A Disjunct Argentine Ant Metacolony in Macaronesia and Southwestern Europe

The Argentine ant, Linepithema humile, originally from South America, is now a major pest in many parts of the world with Mediterranean-like climates. Earlier research indicated that southwestern European L. humile populations are segregated into two distinct supercolonies, the ‘Main’ supercolony extending through Portugal, Spain, southern France, and Italy, and the ‘Catalonian’ supercolony in eastern Spain. Both supercolonies are unicolonial, with workers showing no aggression towards members of the same supercolony, but severe aggression towards members of the other supercolony. Here we evaluated the behavioral relationships among non-native L. humile populations on the Macaronesian islands of Madeira and the Azores and non-native populations in southwestern Europe. We conducted aggression assays among L. humile workers from Madeira, the Azores, and the two southwestern European supercolonies. We found no aggressive interactions among any combination of workers from Madeira, the Azores, and the Main supercolony. However, workers from Madeira and the Azores always fought aggressively with workers from the Catalonian supercolony. Thus, the populations of L. humile in Madeira and the Azores appear to be unicolonial and act as if they belong to the Main supercolony of southwestern Europe. This set of geographically separated but mutually compatible supercolonies, which we term a ‘metacolony,’ appears to descend from one supercolony. Historical evidence suggests that the first L. humile population in the greater Mediterranean region was established in Madeira and that propagules from the dominant supercolony in Madeira gave rise to the dominant supercolonies in to other parts of the region.     

Where Are Socioeconomically Deprived Immigrants Located in Chile? A Spatial Analysis of Census Data Using an Index of Multiple Deprivation from the Last Three Decades (1992-2012)

Introduction and Purpose of the Study

Immigrants in Chile have diverse characteristics and include socioeconomically deprived populations. The location of socioeconomically deprived immigrants is important for the development of public policy intelligence at the local and national levels but their areas of residence have not been mapped in Chile. This study explored the spatial distribution of socioeconomic deprivation among immigrants in Chile, 1992–2012, and compared it to the total population.

Material and Methods

Areas with socioeconomically deprived populations were identified with a deprivation index which we developed modelled upon the Index of Multiple Deprivation (IMD) for England. Our IMD was based upon the indicators of unemployment, low educational level (primary) and disability from Census data at county level for the three decades 1992, 2002 and 2012, for 332, 339 and 343 counties respectively. We developed two versions of the IMD one based on disadvantage among the total population and another focused upon the circumstances of immigrants only. We generated a spatial representation of the IMD using GIS, for the overall IMD score and for each dimension of the index, separately. We also compared the immigrants´ IMD to the total population´s IMD using Pearson´s correlation test.

Results

Results showed that socioeconomically deprived immigrants tended to be concentrated in counties in the northern and central area of Chile, in particular within the Metropolitan Region of Santiago. These were the same counties where there was the greatest concentration of socioeconomic deprivation for the total population during the same time periods. Since 1992 there have been significant change in the location of the socioeconomically deprived populations within the Metropolitan Region of Santiago with the highest IMD scores for both the total population and immigrants becoming increasingly concentrated in the central and eastern counties of the Region.

Conclusion

This is the first study analysing the spatial distribution of socioeconomic deprivation among international immigrants and the total population in a Latin American country. Findings could inform policy makers about location of areas of higher need of social protection in Chile, for both immigrants and the total resident population in the country.     

Cysteine pK(a) values for the bacterial peroxiredoxin AhpC

Salmonella typhimurium AhpC is a founding member of the peroxiredoxin family, a ubiquitous group of cysteine-based peroxidases with high reactivity toward hydrogen peroxide, organic hydroperoxides, and peroxynitrite. For all of the peroxiredoxins, the catalytic cysteine, referred to as the peroxidatic cysteine (C(P)), acts as a nucleophile in attacking the peroxide substrate, forming a cysteine sulfenic acid at the active site. Because thiolates are far stronger nucleophiles than thiol groups, it is generally accepted that cysteine-based peroxidases should exhibit pK(a) values lower than an unperturbed value of 8.3-8.5. In this investigation, several independent approaches were used to assess the pK(a) of the two cysteinyl residues of AhpC. Methods using two different iodoacetamide derivatives yielded unperturbed pK(a) values (7.9-8.7) for both cysteines, apparently due to reactivity with the wrong conformation of C(P) (i.e., locally unfolded and flipped out of the active site), as supported by X-ray crystallographic analyses. A functional pK(a) of 5.94 +/- 0.10 presumably reflecting the titration of C(P) within the fully folded active site was obtained by measuring AhpC competition with horseradish peroxidase for hydrogen peroxide; this value is quite similar to that obtained by analyzing the pH dependence of the epsilon(240) of wild-type AhpC (5.84 +/- 0.02) and similar to those obtained for two typical 2-cysteine peroxiredoxins from Saccharomyces cerevisiae (5.4 and 6.0). Thus, the pK(a) value of AhpC balances the need for a deprotonated thiol (at pH 7, approximately 90% of the C(P) would be deprotonated) with the fact that thiolates with higher pK(a) values are stronger nucleophiles.     

Chlorophyllide a Oxygenase mRNA and Protein Levels Correlate with the Chlorophyll a/b Ratio in Arabidopsis thaliana

Plants can change the size of their light harvesting complexes in response to growth at different light intensities. Although these changes are small compared to those observed in algae, their conservation in many plant species suggest they play an important role in photoacclimation. A polyclonal antibody to the C-terminus of the Arabidopsis thaliana chlorophyllide a oxygenase (CAO) protein was used to determine if CAO protein levels change under three conditions which perturb chlorophyll levels. These conditions were: (1) transfer to shaded light intensity; (2) limited chlorophyll synthesis, and (3) during photoinhibition. Transfer of wild-type plants from moderate to shaded light intensity resulted in a slight reduction in the Chl a/b ratio, and increases in both CAO and Lhcb1 mRNA levels as well as CAO protein levels. CAO protein levels were also measured in the cch1 mutant, a P642L missense mutation in the H subunit of Mg-chelatase. This mutant has reduced total Chl levels and an increased Chl a/b ratio when transferred to moderate light intensity. After transfer to moderate light intensity, CAO mRNA levels decreased in the cch1 mutant, and a concomitant decrease in CAO protein levels was also observed. Measurements of tetrapyrrole intermediates suggested that decreased Chl synthesis in the cch1 mutant was not a result of increased feedback inhibition at higher light intensity. When wild-type plants were exposed to photoinhibitory light intensity for 3 h, total Chl levels decreased and both CAO mRNA and CAO protein levels were also reduced. These results indicate that CAO protein levels correlate with CAO mRNA levels, and suggest that changes in Chl b levels in vascular plants, are regulated, in part, at the CAO mRNA level.     

Mass‐trapping trials for the control of pine processionary moth in a pine woodland recreational area

The pine processionary moth, Thaumetopoea pityocampa, causes serious defoliation to Cedrus, Pinus and Pseudotsuga trees, as well as health problems in humans, pets and farm animals due to their urticating hairs. Environmentally friendly strategies for the management of T. pityocampa include: removal of egg batches, removal of nests, trapping of migrant larvae, spraying microbial or Insect Growth Regulator (IGR) insecticides and biocontrol, as well as pheromone‐based adult trapping and mating‐disruption. In the present paper, results on innovative technology for the control of T. pityocampa infestation using pheromone mass‐trapping are reported. Two 1‐ha plots were identified in the study area (central‐south Italy), a pine woodland recreational site growing Pinus halepensis. In the experimental plot (MT‐plot), 10 G‐traps (funnel trap type) baited with (Z)‐13‐hexadecen‐11‐ynyl acetate sex pheromone component were placed for mass‐trapping of adults; the other plot was used as a control‐plot (C‐plot). The T. pityocampa population was monitored using the two central traps in the MT‐plot and two traps positioned in the C‐plot. In addition, the winter nests made by T. pityocampa larvae overwintering on pine trees were counted. After 2 years of mass‐trapping, the number of adults trapped by the monitoring pheromone traps decreased in the MT‐plot, but not in the C‐plot, whereas the number of nests decreased in both plots. Statistical results highlighted significant differences in trap catches between the two plots but not between years. In the case of nests, differences among plots were not significant before the mass‐trapping, but significant after 1‐year treatment. According to our results, the mass‐trapping technique is able to reduce T. pityocampa infestations. This pheromone method can be applied in combination with other control systems in the context of integrated pest management in recreational areas.     

The anaphase-promoting complex/cyclosome inhibitor Emi2 is essential for meiotic but not mitotic cell cycles

Vertebrate oocytes awaiting fertilization are arrested at metaphase of meiosis II by cytostatic factor (CSF). This arrest is due to inhibition of the anaphase-promoting complex/cyclosome, in part by a newly identified protein, Emi2 (xErp1). Emi2 is required for maintenance of CSF arrest in egg extracts, but its function in CSF establishment in oocytes and the normal embryonic cell cycle is unknown. Here we show that during oocyte maturation, Emi2 appears only after metaphase I, and its level peaks at CSF arrest (metaphase II). In M phase, Emi2 undergoes a phosphorylation-dependent electrophoretic shift. Microinjection of antisense oligonucleotides against Emi2 into stage VI oocytes blocks progression through meiosis II and the establishment of CSF arrest. Recombinant Emi2 rescues CSF arrest in these oocytes and also causes CSF arrest in egg extracts and in blastomeres of two-cell embryos. Fertilization triggers rapid, complete degradation of Emi2, but it is resynthesized in the first embryonic cell cycle to reach levels 5-fold lower than during CSF arrest. However, depletion of the protein from cycling egg extracts does not prevent mitotic cell cycle progression. Thus, Emi2 plays an essential role in meiotic but not mitotic cell cycles.     

Origin and Diet of the Prehistoric Hunter-Gatherers on the Mediterranean Island of Favignana (ègadi Islands,Sicily)

Hunter-gatherers living in Europe during the transition from the late Pleistocene to the Holocene intensified food acquisition by broadening the range of resources exploited to include marine taxa. However, little is known on the nature of this dietary change in the Mediterranean Basin. A key area to investigate this issue is the archipelago of the Ègadi Islands, most of which were connected to Sicily until the early Holocene. The site of Grotta d’Oriente, on the present-day island of Favignana, was occupied by hunter-gatherers when Postglacial environmental changes were taking place (14,000-7,500 cal BP). Here we present the results of AMS radiocarbon dating, palaeogenetic and isotopic analyses undertaken on skeletal remains of the humans buried at Grotta d’Oriente. Analyses of the mitochondrial hypervariable first region of individual Oriente B, which belongs to the HV-1 haplogroup, suggest for the first time on genetic grounds that humans living in Sicily during the early Holocene could have originated from groups that migrated from the Italian Peninsula around the Last Glacial Maximum. Carbon and nitrogen isotope analyses show that the Upper Palaeolithic and Mesolithic hunter-gatherers of Favignana consumed almost exclusively protein from terrestrial game and that there was only a slight increase in marine food consumption from the late Pleistocene to the early Holocene. This dietary change was similar in scale to that at sites on mainland Sicily and in the rest of the Mediterranean, suggesting that the hunter-gatherers of Grotta d’Oriente did not modify their subsistence strategies specifically to adapt to the progressive isolation of Favignana. The limited development of technologies for intensively exploiting marine resources was probably a consequence both of Mediterranean oligotrophy and of the small effective population size of these increasingly isolated human groups, which made innovation less likely and prevented transmission of fitness-enhancing adaptations.     

Determinants of Survival in Malignant Pleural Mesothelioma: A Surveillance,Epidemiology, and End Results (SEER) Study of 14,228 Patients

Introduction

Left untreated, malignant pleural mesothelioma (MPM) is associated with uniformly poor prognosis. Better survival has been reported with surgery-based multimodality therapy, but to date, no trial has demonstrated survival benefit of surgery over other therapies. We evaluated whether cancer-directed surgery influenced survival independently from other predictors in a large population-based dataset.

Methods

The SEER database was explored from 1973 to 2009 to identify all cases of pathologically-proven MPM. Age, sex, race, year of diagnosis, histology stage, cancer-directed surgery, radiation, and vital status were analyzed. The association between prognostic factors and survival was estimated using Cox regression and propensity matched analysis.

Results

There were 14,228 patients with pathologic diagnosis of MPM. On multivariable analysis, female gender, younger age, early stage, and treatment with surgery were independent predictors of longer survival. In comparison to no treatment, surgery alone was associated with significant improvement in survival [adjusted hazard ratio (adj HR) 0.64 (0.61–0.67)], but not radiation [adj HR 1.15 (1.08–1.23)]. Surgery and radiation combined had similar survival as surgery alone [adj HR 0.69 (0.64–0.76)]. Results were similar when cases diagnosed between 1973 and 1999 were compared to cases diagnosed between 2000 and 2009.

Conclusions

Despite developments in surgical and radiation techniques, the prognosis for MPM patients has not improved over the past 4 decades. Cancer-directed surgery is independently associated with better survival, suggesting that multimodal surgery-based therapy can benefit these patients. Further research in adjuvant treatment is necessary to improve prognosis in this challenging disease.     

Compartmentalization of the splicing machinery in plant cell nuclei

The cell nucleus is a membrane-surrounded organelle that contains numerous compartments in addition to chromatin. Compartmentalization of the nucleus is now accepted as an important feature for the organization of nuclear processes and for gene expression. Recent studies on nuclear organization of splicing factors in plant cells provide insights into the compartmentalization of the plant cell nuclei and conservation of nuclear compartments between plants and metazoans.