Metallomics and chemical speciation: towards a better understanding of metal-induced stress in plants

Most metal ions are toxic to plants, even at low concentrations, despite the fact that some are essential for growth and play key roles in metabolism. The majority of metals induce the formation of reactive oxygen species, which require the synthesis of additional antoxidant compounds and enzymes for their removal. New techniques that have greatly improved the identification, localisation and quantification of metals within plant tissues have led to the science of metallomics. This advancement in knowledge should eventually allow the characterisation of plants used in the process of phytoremediation of soils contaminated with toxic metals.

Soil CO(2) emission estimated by different interpolation techniques

Soil CO(2) emissions are highly variable, both spatially and across time, with significant changes even during a one-day period. The objective of this study was to compare predictions of the diurnal soil CO(2) emissions in an agricultural field when estimated by ordinary kriging and sequential Gaussian simulation. The dataset consisted of 64 measurements taken in the morning and in the afternoon on bare soil in southern Brazil. The mean soil CO(2) emissions were significantly different between the morning (4.54 mu mol m(-2) s(-1)) and afternoon (6.24 mu mol m(-2) s(-1)) measurements. However, the spatial variability structures were similar, as the models were spherical and had close range values of 40.1 and 40.0 m for the morning and afternoon semivariograms. In both periods, the sequential Gaussian simulation maps were more efficient for the estimations of emission than ordinary kriging. We believe that sequential Gaussian simulation can improve estimations of soil CO(2) emissions in the field, as this property is usually highly non-Gaussian distributed.

Reproductive cycles in Bos indicus cattle

Several studies using transrectal ovarian ultrasonic scanning in Bos taurus (B. taurus) cattle and more recently in Bos indicus (B. Indicus) females evaluated the reproductive cycles of heifers and cows under different conditions. In general, B. indicus cattle have more follicles and more follicular waves during the estrous cycle and ovulate from smaller follicles than B. taurus. Consequently B. indicus females have smaller corpora lutea and it is assumed circulating concentrations of estradiol and progesterone are also less. However, these findings may vary depending on the nutritional status and regimen in which the animals are managed. Moreover, there are significant differences between B. taurus and B. indicus regarding follicle size at the time of deviation of the dominant follicle. These differences in ovarian function between B. indicus and B. taurus, e.g. greater antral follicle population are, probably, the main reasons for the great success of in vitro embryo production programs in Zebu cattle, especially in Brazil. (C) 2011 Elsevier B.V. All rights reserved.

Allele-Specific Expression of the MAOA Gene and X Chromosome Inactivation in In Vitro Produced Bovine Embryos

During embryogenesis, one of the two X chromosomes is inactivated in embryos. The production of embryos in vitro may affect epigenetic mechanisms that could alter the expression of genes related to embryo development and X chromosome inactivation (XCI). The aim of this study was to understand XCI during in vitro, pre-implantation bovine embryo development by characterizing the allele-specific expression pattern of the X chromosome-linked gene, monoamine oxidase A (MAOA). Two pools of ten embryos, comprised of the 4-, 8- to 16-cell, morula, blastocyst, and expanded blastocyst stages, were collected. Total RNA from embryos was isolated, and the RT-PCR-RFLP technique was used to observe expression of the MAOA gene. The DNA amplicons were also sequenced using the dideoxy sequencing method. MAOA mRNA was detected, and allele-specific expression was identified in each pool of embryos. We showed the presence of both the maternal and paternal alleles in the 4-, 8-to 16-cell, blastocyst and expanded blastocyst embryos, but only the maternal allele was present in the morula stage. Therefore, we can affirm that the paternal X chromosome is totally inactivated at the morula stage and reactivated at the blastocyst stage. To our knowledge, this is the first report of allele-specific expression of an X-linked gene that is subject to XCI in in vitro bovine embryos from the 4-cell to expanded blastocyst stages. We have established a pattern of XCI in our in vitro embryo production system that can be useful as a marker to assist the development of new protocols for in vitro embryo production. Mol. Reprod. Dev. MoL Reprod. Dev. 77: 615-621, 2010. (C) 2010 Wiley-Liss, Inc.

Seasonal variation of peptidase activities in the reproductive tract of Crotalus durissus terrificus

Seasonal quantitative patterns of acid (APA), basic (APB), puromycin-sensitive (APN-PS) and puromycin-insensitive neutral (APN-PI), cystyl (CAP), dipeptidyl IV (DPPIV), type-1 pyroglutamyl (PAP-I) and prolylimino (PIP) aminopeptidases and prolyl oligopeptidase (POP) activities in soluble (SF) and solubilized membrane-bound (MF) fractions from ductus deferens, vagina and uterus were studied to evaluate their relationships with the reproductive cycle and the extensive long-term spermatozoa storage (LTSS) of the Neotropical rattlesnake Crotalus durissus terrificus. APB, PIP and POP were detected only in SF, while other peptidases were detected in SF and MF. APB, APN-PI and APN-PS were predominant in most tissues in all seasons. Peptidase activities had a common pattern of increment during the dry season (winter/autumn), which coincides with the mating period (autumn) and LTSS in the female (winter), as well as the reduction of spermatozoa motility and maintenance of fertilization capacity of spermatozoa. The high CAP activity in the soluble fraction of the vagina during winter, compared to summer (time of parturition) and spring, coincides with the relaxation of this tissue. In the soluble fraction, the low PAP-1 activity of the ductus deferens coincided with its high activity in the vagina during the winter; and the inverse occurred in summer, which is consistent with the physiological process of preserving spermatozoon viability. In conclusion, the studied peptidase activities had seasonal and tissue-specific characteristics, which suggest a relevant role in the reproductive physiology of C. d. terrificus. (C) 2008 Elsevier Inc. All rights reserved.

Ultrasound-assisted synthesis of symmetrical biaryls by palladium-catalyzed detelluration of 1,2-diaryiditellanes

An ultrasound-assisted synthesis of functionalized symmetrical biaryls with electron-withdrawing or electron-donating substituents is described and illustrated by the palladium-catalyzed detelluration of 1,2-diarylditellanes. This procedure offers easy access to symmetrical biaryls in short reaction time and the products are achieved in good to excellent yields. (c) 2009 Published by Elsevier Ltd.

Ultrasound-Assisted Synthesis of Symmetrical Biaryls by Palladium-Catalyzed Homocoupling of Aryl n-Butyl Tellurides

An ultrasound-assisted synthesis of symmetrical biaryls with electron-withdrawing or -donating substituents is described and illustrated by palladium-catalyzed homocoupling reaction of aryl tellurides. This procedure offers easy access to biaryls in short reaction time, and the products are achieved in good to excellent yields.

Biophysical techniques used to evaluate the stratum corneum

Assortments of biophysical methods are used to the study the stratum corneum morphology and dynamic with the objective to elucidate the correlation between its structure and functions. Among these methods, there are: X-ray diffraction, electron paramagnetic resonance, differential scanning calorimetry, Raman spectroscopy with Fourrier transform, infrared spectroscopy and photoacustic spectroscopy. In this manuscript, methods are presented and discussed in relation to the use indication, interpretation of results and advantages and limitations to the stratum corneum analysis.

Ultrasound-assisted synthesis of functionalized 1,3-enynes by palladium-catalyzed cross-coupling reaction of alpha-styrylbutyltelluride with alkynyltrifluoroborate salts

An ultrasound-assisted synthesis of functionalized 1,3-enyne scaffolds is described and illustrated by palladium-catalyzed cross-coupling of potassium alkynyltrifluoroborate salts and alpha-styrylbutyltellurides. This procedure offers easy access to 1,3-enyne architecture that contains aliphatic and aromatic groups in good to excellent yields.

Chemical Signals in the Stingless Bee, Frieseomelitta varia, Indicate Caste, Gender, Age, and Reproductive Status

Chemical compounds on the cuticle are a rich source of information used during interactions among social insects. Despite the multitude of studies on these substances and their function in ants, wasps, and honeybees, little is known about this subject in stingless bees (Hymenoptera: Apidae, Meliponini). We studied the chemical composition of the cuticle of the stingless bee, Frieseomelitta varia, by gas chromatography-mass spectrometry (GC-MS), to investigate potential chemical variation among castes, gender, age, and reproductive status. We found differences in the cuticular hydrocarbon composition among workers, males, and queens, recording both qualitative and quantitative differences among individuals of different ages and gender. The cuticle of physogastric queens presented a chemical profile that was distinct from all other groups in the analysis, with high relative abundances of alkenes and alkadienes with 27, 29, and 31 carbon atoms. We discuss the possibility that these compounds signal a queen`s presence to the colony, thereby initiating all vital worker-queen interactions.

Mercury speciation in seafood samples by LC-ICP-MS with a rapid ultrasound-assisted extraction procedure: Application to the determination of mercury in Brazilian seafood samples

This paper describes a simple method for mercury speciation in seafood samples by LC-ICP-MS with a fast sample preparation procedure. Prior to analysis, mercury species were extracted from food samples with a solution containing mercaptoethanol, L-cysteine and HCl and sonication for 15 min. Separation of mercury species was accomplished in less than 5 min on a C8 reverse phase column with a mobile phase containing 0.05%-v/v mercaptoethanol, 0.4% m/v L-cysteine and 0.06 mol L(-1) ammonium acetate. The method detection limits were found to be 0.25, 0.20 and 0.1 ng g(-1) for inorganic mercury, ethylmercury and methylmercury, respectively. Method accuracy is traceable to Certified Reference Materials (DOLT-3 and DORM-3) from the National Research Council Canada (NRCC). With the proposed method there is a considerable reduction of the time of sample preparation. Finally, the method was applied for the speciation of mercury in seafood samples purchased from the Brazilian market. (C) 2010 Elsevier Ltd. All rights reserved.

Effects of methylmercury on male reproductive functions in Wistar rats

In this study we investigated the effects of subacute exposure to methylmercury (MeHg) on male reproductive functions in rats by means of determination of alterations in structural and functional parameters. Adult male Wistar rats received 0, 0.5, 1.0 or 3.0 mg/kg/body weight/day orally, daily MeHg for 14 days. Sperm motility, the relative sperm count and transit time in the caput/corpus epididymis, were all reduced at all doses. The lowest dose increased the number of sperm head abnormalities; daily sperm production was elevated at the intermediate dose; while at the highest dose there was a decrease in serum testosterone levels and a rise in mercury (Hg) content in reproductive organs, liver and kidneys. In conclusion, MeHg exposure produced damages on male reproductive functions which may be attributed, at least in part, to the reduction in serum testosterone levels. These consequences could potentially result in infertility in rats. (C) 2011 Elsevier Inc. All rights reserved.

Mercury speciation in whole blood by gas chromatography coupled to ICP-MS with a fast microwave-assisted sample preparation procedure

A simple and fast method is described for simultaneous determination of methylmercury (MeHg), ethylmercury (Et-Hg) and inorganic mercury (Ino-Hg) in blood samples by using capillary gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) after derivatization and alkaline digestion. Closed-vessel microwave assisted digestion conditions with tetramethylammonium hydroxide (TMAH) have been optimized. Derivatization by using ethylation and propylation procedures have also been evaluated and compared. The absolute detection limits (using a 1 mu L injection) obtained by GC-ICP-MS with ethylation were 40 fg for MeHg and Ino-Hg, respectively, and with propylation were 50, 20 and 50 fg for MeHg, Et-Hg and Ino-Hg, respectively. Method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from the National Institute of Standards and Technology (NIST). Additional validation is provided based on the comparison of results obtained for mercury speciation in blood samples with the proposed procedure and with a previously reported LC-ICP-MS method. With the new proposed procedure no tedious clean-up steps are required and a considerable improvement of the time of analysis was achieved compared to other methods using GC separation.

Exploratory Approach to the use of Techniques of Regression Analysis and Pooled Analysis in Studies of Consumer Behavior

This paper is part of a large study to assess the adequacy of the use of multivariate statistical techniques in theses and dissertations of some higher education institutions in the area of marketing with theme of consumer behavior from 1997 to 2006. The regression and conjoint analysis are focused on in this paper, two techniques with great potential of use in marketing studies. The objective of this study was to analyze whether the employement of these techniques suits the needs of the research problem presented in as well as to evaluate the level of success in meeting their premisses. Overall, the results suggest the need for more involvement of researchers in the verification of all the theoretical precepts of application of the techniques classified in the category of investigation of dependence among variables.

Male Reproductive Apparatus and Spermatophore Morphology of the Hermit Crabs Pagurus brevidactylus and P. criniticornis (Anomura, Paguridae)

Spermatozoa of most crustacean species are nonmotile and are packed into spermatophores. In Decapoda, spermatophores are highly variable in morphology and can be useful in the solving of taxonomic and systematic questions, especially among the Anomura. In this study, the morphology and morphometry of the spermatophores of the western Atlantic hermit crabs Pagurus brevidactylus and P criniticornis are described. The abdomen of fresh male specimens was dissected to expose the reproductive system and to extract the spermatophores, which were analyzed by stereoscopic, light, and scanning electron microscopy. The vas deferens can be divided macroscopically in three regions, all of them containing spermatophores. Tripartite spermatophores are composed of an elongated cylindrical main ampulla, a triangular accessory ampulla, a narrow cylindrical peduncle, and a round pedestal. Dimensions of the spermatophore components are positively correlated to the size of the crab. Morphological patterns observed in this study resemble those of other pagurid hermit crabs investigated to date. The morphological character distribution confirms classifications based on adult morphology and molecular analysis. J. Morphol. 272:1271-1280, 2011. (C) 2011 Wiley-Liss, Inc.