Brain metabolic activity associated with long-term memory consolidation

The use of day-old chickens trained on a single-trial passive avoidance task provides a useful paradigm for investigations into cellular mechanisms underlying memory formation. Pharmacological intervention studies indicate that there are three temporally identifiable stages of memory processing leading to the consolidation of information for this task. These stages, designated as short-term (STM; up to 15 min), intermediate-term (ITM; 15-55 min), and long-term (LTM; more than 55 min) memory, have been found to be sequentially dependent (Ng and Gibbs, 1989). In addition, ITM appears to consist of two physiologically distinguishable phases, A and B. Evidence in this laboratory suggests that the crossover between these ITM phases (at 30 min after training) represents a critical time-point for the triggering of LTM.     

Ras regulatory interactions: Novel targets for anti-cancer intervention?

Advances in the understanding of Ras oncoprotein function suggest novel points for anti-tumor intervention. First, upstream-acting guanine nucleotide exchange factors and SH2/SH3 domain-containing adaptor proteins that link Ras with growth factor receptor tyrosine kinases have recently been characterized. Second, work on downstream-acting Ras effector functions including the Ras GTPase-activating protein (p120^GAP) and the Raf kinase has revealed direct biochemical interactions that are functionally required for oncogenic Ras signalling. We summarize progress in these areas and discuss the potential for novel applications to anti-cancer chemotherapy.     

Epidermal keratin messenger RNAs: A heterogeneous family

A messenger RNA fraction from guinea-pig skin sediments on sucrose gradients at approx. 19 S and codes for keratin polypeptides in a messenger-dependent reticulocyte lysate system. Partial purification of this fraction was achieved by two cycles of chromatography on oligo(dT)-cellulose, followed by two cycles of sucrose gradient centrifugation. The identities of the protein products as keratins were established by co-electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, by peptide mapping, and by co-electrophoresis on two-dimensional polyacrylamide gels. All of the epidermal keratin polypeptides which are present in vivo are synthesized in vitro under the direction of this messenger. Fractionation of the messenger indicates that each different polypeptide is the product of a single mRNA species, and that no keratin is formed by proteolytic processing of higher molecular weight species or by polymerization of smaller precursors. Post-translational changes such as phosphorylation, which are known to occur in vivo, cannot be identified in the reticulocyte lysate system. Translation of these keratin messenger species is strongly inhibited by 7-methylguanosine 5′-triphosphate, indicating that the molecules have a ‘capped’ 5′-terminus.     

A study of the mating system in Dolichandra cynanchoides (Bignoniaceae): an Argentinian Chaco woodlands liane with a late-acting self-incompatibility

We estimated the outcrossing rate in a population of 14 individuals of Dolichandra cynanchoides (Bignoniaceae), a species with late-acting self-incompatibility (LSI), at a site in Chaco woodland in Santa Fe province, Argentina. A subsample of five arbitrarily chosen loci from a total of 16 allozyme loci gave mating system parameters of t_m=0.881 (SD 0.039) and t_s=0.749 (SD 0.048), thus indicating that although predominantly outcrossing, D. cynanchoides has a mixed mating system. We draw attention to the fact that mixed mating in species with LSI is a very likely scenario, given that previous studies with diverse LSI taxa have shown that mixed cross-self pollen loads on the stigma, which is probably a common occurrence with natural pollinators, result in fruits with a proportion of selfed seeds.     

Local or global? Biogeography of some primitive Lepidoptera in New Zealand

Abstract

Distribution maps are presented for 30 species of small forest moths representing two genera of Micropterigidae and one genus of Mnesarchaeidae. Evolutionary patterns are interpreted by means of the panbiogeographic method in order to seek a relationship between dispersal patterns within New Zealand and the overseas links of the taxa in question. It is established that different evolutionary lines indeed exhibit different geographic dispersal patterns within New Zealand. Moreover, certain characteristics of these patterns can be attributed to the overseas affinities of the groups, i.e., groups of organisms with New Caledonian or Australian affinities have a western disjunct pattern, whereas those with circum-Pacific affinities have a different pattern in which the taxa occupying a basal position in the phylogeny are to be found in the eastern South Island. However, both groups have overlapping centres of diversity, particularly in NW Nelson.     

A Molecular and Fitness Evaluation of Commercially Available versus Locally Collected Blue Lupine Lupinus perennis L. Seeds for Use in Ecosystem Restoration Efforts

Dependence on wild seed sources is often impractical for large‐scale habitat restoration programs. Reliance on commercial seed supplies of unknown provenance and fitness is thereby warranted. Little consideration has been given, however, to how the large volumes of seed required should be sourced. We evaluated commercial and locally collected seed sources for potential use in a New York State‐based, landscape‐scale program for restoring blue lupine Lupinus perennis. Through analysis of microsatellite markers we determined that “native” lupine designations by some commercial suppliers were in fact interspecific hybrids and therefore unreliable; at least two commercial sources, however, were genetically as close to native New York populations as native New York populations were to one other. Common garden experiments revealed that seed source influenced first‐year overwintering survival and subsequent height growth of surviving plants; seed sources more closely related genetically to native New York populations survived better and produced more stems per individual in the field in the area targeted for restoration. We conclude that (1) commercial suppliers often but not always offer reliably characterized seed sources of sufficient genetic similarity to native populations to warrant their use in restoration projects and (2) genetic affinity of potential seed stock to native populations is positively related to its fitness in the environment targeted for restoration.     

Characterization of Viral Load,Viability and Persistence of Influenza A Virus in Air and on Surfaces of Swine Production Facilities

Indirect transmission of influenza A virus (IAV) in swine is poorly understood and information is lacking on levels of environmental exposure encountered by swine and people during outbreaks of IAV in swine barns. We characterized viral load, viability and persistence of IAV in air and on surfaces during outbreaks in swine barns. IAV was detected in pigs, air and surfaces from five confirmed outbreaks with 48% (47/98) of oral fluid, 38% (32/84) of pen railing and 43% (35/82) of indoor air samples testing positive by IAV RT-PCR. IAV was isolated from air and oral fluids yielding a mixture of subtypes (H1N1, H1N2 and H3N2). Detection of IAV RNA from air was sustained during the outbreaks with maximum levels estimated between 7 and 11 days from reported onset. Our results indicate that during outbreaks of IAV in swine, aerosols and surfaces in barns contain significant levels of IAV potentially representing an exposure hazard to both swine and people.     

Differential post-translational modification of human type I keratins synthesized in a rabbit reticulocyte cell-free system

The translation products synthesized in a rabbit reticulocyte lysate system, from total cellular mRNA from the human epithelial cell-line ME-180, have been examined. Keratin proteins are prominent among these translation products, and they precisely coelectrophorese in sodium dodecyl sulfate-polyacrylamide gels with keratins purified from the cells. Type-I, acidic, keratins which are acetylated in vivo, are also acetylated by the reticulocyte lysate. Examination by two-dimensional electrophoresis, of two acidic keratins known to be phosphorylated in vivo reveals that only one of these proteins is phosphorylated in the lysate system. Phosphorylation of this protein occurs after release of the completed polypeptide chain from the ribosome. The protein phosphorylated by the lysate is known to be the only ME-180 phosphokeratin modulated by cyclic AMP, reflecting in vitro the differential modification of ME-180 keratins in vivo.