Effects of carbon dioxide concentration on the interactive effects of temperature and water vapour on stomatal conductance in soybean

Soybeans were grown at three CO₂ concentrations in outdoor growth chambers and at two concentrations in controlled-environment growth chambers to investigate the interactive effects of CO₂, temperature and leaf-to-air vapour pressure difference (LAVPD) on stomatal conductance. The decline in stomatal conductance with CO₂ was a function of both leaf temperature and LAVPD. In the field measurements, stomatal conductance was more sensitive to LAVPD at low CO₂ at 30 °C but not at 35 °C. There was also a direct increase in conductance with temperature, which was greater at the two elevated carbon dioxide concentrations. Environmental growth chamber results showed that the relative stomatal sensitivity to LAVPD decreased with both leaf temperature and CO₂. Measurements in the environmental growth chamber were also performed at the opposing CO₂, and these experiments indicate that the stomatal sensitivity to LAVPD was determined more by growth CO₂ than by measurement CO₂. Two models that describe stomatal responses to LAVPD were compared with the outdoor data to evaluate whether these models described adequately the interactive effects of CO₂, LAVPD and temperature.     

Egg parasitoids (Hymenoptera: Mymaridae) of Amrasca biguttula (Ishida) (Hemiptera: Cicadellidae) on Okinawa Island,a pest of okra in Japan

The fairyfly Anagrus (Anagrus) japonicus Sahad (Hymenoptera: Mymaridae) is identified for the first time as an egg parasitoid of the okra leafhopper Amrasca (Sundapteryx) biguttula (Ishida) (Hemiptera: Cicadellidae) on Okinawa Island, Japan. Amrasca biguttula is a serious pest of okra, Abelmoschus esculentus (L.) Moench (Malvaceae), both in Okinawa and Bonin Islands. Female of A. japonicus is redescribed, and its previously unknown male is described, based on the reared specimens from Okinawa. Prior to this study, host associations of A. japonicus were unknown. Another species of Mymaridae, Arescon enocki (Subba Rao and Kaur), also emerged from eggs of A. biguttula on okra in Okinawa, albeit in much smaller numbers.     

An expanded comparative map of bovine chromosome 27 targeting dairy form QTL regions

At present, the density of genes on the bovine maps is extremely limited and current resolution of the human-bovine comparative map is insufficient for selection of candidate genes controlling many economic traits of interest in dairy cattle. This study describes the chromosomal mapping of 10 selected gene-associated markers to bovine linkage and radiation hybrid maps to improve the breakpoint resolution in the human-bovine comparative map near two previously identified quantitative trait loci for the linear type trait, dairy form. Two regions of conserved synteny not previously described are reported between the telomeric region of bovine chromosome 27 (BTA27) and human chromosome 3 (HSA3) p24 region and between the HSA4q34.1 region and BTA8. These data increase the number of genes positioned on the bovine gene maps, refine the human-bovine comparative map, and should improve the efficiency of candidate gene selection for the dairy form trait in cattle.     

"Emerging" parasitic infections in arctic ungulates

Important drivers for emergence of infectious disease in wildlifeinclude changes in the environment, shrinking habitats or concentrationof wildlife, and movement of people, animals, pathogens, orvectors. In this paper we present three case-studies of emergingparasitic infections and diseases in ungulates in the Canadiannorth. First we discuss climate warming as an important driverfor the emergence of disease associated with Umingmakstrongyluspallikuukensis, a nematode lungworm of muskoxen. Then we examinehow Protostrongylus stilesi, the sheep lungworm, emerged (orre-emerged) in muskoxen after re-introduction of this host intoits historical range made it sympatric with Dall's sheep. Finally,we consider Teladorsagia boreoarcticus, a newly described andcommon abomasal nematode of muskoxen that is emerging as a disease-causingparasite and may be an important regulator for muskox populationson Banks Island, Northwest Territories. These and other arctichost-parasite systems are exquisitely tuned and constrainedby a harsh and highly seasonal environment. The dynamics ofthese systems will be impacted by climate change and other ecologicaldisruptions. Baseline knowledge of parasite biodiversity andparasite and host ecology, together with predictive models andlong-term monitoring programs, are essential for anticipatingand detecting altered patterns of host range, geographic distribution,and the emergence of parasitic infections and diseases.     

Predicted ATP-binding cassette systems in the phytopathogenic mollicute <Emphasis Type="Italic">Spiroplasma kunkelii</Emphasis>

Spiroplasma kunkelii is a cell wall-free, helical, and motile mycoplasma-like organism that causes corn stunt disease in maize. The bacterium has a compact genome with a gene set approaching the minimal complement necessary for cellular life and pathogenesis. A set of 21 ATP-binding cassette (ABC) domains was identified during the annotation of a draft S. kunkelii genome sequence. These 21 ABC domains are present in 18 predicted proteins, and are components of 16 functional systems, which account for 5% of the protein coding capacity of the S. kunkelii genome. Of the 16 systems, 11 are membrane-bound transporters, and two are cytosolic systems involved in DNA repair and the oxidative stress response; the genes for the remaining three hypothetical systems harbor nonsense and/or frameshift mutations, so their functional status is doubtful. Assembly of the 11 multicomponent transporters, and comparisons with other known systems permitted functional predictions for the S. kunkelii ABC transporter systems. These transporters convey a wide variety of substrates, and are critical for nutrient uptake, multidrug resistance, and perhaps virulence. Our findings provide a framework for functional characterization of the ABC systems in S. kunkelii.Communicated by W. Goebel     

<Emphasis Type="Italic">Hypocrea phyllostachydis</Emphasis> and its <Emphasis Type="Italic">Trichoderma</Emphasis> anamorph,a new bambusicolous species from France

Hypocrea phyllostachydis was collected from the bamboo species Phyllostachys bambusoides in southwestern France (Dept. Pyréneés Atlantiques). It can be distinguished from other morphologically similar species by the small subglobose or broadly ellipsoidal conidia and small ascospores. Conidiophores of the Trichoderma state of H. phyllostachydis do not branch in a pyramidal fashion, as is typical of most species of Trichoderma. Rather, it has an irregular branching pattern, with a long central axis and relatively short lateral secondary branches. A key to species of Hypocrea with green ascospores from France is presented.     

Polyphyly and two emerging lineages in the rust genera Puccinia and Uromyces

The phylogenetic validity of Puccinia and Uromyces, Pucciniaceae, and closely related genera was evaluated using nucLSU rDNA sequences. Using a wide range of rust species with different life cycles and with different host specificities, Puccinia and Uromyces were shown to be highly polyphyletic and to also include representatives of the genera Aecidium, Cumminsiella, Dietelia, Endophyllum, Miyagia, and Uredo. Furthermore, the structure of the phylogenetic data did not reflect previous sub-generic delimitations based on teliospore pedicel structure, but rather suggests that at least two major lineages have evolved within Puccinia/Uromyces: Rusts with telial states on Poaceae were exclusively found in one of these groupings and those with telial states on Cyperaceae resided in the other lineage. This might suggest that the two lineages evolved in close association with these host groups in different biomes.     

A new species of mammalian trypanosome,Trypanosoma (Megatrypanum) bubalisi sp. nov., found in the freshwater leech Hirudinaria manillensis

Leeches have long been considered potential vectors for the aquatic lineage of trypanosomes, while bloodsucking insects are generally considered as the vectors for the terrestrial lineage of trypanosomes. The freshwater leech, Hirudinaria manillensis, is a widely distributed species in southern China and could potentially act as the vector for trypanosomes. Prior to this study, no trypanosomes had been reported from this leech. However, in this study, leeches were collected from three different places in Guangdong province, China, and a large number of flagellates were isolated and successfully cultured in vitro. Based on morphology, these flagellates looked like a typical trypanosome species. Analysis was carried out on the molecular sequences of the 18S rRNA gene and the glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene. To our surprise, these flagellates were identified as likely to be a mammalian trypanosome belonging to the clade containing Trypanosoma (Megatrypanum) theileri but they are significantly different from the typical TthI and TthII stocks. Analyses of blood composition indicated that the source of the blood meal in these leeches was from the water buffalo (Bubalus bubalis). To further test if this flagellate from the freshwater leech was indeed a mammalian trypanosome, we transferred the trypanosomes cultured at 27–37 °C and they were able to successfully adapt to this mammalian body temperature, providing further supporting evidence. Due to the significant genetic differences from other related trypanosomes in the subgenus Megatrypanum, we propose that this flagellate, isolated from H. manillensis, is a new species and have named it Trypanosoma bubalisi. Our results indicate that freshwater leeches may be a potential vector of this new mammalian trypanosome.