Impacts of plant roots on soil CO cycling and soil–atmosphere CO exchange

Carbon monoxide (CO) plays a major role in tropospheric chemical dynamics. Accordingly, global CO budgets have been reasonably well documented. Atmospheric CO consumption by soils contributes significantly to these budgets, with the magnitude of the sink generally considered to reflect a balance between microbial uptake and abiological production. However, assays of live fine roots showed that diverse intact plants produced carbon monoxide at net rates ranging from 2 to 3000 mµg gdw⁻⁻¹ d⁻⁻¹. CO production was greater for legumes than nonlegumes, and primarily associated with nodules. Excised roots from woody and herbaceous plants produced CO at comparable rates. CO production rates were similar for roots of intact plants and roots excised from those plants. The magnitude of net CO fluxes from roots was determined in part by the balance between simultaneous production and consumption. Surface sterilization of roots indicated that CO consumption was due, in part, rhizoplane CO-oxidizing bacteria, but maximum CO consumption rates were typically only a small fraction of net production rates. Assays in a Brazilian agroecosystem indicated that root CO production affects soil–atmosphere CO exchange. Estimates of global CO production rates indicated that roots contribute about 170–260 Tg CO to the soil atmosphere annually, an amount comparable to current estimates of atmospheric CO uptake by soils, and much larger than estimates of net abiological soil CO production.     

Development of Eimeria ninakohlyakimovae from Sheep In Cell Cultures*

SYNOPSIS. Monolayer cell line cultures of ovine trachea, thyroid, thymus, and kidney cells, as well as an established cell line (Madin-Darby) of bovine kidney cells, were inoculated with sporozoites of Eimeria ninakohlyakimovae and observed for a maximum of 24 days. Sporozoites were seen penetrating cells within 5 minutes after inoculation, as well as 2 and 3 days after inoculation, and leaving cells 3 days after inoculation. Transformation from sporozoites to trophozoites occurred by a widening or by a lateral outpocketing of the sporozoite body. Trophozoites and schizonts were first seen 3 days after inoculation in all ovine cell types. Large numbers of immature schizonts were observed, but only an estimated 0.4–4.3% of these became mature in the different kinds of cells. Usually, mature schizonts were first seen 10–11 days after inoculation in the ovine cells, but they sometimes occurred as early as 8 days. More mature schizonts were seen in the ovine kidney and trachea cells than in the others; the smallest number occurred in the bovine cells. The nucleoli of cells harboring large schizonts in each type of culture were enlarged and the chromatin clumps normally seen in the nuclei of non-infected cells were not visible. The cytoplasm of some infected cells was vacuolated. The formation of merozoites occurred by a budding process from blastophores, from the surface of schizonts, and/or from infoldings and invaginations of this surface. Merozoites were observed leaving host cells, but were not seen penetrating new cells. Intracellular first-generation merozoites were observed 13 and 15 days after inoculation in lamb trachea and kidney cells, respectively. No evidence of further development of such merozoites was found.     

The Mouse Pink-Eyed Dilution Gene: Association with Hypopigmentation in Prader-Willi and Angelman Syndromes and with Human OCA2

Mutations at the mouse pink-eyed dilution locus, p, cause hypopigmentation. We have cloned the mouse p gene cDNA and the cDNA of its human counterpart, P. The region of mouse chromosome 7 containing the p locus is syntenic with human chromosome 15q11-q13, a region associated with Prader-Willi syndrome (PWS) and Angelman syndrome (AS), both of which involve profound imprinting effects. PWS patients lack sequences of paternal origin from 15q, whereas AS patients lack a maternal copy of an essential region from 15q. However, the critical regions for these syndromes are much smaller than the chromosomal region commonly deleted that often includes the P gene. Hypopigmentation in PWS and AS patients is correlated with deletions of one copy of the human P gene that is highly homologous with its mouse counterpart. A subset of PWS and AS patients also have OCA2. These patients lack one copy of the P gene in the context of a PWS or AS deletion, with a mutation in the remaining chromosomal homologue of the P gene. Mutations in both homologues of the P gene of OCA2 patients who do not have PWS or AS have also been detected.     

OLFACTORY DECREMENTS AS A FUNCTION OF TWO NIGHTS OF SLEEP DEPRIVATION

We recently reported that odor identification accuracy declined significantly following 24 h of continuous wakefulness. In the present study, we attempted to extend these findings by testing odor identification accuracy when the duration of wakefulness was more than doubled to over 52 h. The accuracy of odor identification decreased significantly following this period of extended wakefulness, although performance decrements were similar in magnitude to those previously reported following 24 h without sleep. These findings suggest that sleep loss impairs the ability to correctly identify common odors, but this effect does not appear to be exacerbated by additional sleep loss beyond the first 24 h.     

Fish assemblage patterns in the littoral zone of a European reservoir

1. Although reservoirs are common aquatic habitats in Europe, there is little quantitative information on the spatial organisation of fish assemblages inhabiting their littoral zones. Consequently, we characterised fish assemblage structure in the littoral zone of a reservoir (Lake Pareloup) in SW France during late spring, summer and early autumn (the growing season).
2. We measured the relative abundance of fish weekly, from mid-May to mid-October, using point abundance sampling by electrofishing. We identified temporal patterns in assemblage structure using hierarchical cluster analysis, and then characterised the spatial distribution of 17 defined ecospecies using a Kohonen self-organising map (SOM, an unsupervised Artificial Neural Network).
3. Our analyses revealed three distinct faunal structures within the littoral zone. From mid-May to mid-July, adults and young-of-the-year (0+) occupied separate habitats, with most 0+ fish in vegetated habitats and adults in open water. From mid-July to late August, some 0+ co-occurred with adults, but most 0+ fishes remained in vegetated areas. Finally, from late August to mid-October, most fish (both 0+ and adults) left the vegetation for unvegetated littoral habitats, the exception being fish species known to be dependent on macrophytes.
4. Contrary to patterns for adult fishes, the 0+ fish assemblage was dynamic. These dynamics were driven by ontogenetic species-specific habitat changes. Consequently, there was little evidence of stable assemblages or strong assemblage–habitat relationships that would be expected of an 'interactive' assemblage. It is likely that the patterns observed are a result of species-specific response to habitat availability in the lake.     

Effects of eucalypt nutritional quality on the Bog gum‐Victorian metapopulation of Ctenarytaina bipartita and implications for host and range expansion

1. Novel hosts present phytophagous insects with nutritional challenges which can cause host‐associated divergence. 2. The performance of the Bog gum‐Victorian metapopulation of Ctenarytaina bipartita Burckhardt et al. (Psylloidea:Aphalaridae), a psyllid whose range is being expanded by tree planting, on five species and genotypes of Eucalyptus endemic to south‐eastern Australia was quantified. Settling of females on two non‐hosts was also tested. 3. Female C. bipartita exhibited significant host‐associated plasticity in proctiger length (the body part used for oviposition into apical buds). Psyllids with longer wings and proctigers arose from a primary host. Fecundity varied significantly among hosts and was highest on a novel host. Hosts did not differ significantly in free amino acids (FAAs) but did differ in concentrations of essential amino acids (EAAs). However, nymphs did not differ significantly in EAAs. Surprisingly, fecundity was not related to total FAAs, availability of EAAs or concentrations of EAAs but was related to concentrations of four non‐EAAs. Mean fecundity per host was also positively related to the relative abundance of galloyl groups (associated with hydrolysable tannins). 4. Leaf age was more important to settling than eucalypt species; females settled on young leaves but this response was not related to leaf water content. 5. Planting the rare Eucalyptus kitsoniana in new habitats will expand the range of Bog gum‐Victorian C. bipartita and provide a bridge for the colonisation of novel eucalypts with buds suitable for oviposition. Host expansion by this metapopulation is not constrained by nutritional quality and may result in morphological divergence.     

Tritrichomonas mobilensis n. sp. (Zoomastigophorea: Trichomonadida) from the Bolivian Squirrel Monkey Saimiri boliviensis boliviensis1

ABSTRACT. A trichomonad flagellate, Tritrichomonas mobilensis n. sp., is described from the large intestine of the squirrel monkey, Saimiri boliviensis boliviensis. The organism has a lanceolate body 7–10.5 μm in length; a well developed undulating membrane; a stout, tubular axostyle with periaxostylar rings that terminate in a cone-shaped segment projecting from the posterior end of the cell; and a moderately wide costa. The anterior flagella are about as long as the body, and the recurrent flagellum is of the acroneme type. All its characteristics suggest that the new species belongs in the Tritrichomonas augusta type of the subfamily Tritrichomonadinae.     

Endocrine regulation of female contact sex pheromone production in the German cockroach, Blattella germanica

ABSTRACT The amount of the major component of the cuticular sex pheromone, 3, 11-dimethyl-2-nonacosanone, on individual female German cockroaches, Blattella germanica (L.), as a function of age was determined by gas-liquid-chromatographic analysis. Accumulation of phermone increased with age in both virgin and mated females. During the first gono-trophic cycle, the pheromone accumulated most rapidly when oocyte growth rates were maximal (days 5–10), and least rapidly while the female carried an ootheca (days 11–32). Pheromone accumulation was similar in virgin and mated females when the same physiological stages (determined by oocyte maturation) were considered. Inhibition of Juvenile Hormone release, through allatectomy, chemicals (precocene or fluoromevalonate), or through mechanical egg case implants, suppressed or delayed pheromone production and oocyte growth. The Juvenile Hormone analogue ZR512 induced allatectomized or head-ligated females and females with chemically or mechanically inhibited corpora allata to produce pheromone and enlarge their basal oocytes. Finally, ZR512 applied to intact females stimulated pheromone production in a dose-dependent manner.     

Clonal Aspects of the C-type Virus-releasing Cells of a Cultured Human Rhabdomyosarcoma Line (RD 114) <Emphasis Type="Italic">in vitro</Emphasis>

WE have recently reported the successful transplantation of human cancer cells in cats¹. Foetuses were inoculated through the maternal uterine wall with cultured human rhabdomyosarcoma cells, RD line No. 2 and disseminated rhabdomyosarco-mata were noted in the kittens after birth. (As previously described², before the first biopsy and the derivation of line No. 1, the patient had been treated with large doses of cyclophosphamide and, before the second biopsy and the initiation of line No. 2, received both cyclophosphamide and X-irradiation.)