Tetrasomy 12p (Pallister-Killian syndrome): Ultrasound indicators and confirmation by interphase fish

Tetrasomy 12p (Pallister-Killian syndrome) is a mosaic aneuploidy syndrome in which the isochromosome is present in amniocytes with a much greater percentage than fetal lymphocytes. Two new cases identified by prenatal diagnosis are reported. Indications for prenatal diagnosis were advanced maternal age and fetal anomalies. The most consistent reported prenatal ultrasound findings for tetrasomy 12p include polyhydramnios with short femurs and a diaphragmatic hernia. Recognition of congenital malformation patterns prenatally may allow appropriate selection of tissue for chromosome analysis. Molecular cytogenetic analysis using fluorescence in situ hybridization was used retrospectively to confirm the presence of the isochromosome 12p in various formalin-fixed fetal tissues. The levels of mosaicism detected in fetal and placental tissues were lower than those detected prenatally.     

大型动物的种群恢复:大象种群增长的生态学效应

博茨瓦纳北部及其毗邻地区分布着世界上最大的非洲象种群(Loxodonta africana),而在100年前,由于过度捕猎,大象的种群数量极为稀少.     

Confirmation of CVS mosaicism in term placentae and high frequency of intrauterine growth retardation association with confined placental mosaicism

About 2 per cent of specimens from chorionic villus sampling (CVS) analysed either on direct preparation of cytotrophoblast cells or afterculture of mesenchymal stroma reveal confined placental mosaicism (CPM), most commonly involving chromosomal trisomy. A significantly higher rate of prenatal loss (22 per cent) as well as the presence of intrauterine growth retardation (IUGR) has been reported among pregnancies with CPM. To evaluate more precisely the effect of these aneuploid cell lines confined to the placenta on intrauterine fetal growth and fetal survival, we have studied 34 term placentae from pregnancies with CPM diagnosed on CVS and confirmed identical mosaicism in 17 of these placentae. There was a direct correlation between a high number of aneuploid cells present at CVS and a high likelihood of their detection in term placenta. Also, the proportion of aneuploid cells in the mosaic term placentae correlated with that observed in CVS specimens. Among 17 gestations with confirmed CPM at delivery, there were six cases of IUGR identified, five in liveborns and one associated with intrauterine death.     

Sources and concentrations of vascular plant material in sediments of Buzzards Bay,Massachusetts, USA

Samples of surface sediment from Buzzards Bay and creek sediment from Great Sippewissett Marsh were analyzed for lignin and stable carbon isotope composition in 1984. The lack of change in composition of lignins in detritus of Spartina alterniflora over two years of decomposition and similar aldehyde/acid ratios of lignin oxidation products of plant and sediment samples indicated minimal diagenesis of lignins in sediments. Remains of non-woody angiosperm tissues made up the bulk of the vascular plant debris in Great Sippewissett Marsh and Buzzards Bay sediments. These plant remains were evenly distributed over the sampling area in Buzzards Bay. Based on model calculations, salt marshes potentially contributed a significant fraction of the total amount of vascular plant debris in coastal marine sediments. The bulk of the organic matter in Buzzards Bay sediments, however, was derived from phytoplankton; vascular plant remains made up only 5 to 7% of the total amount of organic carbon in these sediments.     

Depth utilisation by breeding Adélie penguins,Pygoscelis adeliae,at Esperanza Bay,Antarctica

Miniature depth gauges were attached in December 1987 and January 1988 to Adélie penguins,Pygoscelis adeliae, breeding at Esperanza on the Antarctic Peninsula. Results from 34 birds showed that foraging penguins with eggs and with brooded and crèching chicks spent mean periods away from the nest of 96, 36 and 21 h, respectively, during which time means of 29.0 h (30%), 11.2 h (31%) and 2.7 h (13%), respectively, were spent under water at depths > 5 m. Time under water was positively correlated with time absent from nest. Maximum depth reached was 170 m but overall birds spent most time at shallower depths. Birds foraging for brooded chicks dived deeper than birds foraging for crèching chicks. Stomach-pumping indicated that the principal prey caught at this time was krill,Euphausia superba. Mean mass changes of adults during single foraging trips indicated that krill were caught at a mean rate of 7.2 g min^–1 spent under water.     

Macroinfaunal structure and effects of thermal discharges in a mesohaline habitat of Chesapeake Bay,near a Nuclear Power Plant

The soft-bottom macroinfauna of the Chesapeake Bay near the Calvert Cliffs Nuclear Power Plant, Maryland, USA, was studied quarterly in 1977. A total of 42,900 organisms distributed among 55 taxa was taken in 180 Smith-McIntyre grabs. Two communities and an ecotone between these two communities were identified in association with three sediment types: sand, sand-clay, and clay. Reproductive activities of 8 numerically dominant species are described. The macroinfauna at Calvert Cliffs was largely seasonal; species richness and organism abundances were lowest in late summer. The polychaetes Scolecolepides viridis and Heteromastus filiformis and the bivalves Macoma balthica and Mya arenaria were dominant in March-June. In September-December, the polychaetes Neanthes succinea, Paraprionospio pinnata, and Glycinde solitaria and the bivalve Gemma gemma became dominant. There were clear indications of differences associated with sediment types in total number of species, total number of individuals, and abundances of the dominant species. The shallower and intermediate habitats had higher sand-clay ratios, lower organic carbon contents, and larger numbers of organisms than the deeper clay habitat. Within each depth, no apparent detrimental effects caused by the thermal discharges on total number of species, total number of individuals, abundances of the dominant species, species diversity or evenness were found. Increased abundance was observed at the discharge stations for a few species, especially for Mya arenaria and N. succinea.     

Up-beat motion in swinging limbs: new insights into assessing movement in free-living aquatic vertebrates

A new system is presented for assessing the movement of animal limbs including, after suitable calibration, quantification of limb stroke frequency and amplitude, which may be used to derive limb angular velocity and acceleration. The system is based on use of an archival unit logging data from a Hall sensor, itself set to sense magnetic-field strength at frequencies of up to 30 Hz. Typically, the Hall sensor is placed on the animal body adjacent to the limb being monitored, while a small magnet is glued to the limb. Changes in limb position result in variation of the magnetic-field strength perceived by the sensor. Captive trials were successfully performed on a harbour seal (Phoca vitulina), an Australian sea lion (Neophoca cinerea) and a hawksbill turtle (Eretmochelys imbricata), as well as on 18 free-living Magellanic penguins (Spheniscus magellanicus). The unit performed well in almost all cases, illustrating that stroke frequency was relatively invariant in any species tending, however, to be higher in smaller animals and showing that the primary variance was manifest in stroke amplitude. As an example of the utility of the system, the importance of buoyancy was demonstrated in the penguins, which had longer glide phases and lower flipper beat amplitudes at greater depths, because body air was compressed, which reduced upthrust. The small size of the system (ca. 25 g in air) makes it suitable for a wide range of marine vertebrates. Potential problems of system sensitivity, the suitability of particular recording frequencies and the value of appropriate calibration are discussed.     

Pollution in the upland environment

As part of a study on the effects of pollutants on forests, a long-term monitoring programme has been operating at two sites (602 and 275 m above sea level (a.s.l.)) in Glentress Forest, south-east Scotland, since June 1987. At these sites, equipment has been recording 20-min data for weather parameters, and cloud and rain event frequency, duration and intensity. The chemical composition of bulk cloud and rainwater has been measured. Cloudwater detection and collection has been made using passive 'Harp wire' gauges (with a cross-sectional area of 0.047 m2) strung with polypropylene filament and having a typical collection efficiency of 29% when compared with independent measurements of windspeed and liquid water content. During 1988, the annual rainfall at the upper site was 1213 mm, occurring over 1776 h. The equivalent cloudwater deposition to a forest with a drag coefficient of 0.06 was estimated to be 375 mm over 1936 h. A 'typical cloud event' lasted 4.5 h and would deposit to forests at a rate of 0.2 mm h(-1). There were significantly higher loadings of suspended particulate material (> 0.2 microm) in cloudwater (mean 18.42, max. 94.5 mg litre(-1)) compared with rainwater (mean 2.6, max. 25.6 mg litre(-1)). There were similar differences in ion concentrations, e.g. for H+ in cloudwater (mean 163, max. 1259 microm) and in rainwater (mean 33, max. 262 microM). It is concluded that cloudwater deposition represents a major pathway for pollutant transfer to the upland environment, especially where the surface vegetation is efficient at capturing cloudwater, i.e. forests. The consequences of this increased pollutant loading to forests and water catchments are yet to be assessed.