The prevalence of avian haemosporidian parasites in an invasive bird is lower in urban than in non-urban environments

Urbanization affects the ecology of wildlife diseases and although it has been suggested that there are lower risks of infection in urban areas, there have been no experiments to support this conclusion. We assessed haemosporidian prevalence and intensity in House Sparrows Passer domesticus using field and experimental data under contrasting conditions (i.e. urban vs. non-urban). For experimental data, we kept 32 male House Sparrows in captivity as a proxy of stress, and for field data we sampled 49 House Sparrows (17 females). We made use of microscopy to determine the relative intensity and used the polymerase chain reaction to estimate infection prevalence. We obtained total leucocyte counts, leucocyte differentials, heterophil/lymphocyte ratio (H/L) as a measure of stress, and the Polychromatic Index as a measure of physiological condition (erythropoiesis). We identified a total of 10 haemosporidian lineages. For field samples (both males and females), we found a significantly higher prevalence of infection in non-urban House Sparrows than in urban ones. Under experimental conditions, non-urban House Sparrows showed a higher prevalence than urban ones both before and after captivity, with a significant increase in parasite intensity. The number of infected birds increased after captivity for both urban (~ 32%) and non-urban House Sparrows (~ 19%), indicating either a recrudescence of chronic and relapses of latent infections or the appearance of infections that had been acquired earlier. The H/L ratio was significantly higher for non-urban than for urban male House Sparrows before captivity. No difference in H/L was found for urban House Sparrows before and after captivity, indicating tolerance to city stressors. Our results showed a significant decrease in H/L for non-urban birds after captivity, suggesting higher stress in the non-urban agricultural environment. Haemosporidian infections were not associated with the H/L ratio. Our study provides evidence that highly urbanized areas within cities represent lower haemosporidian infection risks than do non-urban areas for House Sparrows.     

The phylogeny and taxonomy of austral monodontine topshells (Mollusca: Gastropoda: Trochidae), inferred from DNA sequences

The systematics of topshells (family Trochidae) is currently unresolved: at present even the generic boundaries within this group are poorly defined. In this study, we used sequence data of two mitochondrial genes (16S and cytochrome oxidase 1, COI) and one nuclear gene (actin) to resolve the phylogeny of a closely related subgroup of the Trochidae, 30 species of largely Southern Hemisphere monodontine topshells. The phylogenies constructed revealed five well-supported generic clades: a South African clade (genus Oxystele Philippi, 1847), which lay basally to four internal Pacific clades (genera Chlorodiloma Pilsbry, 1889; Monodonta Lamarck, 1799; Austrocochlea Fischer, 1885; and Diloma Philippi, 1845). The molecular phylogenies constructed in this study shed light on previously unresolved relationships between different groups of topshells, allowing for the first time assignation (based on DNA sequence) of clearly defined, well-supported taxonomic and nomenclatural classification of monodontine topshells species. Austrocochlea crinita (Philippi, 1849), A. odontis (Wood, 1828), A. adelaidae (Philippi, 1849), and A. millelineata (Bonnet, 1864) are placed in the genus Chlorodiloma, which we resurrect from synonymy with Austrocochlea. The Japanese M. confusa Tapparone-Canefri, 1874 is treated as a separate species from M. labio (Linné, 1758). Melagraphia Gray, 1847 is synonymised with Diloma and its sole member, M. aethiops (Gmelin, 1791), along with A. concamerata (Wood, 1828), is transferred to that genus. The Juan Fernandez endemic D. crusoeana (Pilsbry, 1889) is synonymised with D. nigerrima (Gmelin, 1791). We find that morphologically cryptic species are not necessarily close genetically.     

Ultrafast evolution and loss of CRISPRs following a host shift in a novel wildlife pathogen, Mycoplasma gallisepticum

Measureable rates of genome evolution are well documented in human pathogens but are less well understood in bacterial pathogens in the wild, particularly during and after host switches. Mycoplasma gallisepticum (MG) is a pathogenic bacterium that has evolved predominantly in poultry and recently jumped to wild house finches (Carpodacus mexicanus), a common North American songbird. For the first time we characterize the genome and measure rates of genome evolution in House Finch isolates of MG, as well as in poultry outgroups. Using whole-genome sequences of 12 House Finch isolates across a 13-year serial sample and an additional four newly sequenced poultry strains, we estimate a nucleotide diversity in House Finch isolates of only ～2% of ancestral poultry strains and a nucleotide substitution rate of 0.8-1.2×10(-5) per site per year both in poultry and in House Finches, an exceptionally fast rate rivaling some of the highest estimates reported thus far for bacteria. We also found high diversity and complete turnover of CRISPR arrays in poultry MG strains prior to the switch to the House Finch host, but after the invasion of House Finches there is progressive loss of CRISPR repeat diversity, and recruitment of novel CRISPR repeats ceases. Recent (2007) House Finch MG strains retain only ～50% of the CRISPR repertoire founding (1994-95) strains and have lost the CRISPR-associated genes required for CRISPR function. Our results suggest that genome evolution in bacterial pathogens of wild birds can be extremely rapid and in this case is accompanied by apparent functional loss of CRISPRs.     

褪黑素通过减弱催乳素基因增强子的突变抑制大鼠垂体催乳素瘤的增生

本工作旨在探讨褪黑素(melatonin,MLT)抑制17-β-雌二醇(17-β-estradiol,E2)诱发的Sprague-Dawley大鼠垂体催乳素(prolactin,PRL)瘤增生的分子机制。结果表明,每只大鼠每日定时皮下注射一定剂量的MLT(0.25、0.50mg)能显著抑制E2诱发的大鼠垂体PRL瘤的增生;偏低(0.05mg)或过高剂量(1.00、2.00mg)的MLT也抑制PRL瘤的增生,但无统计学意义。采用PCR和DNA直接测序显示,与正常垂体对照组比较,PRL瘤中PRL基因增强子出现五处突变,-1885bp位点由C突变为G,-1857~-1855由ACA替换为G,-1792~-1791插入G,-1383~-1382插入GGTGTGTG片段,-1265~-1250缺失GTGTGTGTGTGTGTGT片段。0.25mg/dMLT处理组,PRL瘤中的PRL基因增强子上述个别突变部位仍然存在(-1885由C突变为G),突变消失(-1792~-1791无插入G),大部分表现为突变减弱(-1856~-1855缺失AC,-1385~-1384缺失TG,-1250~-1253缺失GTGT)。采用荧光素酶报告基因检测PRL基因增强子活性显示,正常垂体、PRL瘤和0.25mg/dMLT处理的PRL瘤三组中,PRL基因增强子的活性分别为(13448.17±3012.74)、(161831.67±60996.01)和(10212.17±2634.71)OD单位。PRL瘤组增强子活性较正常垂体升高11倍(P<0.001),MLT处理组增强子活性较PRL瘤组降低93.69%(P<0.001)。上述三组PRL基因增强子空间结构的分析表明,PRL基因增强子DNA的曲折程度为PRL瘤组>MLT处理组>正常垂体。以上结果证实,MLT抑制大鼠垂体PRL瘤增生的重要分子机制之一可能是减弱PRL基因增强子的突变,也提示MLT可减弱PRL基因增强子的突变,从而下调PRL基因的高表达,可能与降低DNA的曲折程度有关。     

Electrode Fabrication and Implantation in Aplysia californica for Multi-channel Neural and Muscular Recordings in Intact,Freely Behaving Animals

Recording from key nerves and muscles of Aplysia during feeding behavior allows us to study the patterns of neural control in an intact animal. Simultaneously recording from multiple nerves and muscles gives us precise information about the timing of neural activity. Previous recording methods have worked for two electrodes, but the study of additional nerves or muscles required combining and averaging the recordings of multiple animals, which made it difficult to determine fine details of timing and phasing, because of variability from response to response, and from animal to animal. Implanting four individual electrodes has a very low success rate due to the formation of adhesions that prevent animals from performing normal feeding movements. We developed a new method of electrode fabrication that reduces the bulk of the electrodes inside the animal allowing for normal feeding movements. Using a combination of glues to attach the electrodes results in a more reliable insulation of the electrode which lasts longer, making it possible to record for periods as long as a week. The fabrication technique that we describe could be extended to incorporate several additional electrodes, and would be applicable to vertebrate animals.Download video file.^{(145M, mp4)}     

Expression of the Synechocystis sp. strain PCC 6803 tRNA(Glu) gene provides tRNA for protein and chlorophyll biosynthesis.

In the cyanobacterium Synechocystis sp. strain PCC 6803 (Synechocystis 6803) delta-aminolevulinic acid (ALA), the sole precursor for the synthesis of the porphyrin rings of heme and chlorophyll, is formed from glutamate activated by acylation to tRNA(Glu) (G. P. O'Neill, D. M. Peterson, A. Sch?n, M. W. Chen, and D. S?ll, J. Bacteriol. 170:3810-3816, 1988; S. Rieble and S. I. Beale, J. Biol. Chem. 263:8864-8871, 1988). We report here that Synechocystis 6803 possesses a single tRNA(Glu) gene which was transcribed as monomeric precursor tRNA and matured into the two tRNA(Glu) species. They differed in the extent of modification of the first anticodon base, 5-methylaminomethyl-2-thiouridine (O'Neill et al., 1988). The two tRNA species had equivalent capacities to stimulate the tRNA-dependent formation of ALA in Synechocystis 6803 and to provide glutamate for protein biosynthesis in an Escherichia coli-derived translation system. These results are in support of a dual role of tRNA(Glu). The levels of tRNA(Glu) were examined by Northern (RNA) blot analysis of cellular RNA and by aminoacylation assays in cultures of Synechocystis 6803 in which the amount of chlorophyll synthesized was modulated over a 10-fold range by various illumination regimens or by the addition of inhibitors of chlorophyll and ALA biosynthesis. In these cultures, the level of tRNA(Glu) was always a constant fraction of the total tRNA population, suggesting that tRNA(Glu) and chlorophyll levels are regulated independently. In addition, the tRNA(Glu) was always fully aminoacylated in vivo.     

Structure and synthesis of a lipid-containing bacteriophage. The molecular weight and other physical properties of bacterophage PM2.

Several physical and chemical parameters of bacteriophage PM2 have been measured. The sedimentation constant was determined to be s-20,w=293 S. The buoyant density in sucrose at 20 degrees C was 1.24 g cm+-3 and in CsCl at 25 degrees C was 1.29 g cm-3. The high-speed equilibrium centrifugation method of Yphantis (1964) was used to measure the molecular weight of PM2. The necessary auxiliary parameters were also determined. A value of 0.771 plus or minus 0.005 cm-3 g-1 for the apparent specific volume at constant chemical potential in 1 M sodiium chloride has been obtained by pycnometry; the viral concentration was determined using the absorption coefficient at 260 nm (4.60 plus or minus 0.10 cm-2 mg-1), which in turn was calculated from the phosphorous content of the virus (17.89 plus or minus 0.28 mu-g of P per mg dry weight dry weight of virus). The molecular weight of PM2 determined with these parameters is (44.1 plus or minus 1.2 x 10-6). From the phosphorous content of the virus, the percentage of phosphorous known to be in its DNA (Camerini-Otero and Franklin, 1972), and the molecular weight of the bacteriophage, we have calculated a molecular weight for PM2 DNA of 6.26 x 10-6, which confirms values determined using empirical relationships.     

Micropropagation of Phalaenopsis and Doritaenopsis by culturing shoot tips of flower stalk buds

Green Protocorm-like Bodies (PLB) with high multiplication capacity were induced from shoot tips of flower stalk buds having 1 or 2 leaf primordia using New Dogashima Medium (NDM) containing 0.1 mg l^–1 -naphthaleneacetic acid (NAA) and 1 mg 1^–1 6-benzylaminopurine (BAP). These PLB were subcultured on the same medium. More than 10,000 PLBs were obtained from a few buds on a single flower stalk within one year. After transfer onto NDM containing no plant growth regulator (PGR), the PLB developed into plantlets. The micropropagation method formulated in this study was applicable to 12 different genotypes. These results suggest that the methodology could be used on a commercial scale for vegetative propagation of Phalaenopsis and Doritaenopsis.Abbreviations PLB protocorm-like body - PGR plant growth regulator - NAA -naphthaleneacetic acid - BAP 6-benzylaminopurine - NDM New Dogashima Medium     

Species composition and structure of Thysanoptera communities in different microhabitats at the Parque Estadual de Itapu?, Viam?o, RS.

Although thrips are known as inhabitants of flowers, they are also abundant and diverse in other microhabitats. There is an information gap concerning them, especially related to the native fauna in southern Brazil. The structure and composition of the thysanopteran community in different microhabitats was studied at the "Parque Estadual de Itapu?" (30 degrees 22' S 51 degrees 02' W), RS, southern Brazil. Between June 1999 and May 2001, branches (n = 1,274), flowers (n = 774), grass tussocks (n = 596) and leaf litter (n = 603) were sampled systematically in 20 points of four trails (T1 - Pedreira beach, T2 - Ara?á beach, T3 - Lagoinha, and T4 - Grota hill). We found 2,197 adult thrips determined in 73 species in 41 genera, of which 37 could be nominated. Four families are represented, Thripidae, Phlaeothripidae, Heterothripidae and Merothripidae, with the first the most abundant (N = 1,599) and with the highest species richness (S = 32). The highest thrips abundance occurred in flowers N = 1,224 and the highest number of exclusive species occurred in the leaf litter (27). Frankliniella rodeos Moulton, 1933, Frankliniella gemina Bagnall, 1919 and Smicrothrips particula Hood, 1952 comprise 49.4% of the total sampled. Regarding T2, we obtained the highest abundance (N = 935) and highest species richness (S = 43). The composition of the faunas in each kind of environment proved very particular.     

Essay review

Crocodilian Biology and Evolution, edited by Gordon C. Grigg, Frank Seebacher, and Craig E. Franklin, 2001. Surrey Beatty and Sons (43 Rickard Road, Chipping Norton 2170 NSW, Australia), x+446p. ISBN 0-949-324 89-2 (hardback), Aust$99     

Evidence that Kenyan House Sparrows Passer domesticus invaded from multiple sites

Here we characterize genetic patterns across the range of House Sparrows in Kenya using six microsatellite markers. We screened House Sparrows from two remote locations in northern Kenya, Marsabit (n = 24) and Wajir (n = 27), which are separated from other colonized areas in Kenya by minimally developed, arid habitat, and then compared these birds with House Sparrows in 10 more central and longer established Kenyan cities (n = 233) in this range. House Sparrows from Marsabit and Wajir originated from a separate source, probably Somalia and/or Ethiopia, from other Kenyan House Sparrows, probably Mombasa. Furthermore, the genetic characteristics of northern and southern populations indicate that they have not yet mixed, supporting a hypothesis that the large, minimally (human) developed, arid landscape spanning nearly all of northern Kenya, including the 100 000 km² Chalbi Desert, is a barrier to dispersal for House Sparrows.     

Comparison of two yeast invertase genes: conservation of the upstream regulatory region.

The yeast genome contains a dispersed family of invertase structural genes (SUC1-SUC5, SUC7). Five of these genes are located very close to telomeres and are flanked by large regions of homologous sequence; recombination between telomeres could account for the dispersal of these SUC genes to different chromosomes. The SUC2 locus, in contrast, is not near a telomere and does not share large regions of flanking homology with the other loci. We examine here the relationship between SUC2 and one of the telomeric genes, SUC7. Sequence comparison revealed homology extending from about position -624 to +1791, which is close to the end of the mRNA. The 5' noncoding sequence includes two highly conserved regions: the region between -140 and +1, which contains the TATA box and presumably other promoter elements, and a second region extending from -508 to -400, which corresponds to the upstream regulatory region.     

Energetics of free existence in swallows and martins (hirundinidae) during breeding: a comparative study using doubly labeled water

Energy metabolism of three sympatric swallows (Hirundinidae) was investigated during the breeding season using doubly labeled water (²H₂ ¹⁸O). Interspecific and intraspecific differences in energy metabolism were examined in relation to the habits, size and environment of the birds. To facilitate comparisons we expressed energy metabolism (M) as the ratio of average daily metabolic rate (ADMR, cm³CO_2g ^-1h^-1) to basal metabolic rate (BMR). We observed adults during incubation and when feeding nestlings. Then, both sexes of Sand Martins Riparia riparia and House Martins Delinchon urbica were either at the nest or on the wing. Incubation reduced activity levels during the day resulting in M (incubation) being 17–26% lower than during rearing. Differences in energy costs for rearing chicks depended mainly on flight behaviour, the smaller Sand Martin doing nearly twice as much flapping during flight as the House Martin, giving higher values for M. In Swallows Hirundo rustica the female incubates alone, alternating between short feeding trips and incubating in daytime. This pattern was linked with a relatively high value for M in the only individual behaving like our controls. Both sexes of Swallows feed the chicks, and they showed similar values of M. They also closely resembled House Martins, despite contrasts in the time spent flying and their behaviour during flight. Feeding conditions affected activity, and thereby M, in a species specific way. The House Martin did more gliding in poor weather, taking less mobile prey, reducing M. Swallows reduced foraging costs further by using body reserves, as in the House Martin. The smaller Sand Martin, in contrast, showed a high expenditure in poor weather. Over two breeding seasons ADMR reached values around 5 BMR for all three species.     

Stone-tool usage by Thai long-tailed macaques (Macaca fascicularis)

In January and March of 2005, we conducted surveys of long-tailed macaques at Piak Nam Yai Island, Laem Son National Park (9 degrees N 34-35', 98 degrees E 28'), Ranong Province, situated in southern Thailand. Two of the three troops of long-tailed macaques found on the island were observed using axe-shaped stones to crack rock oysters, detached gastropods (Thais tissoti, Petit, 1852), bivalves (Gafrarium divaricatum, Gmelin, 1791), and swimming crabs (Thalamita danae, Stimpson, 1858). They smashed the shells with stones that were held in either the left or right hand, while using the opposite hand to gather the oyster meat. Some monkeys used both hands to handle the stones. According to Matsuzawa's 1996 hierarchical classification of tool usage (levels 0-3), the tool usage by Thai long-tailed macaques could be characterized as either level 1 (cracking rock oysters with stones) or level 2 (cracking drifting mollusks and crabs with stones by placing them on a rock). Our discovery of stone-tool usage by Thai long-tailed macaques provides a new point of reference for discussions regarding the evolution of tool usage and the material culture of primates.     

Highly variable effects of beryllium and beryllium fluoride on tubulin polymerization under different reaction conditions: comparison of assembly reactions dependent on microtubule-associated proteins, glycerol, dimethyl sulfoxide, and glutamate.

Carlier et al. (1988, Biochemistry 27, 3555-3559; 1989, Biochemistry 28, 1783-1791) described enhancement of tubulin polymerization and stabilization of glycerol-induced microtubules by BeF3- (by addition of both BeSO4 and NaF to reaction mixtures). We were able to confirm the stabilization of glycerol-induced polymer reported by these workers, provided Mg2+ was also present in the reaction. When we examined polymerization dependent on microtubule-associated proteins (MAPs), however, we obtained very different results. BeF3- had no significant effect on this reaction, or the polymer formed, under any condition examined. Lower concentrations of BeSO4 alone, in contrast to a negligible effect in glycerol, enhanced polymerization with MAPs provided the concentrations of both Mg2+ and GTP were low; and Be2+ stabilized the polymer, if the GTP concentration was low, at both low and high Mg2+ concentrations. Higher concentrations of BeSO4 precipitated tubulin, an effect which was not affected by Mg2+, partially prevented but not reversed by MAPs, and prevented or reversed by either NaF or nucleotides at adequate concentrations. These results suggest that Be2+ binds at site(s) distinct from Mg2+ site(s), and that partial occupancy of these site(s) at lower Be2+ concentrations enhances tubulin polymerization and polymer stability, while extensive occupancy at higher Be2+ concentrations results in tubulin precipitation. Effects of Be2+ and BeF3- on polymerization dependent on dimethyl sulfoxide or glutamate were also evaluated. The dimethyl sulfoxide system displayed properties similar to those of the glycerol system, while the glutamate system was similar to the MAPs system.     

Weed Dynamics during Transition to Conservation Agriculture in Western Kenya Maize Production

Weed competition is a significant problem in maize (Zea mays, L.) production in Sub-Saharan Africa. Better understanding of weed management and costs in maize intercropped with beans (Phaseolus vulgaris, L.) during transition to conservation agricultural systems is needed. Changes in weed population and maize growth were assessed for a period of three years at Bungoma where crops are grown twice per year and at Trans-Nzoia where crops are grown once per year. Treatments included three tillage practices: minimum (MT), no-till (NT) and conventional (CT) applied to three cropping systems: continuous maize/bean intercropping (TYPICAL), maize/bean intercropping with relayed mucuna after bean harvest (RELAY) and maize, bean and mucuna planted in a strip intercropping arrangement (STRIP). Herbicides were used in NT, shallow hand hoeing and herbicides were used in MT and deep hoeing with no herbicides were used in CT. Weed and maize performance in the maize phase of each cropping system were assessed at both locations and costs of weed control were estimated at Manor House only. Weed density of grass and forb species declined significantly under MT and NT at Manor House and of grass species only at Mabanga. The greatest declines of more than 50% were observed as early as within one year of the transition to MT and NT in STRIP and TYPICAL cropping systems at Manor House. Transitioning to conservation based systems resulted in a decline of four out of five most dominant weed species. At the same time, no negative impact of MT or NT on maize growth was observed. Corresponding costs of weed management were reduced by $148.40 ha^-1 in MT and $149.60 ha^-1 in NT compared with CT. In conclusion, farmers can benefit from effective and less expensive weed management alternatives early in the process of transitioning to reduced tillage operations.     

A nonlethal mutation in large T antigen of polyomavirus which affects viral DNA synthesis.

A mutation in polyomavirus large T antigen which affects viral DNA synthesis was discovered in strain NG59RA (RA). The effect was most visible in nonpermissive cells. Although a substantial yield in DNA synthesis is normally observed in infections of Fischer rat cells when these are maintained at 33 degrees C (D.L. Hacker, K.H. Friderici, C. Priehs, S. Kalvonjian, and M.M. Fluck, p. 173-181, in R.E. Moses and W.C. Summers, ed., DNA Replication and Mutagenesis, 1988; D.L. Hacker and M.M. Fluck, Mol. Cell. Biol., in press), a 10- to 20-fold decrease in yield was obtained in infections with RA. The yield of free viral DNA in RA transformants was also strongly diminished, whether the transformants were maintained at 37 or 33 degrees C. A large reduction in the apparent number of integration sites, as well as a small reduction in the incidence of tandem integration of the viral genome, was observed in F-111 or FR-3T3 cells transformed by the mutant strain. This appears not to be directly related to the number of integration templates. A DNA fragment was identified which rescues these phenotypes. The fragment is located between the HindIII and NsiI restriction sites (nucleotides 1656 to 1910), a region which encodes only large T antigen. Sequence analysis of this region reveals a C-to-G transition at nucleotide 1791 which causes a proline-to-alanine change in the amino acid sequence of large T antigen. No other mutations have been previously reported in this region of large T antigen.     

PENN neurodegenerative disease research - in the spirit of Benjamin Franklin

Benjamin Franklin (1706-1790) was entrepreneur, statesman, supporter of the public good as well as inventor, and his most significant invention was the University of Pennsylvania (PENN). Franklin outlined his plans for a college providing practical and classical instruction to prepare youth for real-world pursuits in his 'Proposals Relating to the Education of Youth in Pensilvania' (1749), and Franklin's spirit of learning to serve society guides PENN to the present day. This is evidenced by the series of articles in this special issue of Neurosignals, describing research conducted by seasoned and newly recruited PENN faculty, addressing consequences of the longevity revolution which defines our epoch at the dawn of this millennium. While aging affects all organ systems, the nervous system is most critical to successful aging. Thus, the articles in this special issue of Neurosignals focus on research at PENN that is designed to prevent or ameliorate aging-related neurodegenerative disorders such as Alzheimer's and Parkinson's disease, amyotrophic lateral sclerosis and frontotemporal dementia. This research could enhance our chances of aging successfully in the continuing longevity revolution, and the essay here provides context and background on this research.