Intermediate Proportion Research Articles

Impact of pest control strategies on the arthropodofauna living in bird nests built in nestboxes in pear and apple orchards

Pesticide applications have a strong impact on biodiversity in agroecosystems. The present study aimed to assess the impact of pest control strategies on the arthropodofauna of Parus major nests built within nestboxes installed in orchards. Unlike many studied groups, these arthropod communities are not in direct contact with pesticide sprays (on account of their being sheltered by nestboxes) and are also unable to move away from the treated area. In this pilot study, we estimated the prevalence and the taxonomic and ecological diversities of arthropodofauna sampled in the nests and assessed the extent to which the whole and nest-specific arthropodofauna were affected by pest control strategies. Sixteen different insect and arachnid Primary Taxonomic Groups (PTGs, order level or below) were found in nests. The best represented PTGs (≥10% occurrence in years 2007 and 2008) were Psocoptera (Insecta, detritivorous/saprophagous), detritivorous/saprophagous Astigmata (Acari) and hematophagous Mesostigmata (Acari). Pest control strategies had a large impact on the prevalence of arthropods in nests, with higher proportions of nests hosting arthropods in organic orchards than in conventional orchards and with intermediate proportions in nests in Integrated Pest Management orchards. In contrast, pest control strategies had no significant effect on the composition of the arthropod communities when only nests hosting nidicolous arthropods were considered.

Effect of copper loadings on product selectivities in microwave-enhanced degradation of phenol on alumina-supported copper oxides

Alumina-supported copper oxides catalysts were prepared using impregnation method and characterized using XRD, SEM and BET. Catalytic activities in phenol removal from its aqueous solution (200ppm) were studied using hydrogen peroxide as an oxidant under microwave irradiation. Effects of copper loadings, reaction temperatures (50 and 70°C) and pH (5 and 9) were studied. The high loading samples (9–14wt%) exhibited 97% phenol removal efficiency corresponding to 90% total organic carbon (TOC) value. Lower loading samples (1wt%) showed significantly lower phenol removals and inferior catalyst stability. At similar levels of phenol degradations, there was higher proportion of high molecular weight products or intermediates on 14 than on 1wt% copper/Al2O3.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

The Antibiotic Susceptibility Patterns of Uropathogenic Escherichia Coli , With Special Reference to the Fluoroquinolones

The emergence of drug resistance to trimethoprim-sulfamethoxazole, the penicillins, cephalosporins, and fluoroquinolones by Uropathogenic Escherichia coli (UPEC) has limited the options for selecting the appropriate antibiotic for the treatment of urinary tract infections. The The E. coli isolates, which were obtained from the culture of urine samples,were studied for their antibiotic resistance patterns, with special reference to the antimicrobial activity of the fluoroquinolones and the production of the extended spectrum β-lactamases. (ESBL), Settings and Design: This was a hospital based, prospective study which was done for a period of eighteen months. This study was done by using the standard culture techniques for urine samples, the modified Kirby-Bauer disk diffusion method for the antibiotic susceptibility testing and the disk diffusion method to confirm the ESBL production by the clinical isolates of E. coli in urine. The sensitivity pattern was correlated with the clinical condition and the presence of the risk factors. The statistical analysis which was used: The statistical analysis was done by using the proportions of sensitive, resistant and intermediates. Descriptive statistics like the total, mean and percentage were done by using the Statistical Package for the Social Sciences (SPSS), version 15.0. The hospital isolates showed high degrees of resistance to the penicillins, cephalosporins, nalidixic acid and the fluoroquinolones, with 59% of the isolates being ESBL producers. The incidence of the multidrug resistant strains of Escherichia coli has been steadily increasing over the past few years. The knowledge on the resistance pattern of the bacterial strains in a geographical area will help in guiding the appropriate and the judicious use of antibiotics. Also, the formulation of an appropriate hospital antibiotic policy will go a long way in controlling these infections.

Intertidal Food Webs in Rocky Shores: Topology and Energetics

The study of food webs is a very important topic in order to understand the dynamics and stability of communities. We studied the food webs structure and energy balance of some tide pools from a rocky shore of Mar del Plata (Argentina). Food webs were drawn, and connectivity, proportion of different trophic species, and the link-richness regression slope were determined. Photosynthesis and respiration rates of several species were also measured. All the topological measures were calculated with and without sediments/detritus as potential energy sources. The proportion of basal species and the connectivity were greater when detritus were included; proportion of intermediate species lowed significantly with detritus inclusion. There were no differences between seasons, but sampling sites did show differences. Proportion of top species and connectivity did not show differences in any case. Some discrepancies were found with respect to the theoretical expected values of the food web properties: the proportion of basal species was significantly higher and the intermediate species proportion significantly smaller than the theoretical ones. Slope of the L-S regression was near 2 and the fit was improved when detritus was included. Mesograzers showed higher respiratory rates in spring and green algae higher photosynthetic rates in autumn. Considering the entire intertidal zone, anemone and mussels were the most important oxygen consumers. The intertidal zone works as a source of production with P/R ratio greater than one.

Mixture design applied for the study of the tartaric acid effect on starch/polyester films

Tartaric acid (TA), a dicarboxylic acid, can act as a compatibiliser in starch/polyester blends. A mixture design was proposed to evaluate the effect of TA on the properties of starch/poly (butylene adipate co-terephthalate) (PBAT) blown films plasticised with glycerol. The interaction between the starch/PBAT and the TA has a positive effect on the tensile strength and puncture force. Additionally, greater proportions of TA increased Young's modulus. The starch+PBAT/TA and Gly/TA interactions contributed to a reduction in the water vapour permeability of the films. The inclusion of TA did not change the crystallinity of the samples. Formulations with intermediate proportions of TA (0.8g/100g) were shown to produce the best compatibilising effect. This was observed by DMA analysis as a consequence of the perfect equilibrium between the contributions of TA as a compatibiliser and in the acidolysis of starch, resulting in films with a tensile strength of 5.93MPa, a possible alternative to non-biodegradable packaging.

Critical points in logistic growth curves and treatment comparisons

Several biological phenomena have a behavior over time mathematically characterized by a strong increasing function in the early stages of development, then by a less pronounced growth, sometimes showing stability. The separation between these phases is very important to the researcher, since the maintenance of a less productive phase results in uneconomical activity. In this report we present methods of determining critical points in logistic functions that separate the early stages of growth from the asymptotic phase, with the aim of establishing a stopping critical point in the growth and on this basis determine differences in treatments. The logistic growth model is fitted to experimental data of imbibition of araribá seeds (Centrolobium tomentosum). To determine stopping critical points the following methods were used: i) accelerating growth function, ii) tangent at the inflection point, iii) segmented regression; iv) modified segmented regression; v) non-significant difference; and vi) non-significant difference by simulation. The analysis of variance of the abscissas and ordinates of the breakpoints was performed with the objective of comparing treatments and methods used to determine the critical points. The methods of segmented regression and of the tangent at the inflection point lead to early stopping points, in comparison with other methods, with proportions ordinate/asymptote lower than 0.90. The non-significant difference method by simulation had higher values of abscissas for stopping point, with an average proportion ordinate/asymptote equal to 0.986. An intermediate proportion of 0.908 was observed for the acceleration function method.

Diurnal variation in fatty acid profiles in rumen digesta from dairy cows grazing high-quality pasture

Six dairy cows receiving a once-daily high-quality pasture allocation in the afternoon were used to investigate the relationship between diurnal variation in rumen fermentation activity and diurnal variation in rumen fatty acids (FA). Rumen digesta was collected every two hours over a 24h period, and rumen pH, volatile fatty acid (VFA) concentration and FA were measured. Cows receiving a once-daily pasture allocation in the afternoon had lower rumen pH at night than during the day, while the variation pattern of VFA concentration and rumen pH was exaggerated, but broadly similar, to previous reports of cows on once daily pasture allocation. Rumen FA profiles varied considerably over the grazing cycle, with the most dramatic changes occurred in the evening and overnight, especially for odd- and branched-chain fatty acids (OBCFA) and C18 FA. Diurnal variation in OBCFA clearly reflected the microbial colonization of the newly ingested pasture while the variation in C18 FA was consistent with known biohydrogenation reactions in the rumen. Disappearances of most C18:3 n-3 and C18:2 n-6 by 8–12h after ingestion suggests a rapid biohydrogenation of plant-derived polyunsaturated fatty acids (PUFA), while the high proportions of unsaturated C18 intermediates (especially C18:2 t11, c15 and C18:1 t11) and low proportion of C18:0 measured in the present study suggests inhibition of the final step of biohydrogenation by the high level of C18:3 n-3. The low proportion of conjugated linoleic acid (CLA c9, t11) in rumen digesta confirms an endogenous synthesis of this CLA isomer in milk fat of pasture based cows. The principal component analysis (PCA) biplot analysis provides a good description of variation in the overall FA, as well as the main biohydrogenation pathway for C18:3 n-3. The lower rumen buffering capacity (decreased rumen pH), dramatic decline in rumen microbial population (assessed by total OBCFA) observed between 18:00 and 20:00, as well as the large increase in plant-derived PUFA implied a reduced rumen biohydrogenation activity during the evening, which might provide an approach to reduce the biohydrogenation of protected PUFA supplements by strategic feeding to coincide with reduced rumen activity.

Supplementation of increasing amounts of linseed oil to dairy cows fed total mixed rations: Effects on digestion, ruminal fermentation characteristics, protozoal populations, and milk fatty acid composition

The effect of linseed oil (LO) supplementation on nutrient digestibility, forage (i.e., timothy hay) in sacco ruminal degradation, ruminal fermentation characteristics, protozoal populations, milk production, and milk fatty acid (FA) profile in dairy cows was investigated. Four ruminally cannulated, primiparous lactating cows were used in a 4×4 Latin square design (28-d periods). They were fed a total mixed ration (50:50 forage:concentrate (F:C) ratio [dry matter (DM) basis] without supplementation (control, CTL), or supplemented (wt/wt; DM basis) with LO at 2, 3, or 4%. Supplementation with LO had no effect on DM intake (19kg/d) and apparent total-tract digestibility of nutrients (organic matter, neutral detergent fiber, acid detergent fiber, starch, and gross energy). Ruminal pH, ammonia, and total volatile FA concentrations were not changed by LO supplementation to diets. Extent of changes in volatile FA pattern and effective ruminal degradability of DM of timothy hay were minor. Neither the total numbers nor the genera distribution of protozoa was changed by the addition of increasing amounts of LO to the diet. Milk yield increased linearly (26.1, 27.3, 27.4, and 28.4kg/d for CTL to LO4, respectively) as the amount of LO added to the diet increased. Milk fat content was not affected by LO supplementation, whereas milk protein content decreased linearly with increasing amounts of LO in the diet. Milk fat proportions of several intermediates of ruminal biohydrogenation of polyunsaturated FA (i.e., trans-10 18:1, trans-11 18:1, cis-9,trans-11 18:2, trans-11,cis-15 18:2, and cis-9,trans-11,cis-15 18:3) increased linearly with LO addition to the diet. The proportion of cis-9,cis-12 18:2 decreased linearly (2.06, 1.99, 1.91, and 1.83% for CTL to LO4, respectively) as the amount of LO in the diet increased. Milk fat content of cis-9,cis-12,cis-15 18:3 increased as the level of LO in the diet increased up to 3% but no further increase was observed when 4% of LO was fed (0.33, 0.79, 0.86, and 0.86% for CTL to LO4, respectively). A similar quadratic response to LO supplementation was also observed for cis-5,cis-8,cis-11,cis-14,cis-17 20:5 and cis-5,cis-7,cis-10,cis-13,cis-16 22:5. The results of the present study show that LO can be safely supplemented up to 4% in forage-based diets of dairy cows to enrich milk with potential health beneficial FA (i.e., n-3 FA) without causing any detrimental effects on rumen function, digestion, and milk production.

Effects of stand structure on wind speed reduction in a Metasequoia glyptostroboides shelterbelt

In a Metasequoia glyptostroboides coastal forest shelterbelt near Shanghai, China, we studied relationships between stand structure and wind shelter effect. We located 16 plots at intervals of 500 m along the shelterbelt and characterized both horizontal and vertical structure of each plot. Wind speed was measured within each plot and at different distances windward and leeward. We found that wind shelter effects were closely related to stand structure of the studied M. glyptostroboides shelterbelt. Stands with high basal area but intermediate crown index and intermediate proportion of large trees (LT) produced the best shelter effects, with significantly longer shelter distance (d70, shelter distance which the wind speed U does not exceed 70 % of U0) and slightly lower minimum relative wind speed (Um/U0). Simple structural indices that can be easily measured in the field were good predictors of the shelter effect. LT was the best predictor of d70, while basal area at ground level was the best predictor of Um/U0. The relationships between stand structure and shelter effect provides a practical guideline to the design, construction and management of forest shelterbelts. In order to provide the best shelter effects, high basal area of >50 m2 ha−1 at ground level or >33 m2 ha−1 at breast height coupled with an intermediate LT value of about 60 % should be maintained for the studied M. glyptostroboides shelterbelt.

Effects of feeding different linseed sources on omasal fatty acid flows and fatty acid profiles of plasma and milk fat in lactating dairy cows

The aim of this experiment was to study the effects of feeding different linseed sources on omasal fatty acid (FA) flows, and plasma and milk FA profiles in dairy cows. Four ruminally cannulated lactating Holstein-Friesian cows were assigned to 4 dietary treatments in a 4×4 Latin square design. Dietary treatments consisted of supplementing crushed linseed (CL), extruded whole linseed (EL), formaldehyde-treated linseed oil (FL) and linseed oil in combination with marine algae rich in docosahexaenoic acid (DL). Each period in the Latin square design lasted 21 d, with the first 16 d for adaptation. Omasal flow was estimated by the omasal sampling technique using Cr-EDTA, Yb-acetate, and acid detergent lignin as digesta flow markers. The average DM intake was 20.6±2.5kg/d, C18:3n-3 intake was 341±51g/d, and milk yield was 32.0±4.6kg/d. Milk fat yield was lower for the DL treatment (0.96kg/d) compared with the other linseed treatments (CL, 1.36kg/d; EL, 1.49kg/d; FL, 1.54kg/d). Omasal flow of C18:3n-3 was higher and C18:3n-3 biohydrogenation was lower for the EL treatment (33.8g/d; 90.9%) compared with the CL (21.8g/d; 94.0%), FL (15.5g/d; 95.4%), and DL (4.6g/d; 98.5%) treatments, whereas whole-tract digestibility of crude fat was lower for the EL treatment (64.8%) compared with the CL (71.3%), FL (78.5%), and DL (80.4%) treatments. The proportion of C18:3n-3 (g/100g of FA) was higher for the FL treatment compared with the other treatments in plasma triacylglycerols (FL, 3.60; CL, 1.22; EL, 1.35; DL, 1.12) and milk fat (FL, 3.19; CL, 0.87; EL, 0.83; DL, 0.46). Omasal flow and proportion of C18:0 in plasma and milk fat were lower, whereas omasal flow and proportions of biohydrogenation intermediates in plasma and milk fat were higher for the DL treatment compared with the other linseed treatments. The results demonstrate that feeding EL did not result in a higher C18:3n-3 proportion in plasma and milk fat despite the higher omasal C18:3n-3 flow. This was related to the decreased total-tract digestibility of crude fat. Feeding FL resulted in a higher C18:3n-3 proportion in plasma and milk fat, although the omasal C18:3n-3 flow was similar or lower than for the CL and EL treatment, respectively. Feeding DL inhibited biohydrogenation of trans-11,cis-15-C18:2 to C18:0, as indicated by the increased omasal flows and proportions of biohydrogenation intermediates in plasma and milk fat.

Application of tutorial manner cultivating model in the building of nursing manager team

Objective To explore the effect of tutorial manner cultivating model on the building of nursing manager team.Methods Many methods were used such as set post conditions,selected tutors and reserve talents,signed one commission and trained the reserve talents according to the schedule,the all-round support were offered by nursing department and supervision carried by the assessment group of the hospital.Results The comprehensive qualities of the reserve talents and the tutors were improved significantly.The bachelor degree of reserve talents significantly increased from 35％ in 2008 to 90％ in 2010 ( x2 =12.91,P ＜0.05),intermediate title proportion increased from 10％ to 30％.In 2010 annual assessment,excellent rate from 0％ to 40％ ( x2 =10.00,P ＜ 0.05 ).The bachelor degree of the tutors obviously increased from 42.9％ to 85％,senior title proportion significantly increased from 14.3％ to 42.9％ ( x2 =3.5,2.8,respectively ; P ＜0.05).At the same time,the tutorial manner training mode also promoted the whole quality of nursing management team,the average age of nursing management team from42 to 39,the bachelor degree or above increased from 33 ％ to 88 ％ ( P ＜ 0.05 ).In 2010,the quality of published papers were marked improved ( P ＜0.05).Conclusions The cultivating model of tutorial manner for hospital set up a business in pure,high quality and strong ability of nursing management reserve talents team.Meanwhile,it improve the overall quality of nursing management team and the quality of nursing. Key words: Nursing management research; Tutorial manner cultivating model; Personnel training

The Fanconi Anemia Ortholog FANCM Ensures Ordered Homologous Recombination in Both Somatic and Meiotic Cells in Arabidopsis

The human hereditary disease Fanconi anemia leads to severe symptoms, including developmental defects and breakdown of the hematopoietic system. It is caused by single mutations in the FANC genes, one of which encodes the DNA translocase FANCM (for Fanconi anemia complementation group M), which is required for the repair of DNA interstrand cross-links to ensure replication progression. We identified a homolog of FANCM in Arabidopsis thaliana that is not directly involved in the repair of DNA lesions but suppresses spontaneous somatic homologous recombination via a RecQ helicase (At-RECQ4A)-independent pathway. In addition, it is required for double-strand break-induced homologous recombination. The fertility of At-fancm mutant plants is compromised. Evidence suggests that during meiosis At-FANCM acts as antirecombinase to suppress ectopic recombination-dependent chromosome interactions, but this activity is antagonized by the ZMM pathway to enable the formation of interference-sensitive crossovers and chromosome synapsis. Surprisingly, mutation of At-FANCM overcomes the sterility phenotype of an At-MutS homolog4 mutant by apparently rescuing a proportion of crossover-designated recombination intermediates via a route that is likely At-MMS and UV sensitive81 dependent. However, this is insufficient to ensure the formation of an obligate crossover. Thus, At-FANCM is not only a safeguard for genome stability in somatic cells but is an important factor in the control of meiotic crossover formation.

Predicting the Effect of Surface Texture on the Qualitative Form of Prehension

Reach-to-grasp movements change quantitatively in a lawful (i.e. predictable) manner with changes in object properties. We explored whether altering object texture would produce qualitative changes in the form of the precontact movement patterns. Twelve participants reached to lift objects from a tabletop. Nine objects were produced, each with one of three grip surface textures (high-friction, medium-friction and low-friction) and one of three widths (50 mm, 70 mm and 90 mm). Each object was placed at three distances (100 mm, 300 mm and 500 mm), representing a total of 27 trial conditions. We observed two distinct movement patterns across all trials—participants either: (i) brought their arm to a stop, secured the object and lifted it from the tabletop; or (ii) grasped the object ‘on-the-fly’, so it was secured in the hand while the arm was moving. A majority of grasps were on-the-fly when the texture was high-friction and none when the object was low-friction, with medium-friction producing an intermediate proportion. Previous research has shown that the probability of on-the-fly behaviour is a function of grasp surface accuracy constraints. A finger friction rig was used to calculate the coefficients of friction for the objects and these calculations showed that the area available for a stable grasp (the ‘functional grasp surface size’) increased with surface friction coefficient. Thus, knowledge of functional grasp surface size is required to predict the probability of observing a given qualitative form of grasping in human prehensile behaviour.

Microneurographic identification of spontaneous activity in C-nociceptors in neuropathic pain states in humans and rats

C-nociceptors do not normally fire action potentials unless challenged by adequate noxious stimuli. However, in pathological states nociceptors may become hyperexcitable and may generate spontaneous ectopic discharges. The aim of this study was to compare rat neuropathic pain models and to assess their suitability to model the spontaneous C-nociceptor activity found in neuropathic pain patients. Studies were performed in normal rats (n = 40), healthy human subjects (n = 15), peripheral neuropathic pain patients (n = 20), and in five rat neuropathic pain models: nerve crush (n = 24), suture (n = 14), chronic constriction injury (n = 12), STZ-induced diabetic neuropathy (n = 56), and ddC-induced neuropathy (n = 15). Microneurographic recordings were combined with electrical stimulation to monitor activity in multiple C fibers. Stimulation at 0.25 Hz allowed spontaneous impulses to be identified by fluctuations in baseline latency. Abnormal latency fluctuations could be produced by several mechanisms, and spontaneous activity was most reliably identified by the presence of unexplained latency increases corresponding to two or more additional action potentials. Spontaneous activity was present in a proportion of mechano-insensitive C-nociceptors in the patients and all rat models. The three focal traumatic nerve injury models provided the highest proportion (59.5%), whereas the two polyneuropathy models had fewer (18.6%), and the patients had an intermediate proportion (33.3%). Spontaneously active mechano-sensitive C-nociceptors were not recorded. Microneurographic recordings of spontaneous activity in diseased C-nociceptors may be useful for both short- and long-term drug studies, both in animals and in humans.

Dinámica de la especialización en america latina: fragmentación de la producción y sofisticación de las exportaciones

El proceso de globalización ha producido una fuerte transformación de la economía internacional en las últimas décadas, ampliándose el espectro de actividad económica que es factible de ser intercambiada entre países. Los cambios tecnológicos y otros factores que afectan los costos de comercio han dado lugar a nuevos motivos para la especialización. Esta ola se caracteriza por la fragmentación de la producción en muchas etapas y se ha extendido a un variado conjunto de actividades. Así se han desarrollado las denominadas Cadenas Globales de Valor (CGV), combinando la participación de gran cantidad de proveedores en todo el mundo. En particular este fenómeno se expresa en la producción de manufacturas modernas que incorporan un alto nivel de progreso técnico. América Latina, a diferencia de otras regiones en desarrollo, no ha sido un participante protagónico de esta dinámica, y su canasta de productos exportados se caracteriza por un bajo nivel de sofisticación. Este trabajo presenta una caracterización de la inserción en dicho proceso de algunos países de la región seleccionados (Argentina, Brasil, Colombia, Costa Rica, México, Perú y Uruguay), en comparación con algunos países desarrollados (Alemania, Bélgica, Corea del Sur, Estados Unidos y Japón) y con los denominados BRIC. Los resultados obtenidos muestran que en la región se han comenzado a exportar con ventaja comparativa productos no exportados anteriormente, exportados episódicamente o exportados sin ventajas comparativas reveladas. Sin embargo, el desempeño de los países latinoamericanos seleccionados ha sido dispar en términos de proporción de productos intermedios en esa canasta y de sofisticación de los mismos.

Changes in relative abundance of snowshoe hares (Lepus americanus) across a 265-year gradient of boreal forest succession

Understory regeneration within canopy gaps in old-growth boreal forests may provide suitable habitat for wildlife typically associated with early-seral stages, leading to an increase in their abundance in late succession. We surveyed a chronosequence of postfire (17–265 years) and postharvest (3–63 years) stands in Canada’s eastern boreal forest to determine whether snowshoe hares ( Lepus americanus Erxleben, 1777) followed a bimodal abundance distribution with stand age that reflects changes in food and cover during postdisturbance succession. A strong peak in relative hare abundance occurred during the first 80 years of succession, with highest faecal pellet densities observed between 40 and 50 years after disturbance. Changes in hare abundance during this period were similar among fire- and clearcut-origin stands and closely tracked changes in lateral cover and vertical cover. Pellet density increased again in stands >180 years. Variation in hare abundance during late succession was partially mediated by gap dynamics, with highest pellet densities in stands occupied by an intermediate proportion of mortality-origin canopy gaps. Hares thus undergo rapid changes in abundance during early succession followed by a much longer period of subtle changes in density as stands develop old-growth structure. Shifting forest age-class distribution induced by forest management could therefore significantly alter regional spatiotemporal dynamics of snowshoe hares.

Molecular Investigation of Resistance to the Antituberculous Drug Ethionamide in Multidrug-Resistant Clinical Isolates of Mycobacterium tuberculosis

Ethionamide (ETH) needs to be activated by the mono-oxygenase EthA, which is regulated by EthR, in order to be active against Mycobacterium tuberculosis. The activated drug targets the enzyme InhA, which is involved in cell wall biosynthesis. Resistance to ETH has been reported to result from various mechanisms, including mutations altering EthA/EthR, InhA and its promoter, the NADH dehydrogenase encoded by ndh, and the MshA enzyme, involved in mycothiol biosynthesis. We searched for such mutations in 87 clinical isolates: 47 ETH-resistant (ETH(r)) isolates, 24 ETH-susceptible (ETH(s)) isolates, and 16 isolates susceptible to ETH but displaying an intermediate proportion of resistant cells (ETH(Sip); defined as ≥1% but <10% resistant cells). In 81% (38/47) of the ETH(r) isolates, we found mutations in ethA, ethR, or inhA or its promoter, which mostly corresponded to new alterations in ethA and ethR. The 9 ETH(r) isolates without a mutation in these three genes (9/47, 19%) had no mutation in ndh, and a single isolate had a mutation in mshA. Of the 16 ETH(Sip) isolates, 7 had a mutation in ethA, 8 had no detectable mutation, and 1 had a mutation in mshA. Finally, of the 24 ETH(s) isolates, 23 had no mutation in the studied genes and 1 displayed a yet unknown mutation in the inhA promoter. Globally, the mechanism of resistance to ETH remained unknown for 19% of the ETH(r) isolates, highlighting the complexity of the mechanisms of ETH resistance in M. tuberculosis.

PAH intermediates: Links between the atmosphere and biological systems

China is now the world's largest emitter of polycyclic aromatic hydrocarbons (PAHs). In addition, PAHs, and their reactive intermediates, undergo trans-Pacific atmospheric transport to the Western U.S. The objectives of our research are to predict, identify and quantify novel PAH intermediates in the atmosphere and biological systems, using computational methods, as well as laboratory and field experiments. Gaussian is used to predict the thermodynamic properties of parent structure PAHs, as well as the associated nitro-, oxy-, and hydroxy-PAH intermediates. Based on these predictions, state-of-the-art analytical chemistry techniques are used to identify and quantify these potential intermediates on Asian particulate matter before and after reaction in a continuous flow photochemical reactor. These same techniques are used to identify the relative proportion of PAH intermediates in PAH source regions (such as Beijing, China) and during long-range atmospheric transport to the Western U.S. PAH personal exposure studies in China and the Confederated Tribes of the Umatilla Indian Reservation in Oregon will be used to assess the similarities and differences in the PAH intermediates in biological systems relative to the atmosphere.

Desmosterol, the main sterol in rabbit semen: distribution among semen subfractions and its role in the in vitro spermatozoa acrosome reaction and motility.

Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form (94.3%), were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol (58.5% of total sterols) and cholesterol (35.9% of total sterols). Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% (in the prostatic secretory granules, PSGs) to 63.8% (in the seminal plasma). Spermatozoa contained an intermediate proportion of desmosterol (59.8%), which was asymmetrically distributed between the heads (52.0% of the total content of sterols) and the tails (81.8%). Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L(-1). In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation.