Role of AtPol ζ, AtRev1 and AtPolη in γ ray-induced mutagenesis

Although ionizing radiation has been employed as a mutagenic agent in plants, the molecular mechanism(s) of the mutagenesis is poorly understood. AtPolζ, AtRev1 and AtPolη are Arabidopsis translesion synthesis (TLS)-type polymerases involved in UV-induced mutagenesis. To investigate the role of TLS-type DNA polymerases in radiation-induced mutagenesis, we analyzed the mutation frequency in AtPolζ-, AtRev1- or AtPolη-knockout plants rev3-1, rev1-1 and polh-1, respectively. The change in mutation frequency in rev3-1 was negligible, whereas that in rev1-1 decreased markedly and that in polh-1 increased slightly compared to wild-type. Abasic (apurinic/apyrimidinic; AP) sites, induced by radiation or generated during DNA repair processes, can pair with any kind of nucleotide on the opposite strand. 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-oxo-dG), induced by radiation following formation of reactive oxygen species, can pair with cytosine or adenine. Therefore, AtRev1 possibly inserts dC opposite an AP site or 8-oxo-dG, which results in G to T transversions.Key words: ionizing radiation, DNA damage, translesion synthesis, ROS, 8-oxo-dG, ArabidopsisIonizing radiation has been applied to various plants for the purpose of generating useful agricultural resources. A variety of ionizing radiation forms, including X rays, γ rays, neutrons and ion-beams, have been used as mutagens for mutation breeding in addition to chemical mutagens.¹ Nevertheless, the molecular mechanism(s) associated with radiation-induced mutations in higher plants remains to be fully understood.In animals and microorganisms, it is known that a large proportion of mutations occur when damaged DNA is replicated by specific DNA polymerases. This activity is referred to as “translesion synthesis (TLS),” and represents one of the damage-tolerance pathways conserved from bacteria to humans. TLS-type polymerases have a more relaxed active site structure compared to replicases and therefore can act on damaged templates. However, the very flexible nature of the active site can induce high and sometimes fatal, replication errors. In higher plants, the presence of several TLS-type polymerase genes was reported. AtREV3 encodes the catalytic subunit of AtPolζ.² AtPOLK, AtREV1 and AtPOLH encode AtPolκ, AtRev1 and AtPolη, respectively.^3–7 In our previous paper, we suggested the role of three TLS-type polymerases, AtPolζ, AtRev1 and AtPolη, in the formation of UV-induced mutations.⁸Since the variety and ratio of UV-induced DNA damage have been well characterized, and the TLS activity of each polymerase can be examined in vitro, it is relatively easy to speculate on how the TLS polymerases induce mutation following UV-exposure. By contrast, ionizing radiation can induce a variety of damage, including damage to bases and strand breaks, and the role of TLS-type polymerases in radiation-induced mutation is less understood.In an effort to determine whether TLS polymerases are involved in radiation-induced mutation in higher plants, we analyzed the mutation frequency in Arabidopsis somatic tissues following γ ray irradiation. The reporter gene used for this analysis was the uidA_166G-T gene, which contains a nonsense mutation generated by replacement of the 166^th guanine with thymine.⁹ The reporter gene integrated in the Arabidopsis genome will become active when a T-to-G reversion occurs at the 166^ththymine. To detect γ ray-induced mutations, transgenic plants carrying the uidA_166G-T were treated with 100 Gy of γ rays and then grown for another 10 days, so that cells with an active uidA gene can proliferate and produce a detectable blue sector on somatic tissues.To investigate the roles of TLS-type polymerases in radiation-induced mutations, we examined the mutation frequencies in disruptants of the AtREV3, AtREV1 and AtPOLH genes, rev3-1, rev1-1 and polh-1, respectively, and compared these to that of wild-type. The reversion events in rev3-1 did not change significantly compared to wild-type siblings (Fig. 1). This is contrasted with the reduction in UV-induced mutation frequency when AtPolζ is disrupted.⁸ However, the reversion events in rev1-1 plants were less than 1/10 of that in wild-type siblings (p < 0.01). This result indicates that AtRev1 plays a role in promoting γ ray-induced mutations. The reversion event in polh-1 was slightly (∼1.4 times) higher than that in wild-type siblings (p < 0.05), suggesting that AtPolη plays a role in reducing γ ray-induced mutations.Open in a separate windowFigure 1γ ray-induced mutation frequencies in AtREV3-, AtREV1- and AtPOLH-disrupted plants. Wild-type and mutant derived from a single F1 plant were examined concurrently. Bars represent average frequencies per 100 plants derived from multiple experiments. error bars indicate ±SE. *p < 0.01; **p < 0.05.The frequencies in wild-type, rev3-1, rev1-1 and polh-1 were 12, 22, 1.9 and 13 times higher, respectively, with γ ray exposure compared to the spontaneous mutation frequency as previously reported.⁸ These results indicate that the G to T transversion was greatly induced by γ ray exposure.Since ionizing radiation can induce a variety of damage to DNA or nucleotide pools, the mechanisms associated with radiation-induced mutagenesis would be more complicated than those pertaining to UV-induced mutagenesis. It is known that some kinds of damage are more abundantly generated by ionizing radiation. Additionally, some kinds of damage are preferentially used as templates or substrates by specific DNA polymerases. Based on previous reports relating to plants or other organisms, we propose two possible mechanisms to account for the γ ray-induced reversion events (Fig. 2).Open in a separate windowFigure 2Possible role of TLS polymerases in γ ray-induced mutagenesis. (A) role of TLS polymerases in the replication of AP sites. Ionizing radiation induces formation of an AP site (O). AtRev1 inserts dC opposite the AP site, leading to a G to T transversion. AtPolη inserts dA or T opposite the AP site, contributing less to G to T transversions. (B) Ionizing radiation induces the formation of reactive oxygen species (ROS) which oxidize guanine (G) in DNA or dGTP, producing 8-oxo-dG or 8-oxo-dGTP (G^o). 8-oxo-dGTP is misincorporated opposite adenine (A) through replication. G^o is paired with cytosine (C) at the next round of DNA replication, which results in a T to G transversion. AtPolη inserts dC or dA opposite G^o, whereas AtRev1 inserts dC opposite G^o. Other polymerases including AtPolκ might insert dA opposite G^o.Abasic (apurinic/apyrimidinic; AP) sites represent one of the most abundant DNA lesions that occur spontaneously and are induced by radiation.¹⁰ AP sites can also be generated during the DNA repair process.¹¹ If the 166^th T of our marker gene were lost following irradiation with γ rays, the template would induce various mutations.Among the TLS-type polymerases, Rev1s share the specific ability to insert dCMP opposite AP sites.^12–14 Therefore, the significant reduction in mutation frequency in AtRev1-knockout plants might be due to loss of dCMP insertion opposite AP sites (Fig. 2A). In contrast, it was shown that yeast or human Polηs insert dA or T opposite AP sites or AP-site analogs.^15–17 Thus, the activity of Polη does not seem to contribute toward T to G transversions (Fig. 2A). The incidence of mutagenic bypass of AP sites by AtRev1 may be greater when AtPolη is absent, which elevates the mutation frequency slightly.Given the similar reduction in UV-induced mutation frequencies, we previously suggested that AtRev1 cooperates with AtPolζ to bypass UV-damage.⁸ In contrast, no significant change in γ ray-induced mutation frequency was observed in AtPolζ-knockout plants. This suggests that AtRev1 might work independently of AtPolζ when bypassing AP sites, although it is not consistent with previous reports concerning yeast.^15,16Radiation damages cells through the formation of reactive oxygen species (ROS). ROS induce oxidative damage of DNA, including strand breaks and base and nucleotide modifications. The formation of 7,8-dihydro-8-oxo-2′-deoxy-guanosine (8-oxo-dG) represents one of the most abundant and best characterized type of oxidative damage.¹⁸ 8-oxo-dG can pair with cytosine or adenine, inducing frequent base substitutions. In addition to direct oxidation of deoxyguanosine (dG) in DNA, 8-oxo-dG can be generated by the incorporation of oxidized dGTP (8-oxo-dGTP) into DNA during the replication process.¹⁹ 8-oxo-dG in DNA induces mutations when used as a template for the next round of replication. If 8-oxo-dGTP were incorporated in lieu of the 166^thT and paired with dC in the next round of replication, it would lead to a T to G transversion (Fig. 2B).It was shown that yeast and human Rev1s insert dC at positions opposite 8-oxo-dG.^13,20 Therefore, the reduction in mutation frequency in AtRev1-knockout plants could be due to loss of dCMP insertion opposite 8-oxo-dG (Fig. 2B). Although human and yeast Polηs can insert dC or dA opposite 8-oxo-dG, the insertion efficiencies and dC/dA ratios differ depending on the assay conditions and sequence context.^21–25 Thus, the balance of error-free and error-prone bypass activities of Polη might interfere with the mutation frequency in individual assays. The slight increase in mutation frequency in AtPolη-knockout plants suggests that the ratio of dC insertion by other polymerases was slightly higher when AtPolη is absent.In yeast, spontaneous mutations in base excision repair (BER)-deficient cells are not reduced by elimination of Polζ, suggesting a minor role of Polζ in 8-oxo-dG induced mutations.^26,27 Our result demonstrating no reduction in mutation frequency in AtPolζ-knockout plants suggests that AtPolζ is also dispensable in terms of 8-oxo-dG induced mutagenesis. However, the root growth of AtPolζ-knockout plants is severely inhibited by γ ray exposure.^2,4 Therefore, it is possible that AtPolζ has other function(s) in radiation-induced damage responses.In addition to the three polymerases examined in this report, Arabidopsis possesses an additional TLS-type polymerase referred to as AtPolκ. In vitro analysis revealed that AtPolκ preferentially inserts dA opposite 8-oxo-dG,²⁸ as is the case with human Polκ.^29,30 Therefore, it is conceivable that AtPolκ has a function to promote T to G transversions (Fig. 2B). It will be interesting to measure the mutation frequency in AtPolκ-knockout plants following γ ray exposure. Further, analyses of mutation frequencies in BER- or mismatch repair (MMR)-deficient mutants will be necessary to delineate the mechanism(s) of radiation-induced mutagenesis in higher plants.     

Trends in Cancer Incidence in Maputo,Mozambique, 1991–2008

Background

Very limited information is available regarding the incidence of cancer in sub-Saharan Africa. We analyzed changes in cancer patterns from 1991 to 2008 in Maputo (Mozambique).

Methods

We calculated the rates of incidence of different cancer sites by sex in the 5-year age-group of the population of Maputo city as well as age-standardized rates (ASRs) and average annual percentage changes (AAPC).

Results

Over the 18-year study period a total of 12,674 cases of cancer (56.9% females) were registered with an overall increase in the risk of cancer in both sexes. In males, the most common cancers were those of the prostate, Kaposi sarcoma (KS) and the liver. Prostate cancer showed the most dramatic increase over the whole study period (AAPC +11.3%; 95% CI: 9.7–13.0), with an ASR of 61.7 per 10⁵ in 2003–2008. In females, the most frequent cancers were of the uterine cervix, the breast and KS, with the former increasing along the whole study period (AAPC + 4.7%; 95% CI: 3.4–6) with an ASR of 62.0 per 10⁵ in 2003–2008 as well as breast cancer (AAPC +6.5%; 95%CI: 4.3–8.7).

Conclusions

Overall, the risk of cancer rose in both sexes during the study period, particularly among cancers associated with westernization of lifestyles (prostate, breast), combined with increasingly rising incidences or limited changes in cancers associated with infection and poverty (uterine cervix, liver). Moreover, the burden of AIDS-associated cancers has shown a marked increase.     

Trends in socioeconomic inequalities in cervical,breast, and colorectal cancer screening participation among women in Japan, 2010–2019

BackgroundIt is known that socioeconomic status (SES) influences the outcome of cancer treatment and this could partly be explained by decreased use of cancer screening services by people of lower SES. Many studies have indicated that low SES, including low educational attainment or unstable employment, was related to nonparticipation in cancer screening. However, studies investigating trends in SES inequalities within cancer screening participation are limited. Our objective was to examine trends in SES inequalities in cervical, breast, and colorectal cancer screening participation among women in Japan between 2010 and 2019.MethodsWe analyzed 189,442, 168,571, 163,341, and 150,828 women in 2010, 2013, 2016, and 2019 respectively, using nationally representative cross-sectional surveys. The main outcome variables are participation in each cancer screening. We used educational attainment and employment status as measures for SES. Multivariable logistic regression analysis, adjusted for age, marital status, educational attainment, and employment status was performed to evaluate the associations between SES and nonparticipation in each cancer screening.ResultsOverall participation rates in each cancer screening increased between 2010 and 2019. Low educational attainment and non-permanent employment status were related to nonparticipation in each cancer screening and inequality according to employment status increased within each screening participation during the study period. For example, dispatched workers were more likely to not participate in cervical cancer screening than permanent workers: in 2010, [aOR 1.11 95 %CI: 1.01 –1.21], and in 2019, [aOR 1.46 95 %CI: 1.34–1.60]. The inequality was greatest in colorectal cancer screening nonparticipation, followed by breast and cervical screening.ConclusionsAlthough the participation rates in each cancer screening have increased, inequality in participation in terms of employment status widened among women in Japan between 2010 and 2019. Reducing inequalities in cancer screening participation is essential for cancer screening intervention policies.     

Allometry of aboveground biomasses in mangrove species in Itamaracá, Pernambuco, Brazil

Allometric equations to estimate aboveground biomass (AGB) and plant part biomasses (PPB) of three mangrove species, Rhizophora mangle, Avicennia schaueriana, and Laguncularia racemosa, were determined in Itamaracá, Pernambuco, Brazil (7°48′44″S and 34°49′39″W). Twenty-three to thirty-six trees of each species, ranging in height (H) from 1.6 to 11.8 m and in diameter, at breast height or above prop roots (D), from 2 to 21 cm, were measured, cut, and separated into stems, branches, leaves, and prop roots. Biomass proportions in each tree part were similar among species, excluding prop roots: stems 37–47%, branches 41–46%, and leaves 11–17%. Prop roots represented 37% of AGB in R. mangle. Tree size had a significant but not large influence on biomass distribution among plant parts: as stem diameters increased the proportions allocated to leaves decreased and those to stems and branches increased. AGB and PPB were significantly related to D and D² × H and the best fittings were obtained with power equations. A few equations from literature fitted the data reasonably well for AGB of one or two of the species but resulted in large errors for the others. Applying the equations to previous measurements of tree diameters in a sample area, AGB for the mangrove site was estimated at 105 Mg ha⁻¹, with 78, 19, and 3% corresponding to biomasses of R. mangle, L. racemosa, and A. schaeuriana trees, respectively.     

Children's participation in healthcare in the UK--gesture,rhetoric, or real involvement?

In the United Kingdom (England, Wales, Scotland, and Northern Ireland) children and their best interests are protected through a range of best practice initiatives, and legislation and guidance at country, national, European, and global levels. Some of the recent commitment by the government may be the result of enlightened thinking, but some of it has resulted from the aftermath of at least two major healthcare incidents. This article reviews the UK's recent national and international efforts to protect its thirteen million children and ensure that their voices are heard.     

Tumor necrosis factor-α in macrophages of heart,liver, kidney,and in the pituitary gland

The relationship between myonuclear number, cellular size, succinate dehydrogenase activity, and myosin type was examined in single fiber segments (n=54; 9±3 mm long) mechanically dissected from soleus and plantaris muscles of adult rats. One end of each fiber segment was stained for DNA before quantitative photometric analysis of succinate dehydrogenase activity; the other end was double immunolabelled with fast and slow myosin heavy chain monoclonal antibodies. Mean±S.D. cytoplasmic volume/myonucleus ratio was higher in fast and slow plantaris fibers (112±69 vs. 34±21x10³ m³) than fast and slow soleus fibers (40±20 vs. 30±14x10³ m³), respectively. Slow fibers always had small volumes/myonucleus, regardless of fiber diameter, succinate dehydrogenase activity, or muscle of origin. In contrast, smaller diameter (<70 m) fast soleus and plantaris fibers with high succinate dehydrogenase activity appeared to have low volumes/myonucleus while larger diameter (>70 m) fast fibers with low succinate dehydrogenase activity always had large volume/myonucleus. Slow soleus fibers had significantly greater numbers of myonuclei/mm than did either fast soleus or fast plantaris fibers (116±51 vs. 55±22 and 44±23), respectively. These data suggest that the myonuclear domain is more limited in slow than fast fibers and in the fibers with a high, compared to a low, oxidative metabolic capability.     

Trends in schistosomiasis-related mortality in Brazil, 2000–2011

Schistosomiasis is an important public health problem, with high morbidity and mortality in endemic countries. We analysed the epidemiological characteristics and time trends of schistosomiasis-related mortality in Brazil. We performed a nationwide study based on official mortality data obtained from the Brazilian Mortality Information System. We included all deaths in Brazil between 2000 and 2011, in which schistosomiasis was mentioned on the death certificate as an underlying or associated cause of death (multiple causes of death). We calculated crude and age-adjusted mortality rates (per 100,000 inhabitants), and proportional mortality rates. Trends over time were assessed using joinpoint regression models. Over the 12-year study period, 12,491,280 deaths were recorded in Brazil. Schistosomiasis was mentioned in 8,756 deaths, including in 6,319 (72.2%) as an underlying cause and in 2,437 (27.8%) as an associated cause. The average annual age-adjusted mortality rate was 0.49 deaths/100,000 inhabitants (95% confidence interval: 0.46–0.52) and proportional mortality rate was 0.070% (95% confidence interval: 0.069–0.072). Males (0.53 deaths/100,000 inhabitants), those aged ⩾70 years (3.41 deaths/100,000 inhabitants), those of brown race/colour (0.44 deaths/100,000 inhabitants), and residents in the Northeast region of Brazil (1.19 deaths/100,000 inhabitants) had the highest schistosomiasis-related death rates. Age-adjusted mortality rates showed a significant decrease at a national level (Annual Percent Change: −2.8%; 95% confidence interval: −4.2 to −2.4) during the studied period. We observed decreasing mortality rates in the Northeast (Annual Percent Change: −2.5%; 95% confidence interval: −4.2 to −0.8), Southeast (Annual Percent Change: −2.2%; 95% confidence interval: −3.6 to −0.9), and Central-West (Annual Percent Change: −7.9%; 95% confidence interval: −11.3 to −4.3) regions, while the rates remained stable in the North and South regions. Despite the reduced mortality, schistosomiasis is still a neglected cause of death in Brazil, with considerable regional differences. Sustainable control measures should focus on increased coverage, and intensified and tailored control measures, to prevent the occurrence of severe forms of schistosomiasis and associated deaths.     

Influenza in Outpatient ILI Case-Patients in National Hospital-Based Surveillance,Bangladesh, 2007–2008

Background

Recent population-based estimates in a Dhaka low-income community suggest that influenza was prevalent among children. To explore the epidemiology and seasonality of influenza throughout the country and among all age groups, we established nationally representative hospital-based surveillance necessary to guide influenza prevention and control efforts.

Methodolgy/Principal Findings

We conducted influenza-like illness and severe acute respiratory illness sentinel surveillance in 12 hospitals across Bangladesh during May 2007–December 2008. We collected specimens from 3,699 patients, 385 (10%) which were influenza positive by real time RT-PCR. Among the sample-positive patients, 192 (51%) were type A and 188 (49%) were type B. Hemagglutinin subtyping of type A viruses detected 137 (71%) A/H1 and 55 (29%) A/H3, but no A/H5 or other novel influenza strains. The frequency of influenza cases was highest among children aged under 5 years (44%), while the proportions of laboratory confirmed cases was highest among participants aged 11–15 (18%). We applied kriging, a geo-statistical technique, to explore the spatial and temporal spread of influenza and found that, during 2008, influenza was first identified in large port cities and then gradually spread to other parts of the country. We identified a distinct influenza peak during the rainy season (May–September).

Conclusions/Significance

Our surveillance data confirms that influenza is prevalent throughout Bangladesh, affecting a wide range of ages and causing considerable morbidity and hospital care. A unimodal influenza seasonality may allow Bangladesh to time annual influenza prevention messages and vaccination campaigns to reduce the national influenza burden. To scale-up such national interventions, we need to quantify the national rates of influenza and the economic burden associated with this disease through further studies.     

Isonymous structure in the white population of Córdoba, Argentina, in 1813

Surnames analysis is useful for populations in which only written documents remain, as is the case for historical populations. In Córdoba province, Argentina, census records contain nominal data of inhabitants, including information on sex, age, ethnosocial category, civil status, occupation, place of birth, and residence, that can be analyzed using surnames. Relationship indicators within and among ecclesiastic units in Córdoba were estimated by isonymy for the adult white population registered in the 1813 census. The Rii, Rij, and R(ST) coefficients and the surname abundance indicator (a) were calculated. Lasker's distances among categories of population units were used to cluster the 16 provincial population categories. Gradients for kinship within population and for surname diversity were in agreement with the principal areas and waves of original settlement in the province. The main population clusters reflect those areas, whereas minor clusters coincide with the network of roads existing in the territory by 1813. The structure of the white population in Córdoba province was determined by the geographic location of the original waves of settlement, and it followed a pattern of relationships conditioned by the routes connecting population units in the Colonial period.     

Theanine, γ-glutamylethylamide,a unique amino acid in tea leaves,modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats

Theanine (γ-glutamylethylamide) is one of the major amino acid components in green tea and can pass through the blood-brain barrier. Recent studies suggest that theanine affects the mammalian central nervous system; however, the detailed mechanism remains unclear. In this study, we demonstrated the effect of theanine on neurotransmission in the brain striatum by in vivo brain microdialysis. Theanine injection into the rat brain striatum did not increase the concentration of excitatory neurotransmitters in the perfusate. On the other hand, theanine injection increased the concentration of glycine in the perfusate. Because it has been reported that theanine promotes dopamine release in the rat striatum, we investigated the glycine and dopamine concentrations in the perfusate. Co-injection of glycine receptor antagonist, strychnine, reduced theanine-induced changes in dopamine. Moreover, AMPA receptor antagonist, which regulates glycine and GABA release from glia cells, inhibited these effects of theanine and this result was in agreement with the known inhibitory effect of theanine at AMPA receptors.     

Parental Monitoring,Parent-Adolescent Communication,and Adolescents’ Trust in Their Parents in China

Purpose

Trust is an important aspect of interpersonal relationships, but little is known about adolescents’ interpersonal trust. The aim of the present study was to examine the associations among parental monitoring, parent-adolescent communication, and adolescents’ trust in their parents in China.

Methods

Data in this study were collected as part of the cross-sectional study of children in China. 3349 adolescents (female 48.6%, age range of 12–15 years) were randomly selected from 35 secondary schools in April, 2009 and administered to the Adolescent Interpersonal Trust Scale, the Parental Monitoring Scale, and the Parent-Adolescent Communication Scale.

Results

Adolescents’ trust in their parents was positively related to parental monitoring and parent-adolescent communication. Furthermore, parent-adolescent communication mediated the association between parental monitoring and adolescents’ trust in their parents. The mediation model fit data of both genders and three age groups equally well.

Conclusions

Parental monitoring and parent-adolescent communication play an importance role in fostering adolescents’ trust in their parents.     

Leishmania infection in humans, dogs and sandflies in a visceral leishmaniasis endemic area in Maranhão, Brazil

Leishmania infection in humans, dogs and sandflies was examined in the endemic visceral leishmaniasis (VL) municipality of Raposa, state of Maranh?o, Brazil. In this study, we examined Leishmania chagasi infection in the blood serum of both humans and Canis familiaris and the natural Leishmania sp. infection rate in the sandfly vector, Lutzomyia longipalpis. Enzyme-linked immunosorbent assay, indirect immunofluorescence reaction and polymerase chain reaction were performed to detect Leishmania infections in humans, dogs and sandflies, respectively. Overall, 186 out of 986 studied human beings were infected with L. chagasi parasites, representing an infection prevalence of 18.9%. An even higher infection rate was detected in dogs, where 66 (47.8%) out of 138 were infected. Among all Lu. longipalpis captured (n = 1,881), only 26.7% were females. The Leishmania infection frequency for the vector Lu. longipalpis was 1.56%. Remarkably, all infected sandflies were found in the peridomiciliary area. Furthermore, a high incidence of asymptomatic forms of VL in the human and canine populations was observed. The results of this study suggest autochthonous transmission of L. chagasi in this endemic area for visceral leishmaniasis because infection by Leishmania sp. was identified in all important elements of the transmission chain.     

Mating types in yeast,vomeronasal organ in rodents,homosexuality in humans: does a guiding thread exist?

Pheromones and their receptors are the molecules used by very different organisms in order to join two haploid cells. It happens evidently in yeast, since the two blending haploid cells are also the two mating organisms, whereas in rodents pheromone receptors are the triggers of the vomeronasal system which, supervising sexual behaviors, is responsible for copulation and therefore for fertilization. The debate is still open about the real significance of pheromones in humans but a working vomeronasal organ, able to recognize pheromones of the same sex, could be the simplest biological explanation of homosexuality. This hypothesis is discussed and connected with some well known experimental data.     

Interindividual human variation in cisplatinum sensitivity, predictable in an in vitro assay?

Cisplatinum [cis-diamminedichloroplatinum(II)] is one of the most active antitumour agents and its effect is mainly due to the formation of cisplatinum-DNA crosslinks. Formation of cisplatinum-DNA intrastrand crosslinks in nucleated white blood cells of patients was measured, both in (pretreatment) samples exposed in vitro and in cells collected immediately after in vivo exposure to cisplatinum. Large interpatient variations were found. The in vitro results showed a linear correlation with the in vivo data (cc = 0.91). The in vitro measurements of crosslinks may allow prediction of response and avoidance of toxicity in individual patients.     

Trends in antibiotic resistance in Prevotella species from patients of the University Hospital of Maxillofacial Surgery,Sofia, Bulgaria,in 2003–2009

Head-and-neck infections often involve anaerobes such as Prevotella species. Aim of the present study was to assess the evolution and the factors associated with resistance in Prevotella species to penicillin, clindamycin, metronidazole, tetracycline and β-lactams/β-lactamase inhibitors (BL/BLIs). In total, 192 Prevotella strains, isolated from patients with oral and head-and-neck infections, were evaluated. Common isolates were Prevotella intermedia and Prevotella melaninogenica within the pigmented species as well as Prevotella oris and Prevotella oralis group within the non-pigmented species. Overall resistance was 43.2% for penicillin, 10.9% for clindamycin, 0% for metronidazole. Nonsusceptibility to tetracycline was 29.1% without significant differences in resistance rates between pigmented and other species. Penicillin resistant strains were β-lactamase positive. From 2003–2004 to 2007–2009, penicillin resistance rates increased about four-fold (from 15.4% to 60.6%). Clindamycin resistance did not show evolution, whereas tetracycline nonsusceptibility decreased from 43.3% in 2003–2004 to 20.7% in 2007–2009. Except for one (0.5%) P. oralis strain with intermediate susceptibility to BL/BLIs, the other strains were susceptible to the agents. In conclusion, in Prevotella strains from patients with head-and-neck infections, the resistance rate to penicillin increased, that to clindamycin remained stable and the nonsusceptibility rate to tetracycline decreased during the period. Activity against >99% of Prevotella strains was observed with metronidazole and BL/BLIs. The penicillin resistance and tetracycline nonsusceptibility were associated with the year of study, national antibiotic consumption and possibly with previous treatment (for tetracycline). The evolution of penicillin resistance in Prevotella strains was highly dynamic.     

Changes in FADD levels,distribution, and phosphorylation in TNFα-induced apoptosis in hepatocytes is caspase-3, caspase-8 and BID dependent

FADD/MORT1 (The adaptor protein of Fas Associate Death Domain/Mediator of Receptor Induced Toxicity) is essential for signal transduction of death receptor signaling. We have previously shown that FADD is significantly up-regulated in TNFα/ActD induced apoptosis. Over-expression of FADD also induces death of lung cancer cells and primary hepatocytes. We hypothesize that the increase in detectable FADD levels require the proximal steps in apoptotic signaling and speculated that FADD would be redistributed in cells destined to undergo apoptosis. We show that monomeric non-phosphorylated FADD is up-regulated in hepatocytes treated with TNFα/ActD and that it accumulates in the cytoplasm. Nuclear phosphorylated FADD decreases with TNFα/ActD treatment. Dimeric FADD in the cytoplasm remains constant with TNFα/ActD. The change in FADD levels and distribution was dependent on caspase-3, caspase-8 activity and the presence of BID. Thus, changes in FADD levels and distribution are downstream of caspase activation and mitochondria changes that are initiated by the formation of the DISC complex. Changes in FADD levels and distribution may represent a novel feed-forward mechanism to propagate apoptosis signaling in hepatocytes. Xiaoying Zhang and Raghuveer Vallabhaneni contributed equally to the work.