Transfer of Cesium from the Xylem to the Phloem in the Stem of Wheat

Steam-girdling experiments with detached wheat shoots showed that cesium was eliminated from the xylem sap and loaded into the phloem during acropetal transport. This transfer is important for the accumulation of cesium (especially also of the radiopollutants ¹³⁴Cs and ¹³⁷Cs) in maturing wheat grains.     

Circuit Integration Initiation of New Hippocampal Neurons in the Adult Brain

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Exceptional growth rates of captive loggerhead sea turtles,Caretta caretta

Twelve loggerhead sea turtle hatchlings (Caretta caretta) were removed from a nest site (A) at the Back Bay National Wildlife Refuge (U.S. Fish and Wildlife Service), Virginia Beach, VA. Hatchlings were distributed among study participants, and raised in captivity for a period of two years. Growth of the loggerheads was recorded weekly by straight-line caliper measurements of carapace lengths as well as measurements of total weights. Growth rates from the present study were much greater than those measured in previous studies. Mean weights for Nest A turtles at 1.5 years ranged from 10.3 to 17.6 kg, with one exceptional individual reaching 20.0 kg. The data from this study provide new insights into the early growth potential of loggerhead sea turtles. How this accelerated development may affect sexual maturity and post-release viability remain to be determined. © 1993 Wiley-Liss, Inc.     

The Effect of Ribosome Assembly Cofactors on In Vitro 30S Subunit Reconstitution

Ribosome biogenesis is facilitated by a growing list of assembly cofactors, including helicases, GTPases, chaperones, and other proteins, but the specific functions of many of these assembly cofactors are still unclear. The effect of three assembly cofactors on 30S ribosome assembly was determined in vitro using a previously developed mass-spectrometry-based method that monitors the rRNA binding kinetics of ribosomal proteins. The essential GTPase Era caused several late-binding proteins to bind rRNA faster when included in a 30S reconstitution. RimP enabled faster binding of S9 and S19 and inhibited the binding of S12 and S13, perhaps by blocking those proteins' binding sites. RimM caused proteins S5 and S12 to bind dramatically faster. These quantitative kinetic data provide important clues about the roles of these assembly cofactors in the mechanism of 30S biogenesis.     

Juvenile hormone drives the maturation of spontaneous mushroom body neural activity and learned behavior

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Purification and characterization of tubulin from ginkgo pollen

 Tubulin was purified by a combination of acetone powder preparation, DEAE Sephadex A-50 chromatography, Sephacryl S-300 gel filtration, and Mono Q anion exchange chromatography from the pollen of ginkgo (Ginkgo biloba L.), a typical gymnosperm. The average yield of tubulin is 2 mg per 100 g of pollen grain. The purified tubulin is electrophoretically homogeneous. It seems to be composed of two subunits on SDS-PAGE and is resolved as two major spots on two-dimensional electrophoresis, preliminarily indicating that there are no obvious tubulin isotypes in ginkgo pollen. The apparent molecular weights of the two subunits are about 54 kDa and 52 kDa respectively, estimated from the SDS-PAGE. It was also demonstrated that tubulin from ginkgo pollen is immunochemically related to animal brain tubulin, and the purified tubulin was polymerized to microtubular aggregates in the presence of taxol and GTP in vitro. Received: 13 April 1996 / Revision accepted: 24 March 1997     

Brachymesophalangia V in Hottentot and “Cape Colored” children in Namibia (South West Africa) and South Africa

In order to determine the incidence of Brachymesophalangia V, an inspectional and metrical analysis was made of radiographs of 67 Nama-speaking Hottentots aged 2 to 17.5 years, and 210 Rehoboth Basters (in Namibia) and Cape Colored children (near Cape Town) aged 1.5 to 21 years. None of the children displayed cone-shaped epiphysis or early union, and none showed Brachymesophalangia V. It was confirmed that the incidence of Brachymesophalangia V is considerably higher in Mongoloid populations than in Caucasoid or Negroid groups, including Hottentots.     

Towards the reconstruction of the Holocene vegetation history of Lower Provence: two new pollen profiles from Marais des Baux

Two new¹⁴C-dated Holocene pollen profiles from Marais des Baux, Bouches-du-Rhône, France, are presented. The record begins in the Younger Dryas, when the vegetation consisted mainly of grasses and mugwort (Artemisia). The Preboreal was marked by a transitory expansion of pine forests and was followed by the establishment of a rich deciduous oak-forest that included hazel (Corylus) and elm (Ulmus). During the Boreal, hazel played a dominant role within the oak-forest. The oak forests, which includedQuercus ilex, achieved a major expansion during the Atlantic period. The Subboreal was characterised by the regional establishment of, firstly, fir (Abies) and then beech (Fagus). The spread and expansion of beech coincides with the first clear evidence for farming. Agricultural activities brought about the decline of deciduous oak-forest. During the Subatlantic, forests in the vicinity of Marais des Baux were cleared for farming. Cereal growing, which included rye cultivation, was of considerable importance. Three noteworthy characteristics that serve to differentiate the Holocene vegetation history of the low-lying Provence region from other French regions are as follows: 1) the early establishment (from the onset of Preboreal) of low altitude mixed forest; 2) the expansion during the Subboreal of fir and beech in low altitude areas with a Mediterranean climate and, 3) the exceptional taxonomic richness of the pollen assemblages (120 identified taxa) and the presence of borealalpine and Euro-Siberian taxa that no longer exist in Lower Provence.