soils through a Benlate application is very unlikely.     

Cytological sexing of cetacea

A biopsy dart, that can be shot from a gun or crossbow, was developed to obtain skin of whales at sea. Determination of sex was found possible by staining and locating sex chromatin bodies in the nuclei of female skin cells. This procedure will be useful in many types of field studies on whales.     

Mosaicism for trisomy 12: Four cases with varying outcomes

Trisomy 12 observed in chorionic villus sampling (CVS) may reflect generalized mosaicism or indicate mosaicism confined to only the placenta. In this report, four cases of trisomy 12 observed in CVS or cultured placental biopsies with varying outcomes are presented. Seven dinucleotide repeat polymorphisms for chromosome 12 were used to determine the chromosome 12 origins in the fetus or child and to delineate the mechanism(s) that gave rise to the trisomy. In two cases (cases A and C), the mosaicism was confined to the placenta, resulting in normal liveborns. Although, in one case, the molecular results suggested an apparent duplication of one paternal chromosome 12 in the placenta, normal biparental inheritance was found in the diploid fetal cell line in both cases. In two other cases (cases B and D), trisomy 12 was observed in both extraembryonic and fetal tissues. In one of these pregnancies, a child was born by Caesarean section at 37 weeks because of intrauterine growth retardation and oligohydramnios, and resulted in neonatal death. Molecular markers and fluorescence in situ hybridization (FISH) revealed low-level trisomy 12 mosaicism in the spleen. In the fourth case, fetal abnormalities were detected on ultrasound and low-level trisomy 12 mosaicism was observed in amniotic fluid cells using conventional cytogenetics and FISH. Molecular markers revealed a maternal meiosis I non-disjunction of chromosome 12 in DNA from a cultured placental biopsy. Although predicting the outcomes of pregnancies involving confined placental mosaicism remains difficult, molecular techniques are valuable tools for distinguishing uniparental from biparental disomy and mechanisms of mosaicism.     

Tail size and female choice in the guppy (Poecilia reticulata)

Summary Under laboratory conditions, female guppies demonstrate a clear preference for males with larger tails, and this preference translates into enhanced reproductive fitness for these males. Females also prefer males with higher display rates, a behavior which appears to be linked to tail size, but which can be experimentally disassociated. This appears to be a case of female-choice sexual selection.     

Flower color influences insect visitation in alpine New Zealand

Despite a long-standing belief that insect pollinators can select for certain flower colors, there are few experimental demonstrations that free-flying insects choose between natural flowers based on color. We investigated responses of insect visitors to experimental manipulations of flower color in the New Zealand alpine. Native syrphid flies (Allograpta and Platycheirus) and solitary bees (Hylaeus and Leioproctus) showed distinct preferences for visiting certain flower species. These responses were determined, in part, by flower color, as insects also responded to experimental manipulations of visible petal color in 7 out of 11 tests with different combinations of flower species and insect type. When preferences were detected, syrphid flies chose yellow over white petals regardless of flower species, whereas Hylaeus chose white over yellow Ourisia glandulosa. In some cases, the strength and direction of color preference depended on the context of other floral traits, in which case the response usually favored the familiar, normal combination of traits. Syrphid flies also visited in response to floral morphological traits but did not show preference based on UV reflectance. The unusually high preponderance of white flowers in the New Zealand alpine is not explained by complete generalization of flower color choice. Instead, the insect visitors show preferences based on color, including colors other than white, along with other floral traits. Furthermore, they can respond in complex ways to combinations of floral cues, suggesting that traits may act in nonadditive ways in determining pollinator visitation.     

Deposition of dust with active substances in pesticides from treated seeds in adjacent fields during drilling: disentangling the effects of various factors using an 8-year field experiment

Environmental Science and Pollution Research - The side effects from the use of plant protection products and their potential effects on non-target arthropods (NTAs) such as honey bees, other...     

Temperature adaptation in strains of the amphi-equatorial green alga Urospora penicilliformis (Acrosiphoniales): biogeographical implications

The temperature requirements for growth and the upper survival temperatures (UST's) of the amiphi-equatorial green alga Urospora penicilliformis collected from several localities within its distribution area between 1986 and 1991 were determined. Ecotypic variation, both with regard to growth ranges and optima and to survival temperatures, was demonstrated. In the polar strains of U. penicilliformis, temperature growth ranges were narrower and the growth optima and UST's were at lower temperatures compared to cold-temperate strains. In particular, the polar strains grew between 0 and 15°C with optimal growth at 0 or 5°C, whereas the cold-temperate isolates grew between 0 and (15) 20°C with almost equal growth rates or a growth optimum between 5 and 15°C. The Arctic strains survived 23 to 24°C, and the Antarctic isolate only 19°C, while the UST's of the cold-temperate isolates were between (24) 25 to 26°C. The data strongly indicate that a cold water history of ca. 3 million yr in the Arctic can be sufficient for changes in the temperature growth ranges and optima as well as for small changes of UST as shown in the Arctic populations of U. penicilliformis. For stronger reduction of upper survival temperatures, longer time periods are necessary as exemplified in the isolate from Antarctica, where low temperatures have existed for at least 14 million yr. The significantly lower UST of the Antarctic strain, points to an early contact of the alga with the cold water of the Antarctic region and may indicate an origin of U. penicilliformis in the Southern Hemisphere. The UST's of the cold-temperate isolates (24 to 26°C) would have allowed a migration across the equator during Pleistocene lowerings of the seawater temperatures in the tropics. Growth, however, would not have been possible during the passage across the equator due to the narrow temperature-growth window. The nature of the geographical boundaries and the control of seasonal development of U. penicilliformis by the temperature conditions in the various geographical regions are discussed in relation to the present local temperature regime.