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.     

Actions of platelet-derived growth factor isoforms in mesangial cells

Platelet-derived growth factor (PDGF) occurs as homodimers or heterodimers of related polypeptide chains PDGF-BB, -AA, and -AB. There are two receptors that bind PDGF, termed alpha and beta. The beta receptor recognizes PDGF B chain and is dimerized in response to PDGF BB. The alpha receptor recognizes PDGF B as well as A chains and can be dimerized by the three dimeric forms of PDGF AA, AB, and BB. To characterize PDGF receptor signaling mechanisms and biologic activities in human mesangial cells (MC), we explored the effects of the three PDGF isoforms on DNA synthesis, phospholipase C activation, and PDGF protooncogene induction. PDGF-BB homodimer and AB heterodimer induced a marked increase in DNA synthesis, activation of phsopholipase C, and autoinduction of PDGF A and B chain mRNAs, whereas PDGF-AA homodimer was without effect. The lack of response to PDGF AA could be accounted for by down regulation of the PDGF-alpha receptor since preincubation of MC with suramin restored PDGF AA-induced DNA synthesis. Ligand binding studies demonstrate specific binding of labeled PDGF BB and AB and to a lower extent PDGF AA isoforms to mesangial cells. These results are consistent with predominant expression of PDGF beta receptor in MC, which is linked to phospholipase-C activation. The potent biologic effects of PDGF-AB heterodimer in cells that express very few alpha receptors and do not respond to PDGF AA are somewhat inconsistent with the currently accepted model of PDGF receptor interaction and suggest the presence of additional mechanisms for PDGF isoform binding and activation. © 1994 Wiley-Liss, Inc.     

Statins Improve the Resolution of Established Murine Venous Thrombosis: Reductions in Thrombus Burden and Vein Wall Scarring

Despite anticoagulation therapy, up to one-half of patients with deep vein thrombosis (DVT) will develop the post-thrombotic syndrome (PTS). Improving the long-term outcome of DVT patients at risk for PTS will therefore require new approaches. Here we investigate the effects of statins—lipid-lowering agents with anti-thrombotic and anti-inflammatory properties—in decreasing thrombus burden and decreasing vein wall injury, mediators of PTS, in established murine stasis and non-stasis chemical-induced venous thrombosis (N = 282 mice). Treatment of mice with daily atorvastatin or rosuvastatin significantly reduced stasis venous thrombus burden by 25% without affecting lipid levels, blood coagulation parameters, or blood cell counts. Statin-driven reductions in VT burden (thrombus mass for stasis thrombi, intravital microscopy thrombus area for non-stasis thrombi) compared similarly to the therapeutic anticoagulant effects of low molecular weight heparin. Blood from statin-treated mice showed significant reductions in platelet aggregation and clot stability. Statins additionally reduced thrombus plasminogen activator inhibitor-1 (PAI-1), tissue factor, neutrophils, myeloperoxidase, neutrophil extracellular traps (NETs), and macrophages, and these effects were most notable in the earlier timepoints after DVT formation. In addition, statins reduced DVT-induced vein wall scarring by 50% durably up to day 21 in stasis VT, as shown by polarized light microscopy of picrosirius red-stained vein wall collagen. The overall results demonstrate that statins improve VT resolution via profibrinolytic, anticoagulant, antiplatelet, and anti-vein wall scarring effects. Statins may therefore offer a new pharmacotherapeutic approach to improve DVT resolution and to reduce the post-thrombotic syndrome, particularly in subjects who are ineligible for anticoagulation therapy.     

Genetic diversity of chloroquine-resistant Plasmodium vivax parasites from the western Brazilian Amazon

The molecular basis of Plasmodium vivax chloroquine (CQ) resistance is still unknown. Elucidating the molecular background of parasites that are sensitive or resistant to CQ will help to identify and monitor the spread of resistance. By genotyping a panel of molecular markers, we demonstrate a similar genetic variability between in vitro CQ-resistant and sensitive phenotypes of P. vivax parasites. However, our studies identified two loci (MS8 and MSP1-B10) that could be used to discriminate between both CQ-susceptible phenotypes among P. vivax isolates in vitro. These preliminary data suggest that microsatellites may be used to identify and to monitor the spread of P. vivax-resistance around the world.     

地塞美松中间体的C1,4脱氢和11α-羟基化

地塞美松 (Ｄｅｘａｍｅｔｈａｓｏｎｅ)为高效肾上腺皮质激素药物 ,临床上广泛使用。开拓用梯可吉宁 (Ｔｉｇｏｇｅｎｉｎ)为起始原料生产从化学结构和合成技术上讲较为合理 ,而且适合于资源综合利用[1] 。在合成过程中 ,除了Ａ环需引入Ｃ1,2 和Ｃ4 ,5两个双键 (含Ｃ-3 羟基氧化 )外 ,还需用微生物法在Ｃ-11位引入羟基。国外常采用化学法脱氢 ,然后再用霉菌 11α 羟基化[2 ,3 ] 。本文报道用两类微生物菌种 ,节杆菌 (Ａｒｔｈｒｏｂａｃｔｅｒｓｐ .)ＡＸ86和绿僵菌 (Ｍｅｔａｒｈｉｚｉｕｍｓｐ .)Ｍ 88,混合转化一步完成脱氢和羟基化反应…     

A correlation between BCL-2 modifying factor,p53 and livin gene expressions in cancer colon patients

Accumulating evidence has revealed that livin gene and BCL-2 modifying factor (BMF) gene are closely associated with the initiation and progression of colon carcinoma by activating or suppressing multiple malignant processes. Those genes that can detect colon - cancer are a promising approach for cancer screening and diagnosis. This study aimed to evaluate correlation between livin, BMF and p53 genes expression in colon cancer tissues of patients included in the study, and their relationship with clinicopathological features and survival outcome in those patients. In this study, 50 pathologically diagnosed early cancer colon patients included and their tissue biopsy with 50 matched adjacent normal tissue, and 50 adenoma tissue specimens were analyzed for livin gene and BMF gene expressions using real time PCR. The relationship of those genes expressions with clinicopathological features, tumor markers, Time to Progression and overall survival for those patients were correlated in cancer colon group. In this study, there was a significant a reciprocal relationship between over expression of livin gene and down regulation of BMF and p53 genes in colon cancer cells. Livin mRNA was significantly higher, while BMF and p53 mRNA were significantly lower in colorectal cancer tissue compared to benign and normal colon tissue specimens (P < 0.001), however, this finding was absent between colon adenomas and normal mucosa. There was a significant association between up regulation of livin and down regulation of BMF and p53 expressions with more aggressive tumor (advanced TNM stage), rapid progression with metastasis and decreased overall survival in cancer colon patients, hence these genes can serve as significant prognostic markers of poor outcome in colon cancer patients. This work highlights the role of livin, BMF and p53 genes in colorectal tumorigenesis and the applicability of using those genes as a diagnostic and prognostic markers in patients with colon carcinoma and as a good target for cancer colon treatment in the future.     

A novel small molecule HSP90 inhibitor,NXD30001, differentially induces heat shock proteins in nervous tissue in culture and in vivo

Heat shock proteins (HSPs) are attractive therapeutic targets for neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), characterized by aberrant formation of protein aggregates. Although motor neurons have a high threshold for activation of HSP genes, HSP90 inhibitors are effective inducers. This study evaluated NXD30001, a novel, small molecule HSP90 inhibitor based on the radicicol backbone, for its ability to induce neuronal HSPs and for efficacy in an experimental model of ALS based on mutations in superoxide-dismutase 1 (SOD1). In motor neurons of dissociated murine spinal cord cultures, NXD30001-induced expression of HSP70/HSPA1 (iHSP70) and its co-chaperone HSP40/DNAJ through activation of HSF1 and exhibited a protective profile against SOD1^G93A similar to geldanamycin, but with less toxicity. Treatment prevented protein aggregation, mitochondrial fragmentation, and motor neuron death, important features of mutant SOD1 toxicity, but did not effectively prevent aberrant intracellular Ca²⁺ accumulation. NXD30001 distributed to brain and spinal cord of wild-type and SOD1^G93A transgenic mice following intraperitoneal injection; however, unlike in culture, in vivo levels of SOD1 were not reduced. NXD30001-induced expression of iHSP70 in skeletal and cardiac muscle and, to a lesser extent, in kidney, but not in liver, spinal cord, or brain, with either single or repeated administration. NXD30001 is a very useful experimental tool in culture, but these data point to the complex nature of HSP gene regulation in vivo and the necessity for early evaluation of the efficacy of novel HSP inducers in target tissues in vivo.     

Environmental controls over carbon exchange of three forest ecosystems in eastern China

Net ecosystem productivity (NEP) was continuously measured using the eddy covariance (EC) technique from 2003 to 2005 at three forest sites of ChinaFLUX. The forests include Changbaishan temperate mixed forest (CBS), Qianyanzhou subtropical coniferous plantation (QYZ), and Dinghushan subtropical evergreen broad‐leaved forest (DHS). They span wide ranges of temperature and precipitation and are influenced by the eastern Asian monsoon climate to varying extent. In this study, we estimated ecosystem respiration (RE) and gross ecosystem productivity (GEP). Comparison of ecosystem carbon exchange among the three forests shows that RE was mainly determined by temperature, with the forest at CBS exhibiting the highest temperature sensitivity among the three ecosystems. The RE was highly dependent on GEP across the three forests, and the ratio of RE to GEP decreased along the North–South Transect of Eastern China (NSTEC) (i.e. from the CBS to the DHS), with an average of 0.77 ± 0.06. Daily GEP was mainly influenced by temperature at CBS, whereas photosynthetic photon flux density was the dominant factor affecting the daily GEP at both QYZ and DHS. Temperature mainly determined the pattern of the interannual variations of ecosystem carbon exchange at CBS. However, water availability primarily controlled the interannual variations of ecosystem carbon exchange at QYZ. At DHS, NEP attained the highest values at the beginning of the dry seasons (autumn) rather than the rainy seasons (summer), probably because insufficient radiation and frequent fog during the rainy seasons hindered canopy photosynthesis. All the three forest ecosystems acted as a carbon sink from 2003 to 2005. The annual average values of NEP at CBS, QYZ, and DHS were 259 ± 19, 354 ± 34, and 434 ± 66 g C m⁻² yr⁻¹, respectively. The slope of NEP that decreased with increasing latitude along the NSTEC was markedly different from that observed on the forest transect in the European continent. Long‐term flux measurements over more forest ecosystems along the NSTEC will further help verify such a difference between the European forest transect and the NSTEC and provide insights into the responses of ecosystem carbon exchange to climate change in China.