Human peripheral blood mononuclear cells: ; Inhibition of biotin transport by reversible competition with pantothenic acid is quantitatively minor

A transporter present in intestinal cells and in choriocarcinoma cells has been shown to transport both pantothenic acid and biotin at similar transporter affinities. However, the concentration of pantothenic acid in most foods and biological fluids is approximately 200 times the concentration of biotin; theoretically, pantothenic acid might substantially reduce biotin transport via competition. In the present study, we sought to determine whether pantothenic acid reduces biotin transport by the biotin transporter in peripheral blood mononuclear cells (PBMC). PBMC were isolated from human blood by gradient centrifugation. Incubations with [(3)H]biotin and pantothenic acid were conducted at physiologic concentrations. Intracellular [(3)H]biotin was quantified after washing by liquid scintillation counting. Pantothenic acid at 10 to 1,000 nmol/L reduced biotin (475 pmol/L) uptake by less than 12% (P < 0.05). Based on Lineweaver-Burk plots, the competition was reversible. Several structural analogs of pantothenic acid at 1,000 nmol/L reduced biotin transport by only 7 to 15% (P = 0.13). No pattern of molecular structure required for recognition by the transporter was apparent. Extracellular pantothenic acid did not affect biotin efflux from [(3)H]biotin-loaded PBMC (P > 0.05), suggesting that countertransport of extracellular pantothenic acid and intracellular biotin does not increase biotin efflux from PBMC. We conclude that the physiologic effects of pantothenic acid on the transport of biotin in PBMC are likely to be quantitatively minor.     

Synergistic inhibition of carboxypeptidase A by zinc ion and imidazole

Zinc ion in solution yields a 560-fold enhancement in the kinetic inhibition of carboxypeptidase A by the simple heterocycle imidazole, behavior attributed to formation of a ternary complex of the three species. However, the effect is partially negated by formation of less-inhibitory Zn2+(C3H4N2)2-4 coordination complexes, providing for the enzyme an anomalous profile of catalytic rate versus imidazole concentration.     

Co-existence of clpB and clpC in the Bacillaceae

The gene encoding ClpC in Bacillus anthracis was amplified from the chromosome by polymerase chain reaction using degenerate oligonucleotide primers. These primers also amplified a second DNA fragment identified as a clpB homolog. Both genes were suggested to be functional. Contrary to Bacillus subtilis which possesses clpC but not clpB, many Bacillus species were found to harbor both clpC and clpB. We also found that Clostridium strains could possess clpB, clpC, or both. All the Gram-negative strains tested had clpB only.     

Four thousand years of plant exploitation in the Lake Chad Basin (Nigeria), part III: plant impressions in potsherds from the Final Stone Age Gajiganna Culture*

Late Holocene climatic changes caused a large scale regression of the Lake Chad shoreline followed by an expansion of settlements into previously unexplored territories. Numerous Final Stone Age sites of the Gajiganna Culture (1,800 to 800 b.c.) in the Lake Chad Basin (northeast Nigeria) yielded plant impressions in potsherds. The ceramics of Phase I (1,800–1,400 b.c.) were mineral tempered, and plant impressions, mainly of Paniceae, were caused only by incidental inclusion. In contrast, a considerable number of the sherds from Phase II (1,500–800 b.c.) were intentionally tempered with chaff derived from domesticated pearl millet (Pennisetum glaucum), wild Paniceae and wild rice species (Oryza cf. barthii and O. cf. longistaminata). This plant spectrum suggests the exploitation of the wet wild areas, and also the cultivation of pearl millet on sandy soils. The evidence suggests that agricultural practices were established late and were introduced from elsewhere. During the time of seasonally occupied sites in Phase I, the subsistence strategy was based on herding, fishing, and gathering, while in Phase II there are signs of permanent settlements and agriculture. The evidence from the plant impressions indicates that in the Final Stone Age Gajiganna Culture around 1,000–800 b.c., pearl millet became well established while the gathering of wild millets and rice was still practised.*Klee et al. (2000), Zach and Klee (2003)     

Proteomic approach: Identification of <Emphasis Type="Italic">Medicago truncatula</Emphasis> proteins induced in roots after infection with the pathogenic oomycete <Emphasis Type="Italic">Aphanomyces euteiches</Emphasis>

The legume root rot disease caused by the oomycete pathogen Aphanomyces euteiches is one major yield reducing factor in legume crop production. A comparative proteomic approach was carried out in order to identify proteins of the model legume Medicago truncatula which are regulated after an infection with A. euteiches. Several proteins were identified by two dimensional gel electrophoresis to be differentially expressed after pathogen challenge. Densitometric evaluation of expression values showed different regulation during the time-course analysed. Proteins regulated during the infection were identified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). Among the differentially expressed proteins, two encoded putative cell wall proteins and two were designated as small heat shock proteins. Furthermore, an isoform of the chalcone-O-methyltransferase was found to be increased in infected roots. The majority of induced proteins belonged to the family of class 10 of pathogenesis related proteins (PR10). Previously, various PR10-like proteins have been shown to be regulated by general stress or abscisic acid (ABA). Therefore, these proteins were further investigated concerning their regulation in response to drought stress and exogenous ABA-application. Complex regulation patterns were identified: three of the A. euteiches-induced PR10-like proteins were also induced by exogenous ABA- but none of them is induced after drought stress. In contrast, three of these proteins are down-regulated by drought stress. Hence, the strong expression of different PR10-family members and their regulation profiles indicates that this set of proteins plays a major role during root adaptations to various stress conditions.     

Gamma carbonic anhydrase like complex interact with plant mitochondrial complex I

We report the identification by two hybrid screens of two novel similar proteins, called Arabidopsis thaliana gamma carbonic anhydrase like1 and 2 (AtCAL1 and AtCAL2), that interact specifically with putative Arabidopsis thaliana gamma Carbonic Anhydrase (AtCA) proteins in plant mitochondria. The interaction region that was located in the N-terminal 150 amino acids of mature AtCA and AtCA like proteins represents a new interaction domain. In vitro experiments indicate that these proteins are imported into mitochondria and are associated with mitochondrial complex I as AtCAs. All plant species analyzed contain both AtCA and AtCAL sequences indicating that these genes were conserved throughout plant evolution. Structural modeling of AtCAL sequences show a deviation of functionally important active site residues with respect to CAs but could form active interfaces in the interaction with AtCAs. We postulate a CA complex tightly associated to plant mitochondrial complex.     

Novelties of conception in insectivorous mammals (Lipotyphla), particularly shrews

In the order Lipotyphla (Insectivora), certain reproductive features differ quite distinctly from the eutherian norms, and are of interest with regard to the evolution of mammalian gamete function and perhaps for questions of lipotyphlan phylogeny. As seen in one or more members of five lipotyphlan families (shrews, moles, hedgehogs, golden moles, tenrecs), these features can involve the configuration of the male tract including the penis, the morphology of the sperm head, the anatomy of the oviduct and the patterns of sperm transport within it, the character of the cumulus oophorus, and the way in which fertilising spermatozoa interact with the eggs. However, the picture is by no means uniform within the order. Reproductive idiosyncrasies occur variously in the different lipotyphlan families, and appear consistently and strikingly in shrews--the group studied most extensively. Compared to the patterns in most Eutheria, the most interesting anomalies in soricids include (a) the regulation of sperm transport to the site of fertilisation by oviduct crypts, whose arrangement can vary even according to species, (b) a circumscribed matrix-free cumulus oophorus that appears essential for fertilisation as the inducer of the acrosome reaction, (c) barbs on the acrosome-reacted sperm head by which it may attach to the zona pellucida. With regard to the bearing such reproductive traits might have on lipotyphlan systematics, the African mouse shrew (Myosorex varius) displays a mix of traits that characterize either crocidurine or soricine shrews, consistent with the proposal that it belongs in a more primitive tribe, Myosoricinae, or subfamily, the Crocidosoricinae, from which the crocidurine and soricine lines probably evolved. Moreover, although elephant shrews are assigned now to a separate order (Macroscelidea), they display several of the unusual reproductive features seen in lipotyphlans, particularly in chrysochlorids and tenrecs. On the other hand, if used as a phylogenetic yardstick, none of the reproductive features described serves to define the Lipotyphla as classically constituted within one order, nor necessarily all the relationships suggested by recent sequencing studies of nuclear and mitochondrial genes.     

d-matrix – database exploration,visualization and analysis

Background  

Motivated by a biomedical database set up by our group, we aimed to develop a generic database front-end with embedded knowledge discovery and analysis features. A major focus was the human-oriented representation of the data and the enabling of a closed circle of data query, exploration, visualization and analysis.     

ER export: call 14-3-3

Forward transport of proteins from the ER to the plasma membrane requires escape from the ER's retention machinery. Recent studies suggest that 14-3-3 proteins may mediate ER export of potassium channels destined for the plasma membrane by interfering with dibasic-motif-mediated retention.