An acylatable residue of Hedgehog is differentially required in Drosophila and mouse limb development

The Drosophila Hedgehog protein and its vertebrate counterpart Sonic hedgehog are required for a wide variety of patterning events throughout development. Hedgehog proteins are secreted from cells and undergo autocatalytic cleavage and cholesterol modification to produce a mature signaling domain. This domain of Sonic hedgehog has recently been shown to acquire an N-terminal acyl group in cell culture. We have investigated the in vivo role that such acylation might play in appendage patterning in mouse and Drosophila; in both species Hedgehog proteins define a posterior domain of the limb or wing. A mutant form of Sonic hedgehog that cannot undergo acylation retains significant ability to repattern the mouse limb. However, the corresponding mutation in Drosophila Hedgehog renders it inactive in vivo, although it is normally processed. Furthermore, overexpression of the mutant form has dominant negative effects on Hedgehog signaling. These data suggest that the importance of the N-terminal cysteine of mature Hedgehog in patterning appendages differs between species.     

Multiple histone modifications in euchromatin promote heterochromatin formation by redundant mechanisms in Saccharomyces cerevisiae

Background  

Methylation of lysine 79 on histone H3 by Dot1 is required for maintenance of heterochromatin structure in yeast and humans. However, this histone modification occurs predominantly in euchromatin. Thus, Dot1 affects silencing by indirect mechanisms and does not act by the recruitment model commonly proposed for histone modifications. To better understand the role of H3K79 methylation gene silencing, we investigated the silencing function of Dot1 by genetic suppressor and enhancer analysis and examined the relationship between Dot1 and other global euchromatic histone modifiers.     

Unequal synthesis and differential degradation of propionyl CoA carboxylase subunits in cells from normal and propionic acidemia patients.

We have characterized further the molecular basis of human inherited propionyl CoA carboxylase deficiency by measuring steady state levels of the mRNAs coding for the enzyme's two protein subunits (alpha and beta) and by estimating initial synthesis and steady state levels of the protein subunits in skin fibroblasts from controls and affected patients. We studied cell lines from both major complementation groups (pccA and pccBC) corresponding, respectively, to defects in the carboxylase's alpha and beta subunits. Analysis of pccA lines revealed the absence of alpha chain mRNA in three and an abnormally small alpha-mRNA in a fourth. Despite the presence of normal beta-mRNA in each of these pccA lines, there was complete absence of both alpha and beta protein subunits under steady state conditions, even though new synthesis and mitochondrial import of beta precursors was normal. Results in nine pccBC lines revealed normal alpha mRNA in each, while the amounts of beta-mRNA were distinctly reduced in every case. Correspondingly, alpha protein subunits were present in normal amounts at steady-state, but beta subunits were uniformly decreased. In addition, in six of the nine beta deficient cell lines, partially degraded beta-subunits were observed. To help interpret these results, synthesis and stability of carboxylase subunits were studied in intact HeLa cells using a pulse-chase protocol. Whereas alpha chains were stable over the four hour interval studied, beta chains--initially synthesized in large excess over alpha chains--were degraded rapidly reaching equivalence with alpha chains after two hours.(ABSTRACT TRUNCATED AT 250 WORDS)     

Maturation of Borna disease virus glycoprotein

The maturation of Borna disease virus (BDV) glycoprotein GP was studied in regard to intracellular compartmentalization, compartmentalization signal-domains, proteolytic processing, and packaging into virus particles. Our data show that BDV-GP is (i) predominantly located in the endoplasmic reticulum (ER), (ii) partially exists in the ER already as cleaved subunits GP-N and GP-C, (iii) is directed to the ER/cis-Golgi region by its transmembrane and/or cytoplasmic domains in CD8-BDV-GP hybrid constructs and (iv) is incorporated in the virus particles as authentic BDV glycoprotein exclusively in the cleaved form decorated with N-glycans of the complex type. Downregulation of BDV-glycoproteins on the cell surface, their limited proteolytic processing, and protection of antigenic epitopes on the viral glycoproteins by host-identical N-glycans are different strategies for persistent virus infections.     

Simulating the Distribution of Individual Livestock Farms and Their Populations in the United States: An Example Using Domestic Swine (Sus scrofa domesticus) Farms

Livestock distribution in the United States (U.S.) can only be mapped at a county-level or worse resolution. We developed a spatial microsimulation model called the Farm Location and Agricultural Production Simulator (FLAPS) that simulated the distribution and populations of individual livestock farms throughout the conterminous U.S. Using domestic pigs (Sus scrofa domesticus) as an example species, we customized iterative proportional-fitting algorithms for the hierarchical structure of the U.S. Census of Agriculture and imputed unpublished state- or county-level livestock population totals that were redacted to ensure confidentiality. We used a weighted sampling design to collect data on the presence and absence of farms and used them to develop a national-scale distribution model that predicted the distribution of individual farms at a 100 m resolution. We implemented microsimulation algorithms that simulated the populations and locations of individual farms using output from our imputed Census of Agriculture dataset and distribution model. Approximately 19% of county-level pig population totals were unpublished in the 2012 Census of Agriculture and needed to be imputed. Using aerial photography, we confirmed the presence or absence of livestock farms at 10,238 locations and found livestock farms were correlated with open areas, cropland, and roads, and also areas with cooler temperatures and gentler topography. The distribution of swine farms was highly variable, but cross-validation of our distribution model produced an area under the receiver-operating characteristics curve value of 0.78, which indicated good predictive performance. Verification analyses showed FLAPS accurately imputed and simulated Census of Agriculture data based on absolute percent difference values of < 0.01% at the state-to-national scale, 3.26% for the county-to-state scale, and 0.03% for the individual farm-to-county scale. Our output data have many applications for risk management of agricultural systems including epidemiological studies, food safety, biosecurity issues, emergency-response planning, and conflicts between livestock and other natural resources.     

The effect of glucagon on the kinetics of hepatic mitochondrial calcium uptake

Summary Previous work by this and other laboratories has shown that glucagon administration stimulates calcium uptake by subsequently isolated hepatic mitochondria. This stimulation of hepatic mitochondrial Ca²⁺ uptake byin vivo administration of glucagon was further characterized in the present report. Maximal stimulation of mitochondrial Ca²⁺ accumulation was achieved between 6–10 min after the intravenous injection of glucagon into intact rats. Under control conditions, Ca²⁺ uptake was inhibited by the presence of Mg²⁺ in the incubation medium. Glucagon treatment, however, appeared to obliterate the observed inhibition by Mg²⁺ of mitochondrial Ca²⁺ uptake. Kinetic experiments revealed the usual sigmoidicity associated with initial velocity curves for mitochondrial calcium uptake. Glucagon treatment did not alter this sigmoidal relationship. Glucagon treatment significantly increased the V_max for Ca²⁺ uptake from 292±22 to 377±34 nmoles Ca²⁺ /min per mg protein (n=8) but did not affect the K_0.5, (6.5–8.6 μM). Since the major kinetic change in mitochondrial Ca²⁺ uptake evoked by glucagon is an increase in V_max, the enhancement mechanism is likely to be an increase either in the number of active transport sites available to Ca²⁺ or in the rate of Ca²⁺ carrier movement across the mitochondrial membranes.     

Greenhouse gas emissions and global warming potential of traditional and diversified tropical rice rotation systems

Global rice agriculture will be increasingly challenged by water scarcity, while at the same time changes in demand (e.g. changes in diets or increasing demand for biofuels) will feed back on agricultural practices. These factors are changing traditional cropping patterns from double‐rice cropping to the introduction of upland crops in the dry season. For a comprehensive assessment of greenhouse gas (GHG) balances, we measured methane (CH₄)/nitrous oxide (N₂O) emissions and agronomic parameters over 2.5 years in double‐rice cropping (R‐R) and paddy rice rotations diversified with either maize (R‐M) or aerobic rice (R‐A) in upland cultivation. Introduction of upland crops in the dry season reduced irrigation water use and CH₄ emissions by 66–81% and 95–99%, respectively. Moreover, for practices including upland crops, CH₄ emissions in the subsequent wet season with paddy rice were reduced by 54–60%. Although annual N₂O emissions increased two‐ to threefold in the diversified systems, the strong reduction in CH₄ led to a significantly lower (P < 0.05) annual GWP (CH₄ + N₂O) as compared to the traditional double‐rice cropping system. Measurements of soil organic carbon (SOC) contents before and 3 years after the introduction of upland crop rotations indicated a SOC loss for the R‐M system, while for the other systems SOC stocks were unaffected. This trend for R‐M systems needs to be followed as it has significant consequences not only for the GWP balance but also with regard to soil fertility. Economic assessment showed a similar gross profit span for R‐M and R‐R, while gross profits for R‐A were reduced as a consequence of lower productivity. Nevertheless, regarding a future increase in water scarcity, it can be expected that mixed lowland–upland systems will expand in SE Asia as water requirements were cut by more than half in both rotation systems with upland crops.     

Workers dominate male production in the neotropical bumblebee Bombus wilmattae (Hymenoptera: Apidae)

Background

Cooperation and conflict in social insects are closely linked to the genetic structure of the colony. Kin selection theory predicts conflict over the production of males between the workers and the queen and between the workers themselves, depending on intra-colonial relatedness but also on other factors like colony efficiency, sex ratios, cost of worker reproduction and worker dominance behaviour. In most bumblebee (Bombus) species the queen wins this conflict and often dominates male production. However, most studies in bumblebees have been conducted with only a few selected, mostly single mated species from temperate climate regions. Here we study the genetic colony composition of the facultative polyandrous neotropical bumblebee Bombus wilmattae, to assess the outcome of the queen-worker conflict over male production and to detect potential worker policing.

Results

A total of 120 males from five colonies were genotyped with up to nine microsatellite markers to infer their parentage. Four of the five colonies were queen right at point of time of male sampling, while one had an uncertain queen status. The workers clearly dominated production of males with an average of 84.9% +/- 14.3% of males being worker sons. In the two doubly mated colonies 62.5% and 96.7% of the male offspring originated from workers and both patrilines participated in male production. Inferring the mother genotypes from the male offspring, between four to eight workers participated in the production of males.

Conclusions

In this study we show that the workers clearly win the queen-worker conflict over male production in B. wilmattae, which sets them apart from the temperate bumblebee species studied so far. Workers clearly dominated male production in the singly as well the doubly mated colonies, with up to eight workers producing male offspring in a single colony. Moreover no monopolization of reproduction by single workers occurred.     

Association between 8-hydroxy-2'-deoxyguanosine levels in DNA of workers highly exposed to asbestos and their clinical data, occupational and non-occupational confounding factors, and cancer

In the preceding paper [B. Marczynski, P. Rozynek, T. Kraus, St. Schl?sser, H.J. Raithel, X. Baur, Levels of 8-hydroxy-2'-deoxyguanosine in DNA of white blood cells from workers highly exposed to asbestos in Germany, Mutat. Res. (2000) submitted] we described significant increases (p<0.001) in the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) adducts in the DNA of white blood cells (WBC) of workers highly exposed to asbestos fibers at the workplace relative to those found in the control group in all three study years (period between 1994 and 1997). The results show that the oxidative DNA damage in exposed individuals is between 1.7 times and twice that found in control samples for all 3 years of the study (p<0.001). The aim of this study was to examine the association between the 8-OHdG levels in WBC DNA of workers highly exposed to asbestos fibers at the workplace and clinical data, occupational and non-occupational confounding factors, and cancer. There is no obvious correlation between the steady-state levels of 8-OHdG in the circulating WBC DNA of asbestos workers and possible confounding factors, such as the presence of benign asbestos-associated diseases, the duration of asbestos exposure, the latency period, the fixed cumulative fibrous dust dose ("fiber years"), age, smoking status, acute febrile infections, medicines, aspirin, calcium (Ca(2+)), magnesium (Mg(2+)), and the hormone and vitamin intake. This indicates that previous inhalation of asbestos fibers is the major factor responsible for the difference observed in oxidative DNA damage between asbestos workers and controls. For patients suffering from respiratory cancer, cancer of the gastrointestinal tract, mouth/pharynx/larynx, and urogenital tract the mean DNA-adduct level was significantly higher (p<0.01) than that found in controls, but not significantly higher (p>0.05) than that for asbestos-exposed patients without tumours. The formation of 8-OHdG adduct levels in WBC DNA of patients with hematopoietic cancer, chondrosarcomas and multiform glioblastomas was not significantly higher than that found in the control group (p>0.05). Our results support the hypothesis that oxidative DNA damage in man caused by asbestos fibers plays a role in the formation of malignant tumours.