A study of vasoactive intestinal polypeptide (VIP) stimulated intestinal fluid secretion in rat and its inhibition by indomethacin

4 groups of rats were studied under anaesthesia to assess the effect of VIP and the influence of the prostaglandin synthetase inhibitor indomethacin in isolated bowel loops. VIP produced a highly significant increase in the luminal fluid content and this was completely inhibited by addition of indomethacin.     

Radioimmunoassay of plasma progesterone,testosterone, total estrogens and immunoreactive gonadotropin in the nesting and non-nesting green sea turtle,Chelonia mydas (L.)

Summary Plasma progesterone, testosterone, total estrogens and immunoreactive gonadotropin were measured in nesting and non-nesting sea turtles,Chelonia mydas. Progesterone and gonadotropin concentrations were significantly higher in nesting than in non-nesting turtles, testosterone was not significantly different in either group and total estrogens appeared to be slightly higher in the nesting group.     

Electron microscopic observation of bacteria growing on the skin surface

Résumé Des observations au microscope électronique ont été faites sur des bacteries se développant à la surface de la peau. En utilisant la technique de fixation deRyter-Kellenberger, les auteurs ont obtenu bonne préservation des microorganismes, ce qui a permis l'étude de leur fine structure.

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Supported in part by grants from the Eli Lilly Co., Indianapolis, Indiana and the Upjohn Co., Kalamazoo, Michigan. — We are indebted to Drs.S. H. Black, E. Kellenberger andR. P. Williams for their valuable suggestions. — We are also grateful to MissS. Martin, MissN. Moreland and Mr.G. Adams for their technical assistance.     

Glycine,strychnine and retinal inhibition

Résumé L'injection intravitréenne de glycine (3 mg) chez le lapin entraîne l'abolition des potentiels oscillatoires de l'ERG moyenné photopique, phénomène réversible en 20–24 h. La glycine exerce un effet inhibiteur, qui est annulé par la strychnine en faible dose.     

Creatinine metabolism byClostridium welchii isolated from human faeces

Summary AClostridium welchii has been isolated from human faeces which can deaminate creatinine to N-methyl hydantoin. Evidence suggests the reaction is inducible since the rate of conversion is increased by growth of the organism in creatinine-rich media.     

Global hotspots of species richness are not congruent with endemism or threat

Biodiversity hotspots have a prominent role in conservation biology, but it remains controversial to what extent different types of hotspot are congruent. Previous studies were unable to provide a general answer because they used a single biodiversity index, were geographically restricted, compared areas of unequal size or did not quantitatively compare hotspot types. Here we use a new global database on the breeding distribution of all known extant bird species to test for congruence across three types of hotspot. We demonstrate that hotspots of species richness, threat and endemism do not show the same geographical distribution. Only 2.5% of hotspot areas are common to all three aspects of diversity, with over 80% of hotspots being idiosyncratic. More generally, there is a surprisingly low overall congruence of biodiversity indices, with any one index explaining less than 24% of variation in the other indices. These results suggest that, even within a single taxonomic class, different mechanisms are responsible for the origin and maintenance of different aspects of diversity. Consequently, the different types of hotspots also vary greatly in their utility as conservation tools.     

Active foundering of a continental arc root beneath the southern Sierra Nevada in California

Seismic data provide images of crust-mantle interactions during ongoing removal of the dense batholithic root beneath the southern Sierra Nevada mountains in California. The removal appears to have initiated between 10 and 3 Myr ago with a Rayleigh-Taylor-type instability, but with a pronounced asymmetric flow into a mantle downwelling (drip) beneath the adjacent Great Valley. A nearly horizontal shear zone accommodated the detachment of the ultramafic root from its granitoid batholith. With continuing flow into the mantle drip, viscous drag at the base of the remaining approximately 35-km-thick crust has thickened the crust by approximately 7 km in a narrow welt beneath the western flank of the range. Adjacent to the welt and at the top of the drip, a V-shaped cone of crust is being dragged down tens of kilometres into the core of the mantle drip, causing the disappearance of the Moho in the seismic images. Viscous coupling between the crust and mantle is therefore apparently driving present-day surface subsidence.     

Mid-depth recirculation observed in the interior Labrador and Irminger seas by direct velocity measurements

The Labrador Sea is one of the sites where convection exports surface water to the deep ocean in winter as part of the thermohaline circulation. Labrador Sea water is characteristically cold and fresh, and it can be traced at intermediate depths (500-2,000 m) across the North Atlantic Ocean, to the south and to the east of the Labrador Sea. Widespread observations of the ocean currents that lead to this distribution of Labrador Sea water have, however, been difficult and therefore scarce. We have used more than 200 subsurface floats to measure directly basin-wide horizontal velocities at various depths in the Labrador and Irminger seas. We observe unanticipated recirculations of the mid-depth (approximately 700 m) cyclonic boundary currents in both basins, leading to an anticyclonic flow in the interior of the Labrador basin. About 40% of the floats from the region of deep convection left the basin within one year and were rapidly transported in the anticyclonic flow to the Irminger basin, and also eastwards into the subpolar gyre. Surprisingly, the float tracks did not clearly depict the deep western boundary current, which is the expected main pathway of Labrador Sea water in the thermohaline circulation. Rather, the flow along the boundary near Flemish Cap is dominated by eddies that transport water offshore. Our detailed observations of the velocity structure with a high data coverage suggest that we may have to revise our picture of the formation and spreading of Labrador Sea water, and future studies with similar instrumentation will allow new insights on the intermediate depth ocean circulation.     

A study of vasoactive intestinal polypeptide (VIP) stimulated intestinal fluid secretion in rat and its inhibition by indomethacin

Summary 4 groups of rats were studied under anaesthesia to assess the effect of VIP and the influence of the prostaglandin synthetase inhibitor indomethacin in isolated bowel loops. VIP produced a highly significant increase in the luminal fluid content and this was completely inhibited by addition of indomethacin.