Amazonian biodiversity: assessing conservation priorities with taxonomic data

Data from 3991 records of museum collections representing 421 species of plants, arthropods, amphibians, fish, and primates were analyzed with GIS to identify areas of high species diversity and endemism in Amazonia. Of the 472 1 × 1° grid cells in Amazonia, only nine cells are included in the highest species diversity category (43–67 total species) and nine in the highest endemic species diversity category (4–13 endemic species). Over one quarter of the grid cells have no museum records of any of the organisms in our study. Little correspondence exists between the centers of species diversity identified by our collections-based data and those areas recommended for conservation in an earlier qualitative study of Amazonian biodiversity. Museum collections can play a vital role in identifying species-rich areas for potential conservation in Amazonia, but a concerted and structured effort to increase the number and distribution of collections is needed to take maximum advantage of the information they contain.     

Analysis of the effects of snake venom proteinases on the activity of human plasma C1 esterase inhibitor, alpha 1-antichymotrypsin and alpha 2-antiplasmin

Incubation of C1 esterase inhibitor with Crotalid, Viperid and Colubrid snake venoms resulted in enzymatic inactivation of the inhibitor. Intact inhibitor (104 kDa) was converted into an active intermediate species of 89 kDa and then a further cleavage resulted in formation of an 86-kDa inactive inhibitor. In contrast, C1 esterase inhibitor did not lose activity during incubation with Elapid venoms; however, the intact inhibitor was gradually converted to an active species of 89 kDa during the incubation. Human alpha 1-antichymotrypsin was inactivated by all venoms tested, including those from the Elapid family. The 67-kDa intact inhibitor was converted by the venom proteinases to an inactive 63-kDa form. The results suggest that this acute-phase plasma protein is readily susceptible to inactivation by venom proteinases. Human alpha 2-antiplasmin (68 kDa) was cleaved to form a 61-kDa active intermediate, which then underwent a second cleavage to produce an inactive 53-kDa product. Elapid venoms had no effect on alpha 2-antiplasmin activity and did not cleave this inhibitor. All inhibitors were inactivated with catalytic amounts of venom proteinases. No stable proteinase-proteinase inhibitor complexes were detected, and no random proteolysis of the inhibitors occurred.     

Distinct functions of maternal and somatic Pat1 protein paralogs

We previously identified Xenopus Pat1a (P100) as a member of the maternal CPEB RNP complex, whose components resemble those of P-(rocessing) bodies, and which is implicated in translational control in Xenopus oocytes. Database searches have identified Pat1a proteins in other vertebrates, as well as paralogous Pat1b proteins. Here we characterize Pat1 proteins, which have no readily discernable sequence features, in Xenopus oocytes, eggs, and early embryos and in human tissue culture cells. xPat1a and 1b have essentially mutually exclusive expression patterns in oogenesis and embryogenesis. xPat1a is degraded during meiotic maturation, via PEST-like regions, while xPat1b mRNA is translationally activated at GVBD by cytoplasmic polyadenylation. Pat1 proteins bind RNA in vitro, via a central domain, with a preference for G-rich sequences, including the NRAS 5′ UTR G-quadruplex-forming sequence. When tethered to reporter mRNA, both Pat proteins repress translation in oocytes. Indeed, both epitope-tagged proteins interact with the same components of the CPEB RNP complex, including CPEB, Xp54, eIF4E1b, Rap55B, and ePAB. However, examining endogenous protein interactions, we find that in oocytes only xPat1a is a bona fide component of the CPEB RNP, and that xPat1b resides in a separate large complex. In tissue culture cells, hPat1b localizes to P-bodies, while mPat1a-GFP is either found weakly in P-bodies or disperses P-bodies in a dominant-negative fashion. Altogether we conclude that Pat1a and Pat1b proteins have distinct functions, mediated in separate complexes. Pat1a is a translational repressor in oocytes in a CPEB-containing complex, and Pat1b is a component of P-bodies in somatic cells.     

Halothane inhibits the neurotoxin stimulated [14C]guanidinium influx through 'silent' sodium channels in rat glioma C6 cells

We have investigated the effect of pharmacological agents on [14C]guanidinium ion influx through sodium channels in C6 rat glioma and N18 mouse neuroblastoma cells. The sodium channels of the N18 cells can be activated by aconitine alone, indicating that they are voltage-dependent channels. In contrast, sodium channels in the C6 cells require the synergistic action of aconitine and scorpion toxin for activation and are therefore characterized as so-called silent channels. The general anesthetic halothane used at clinical concentrations, specifically inhibited the ion flux through the silent sodium channel of C6 rat glioma cells. The voltage-dependent channels of the N18 cells were insensitive to halothane at the concentrations tested.     

Fossil bananas (Musaceae): Ensete oregonense sp. nov. from the Eocene of western North America and its phytogeographic significance

Fossil seeds of Ensete, a genus presently native to Asia and Africa, have been recovered from the middle Eocene of Oregon, confirming the presence of Musaceae in the North American Tertiary. The seed of Ensete oregonense sp. nov. is operculate, with a well-defined micropylar collar, a pronounced chalazal chamber, and a wide hilar cavity. A survey of seed morphology in extant Zingiberales provides characters for distinguishing Musaceae from other families of the order, furnishes criteria for distinguishing the three extant genera of Musaceae (Musa, Ensete and Musella), and facilitates critical assessment of fossil seed remains. “Musa” cardiosperma Jain from the Cretaceous/Tertiary boundary Deccan Series of India is excluded from Musaceae (although retained in Zingiberales) on the basis of fruit and seed characters, including the lack of laticifers and absence of a chalazal chamber. We reexamined the musaceous seeds from Colombia that previously were described as Tertiary fossils (Musa enseteformis Berry, 1925) and now believe that they are recent, nonfossil remains, evidently from Ensete ventricosum, which is grown in the region where the specimens were originally obtained. In addition, a reputed fossil banana fruit from the Cretaceous of Colombia was reexamined and determined to be a concretion of nonbiological origin. Ensete oregonense is significant therefore, as the first unequivocal fossil record of Ensete and of Musaceae. Although the Musaceae are currently native only to the Old World tropics, this discovery establishes that the family was present in North America about 43 million years ago.     

Specific repression of a puff in the salivary gland chromosomes of Drosophila virilis after injection of glucosamine

Five hours after the injection of glucosamine into the hemolymph of Drosophila virilis larvae, puff 55E in the salivary gland chromosomes is significantly reduced in its activity. This observation in connection with the circumstances under which the activity of puff 55E decreases during normal development led to the proposition that its activity is involved in mucoprotein synthesis in the salivary glands during the third larval instar. Factors that may regulate the activity of puff 55E are discussed.