The role of seed dispersal,pollination and historical effects on genetic patterns of an insular plant that has lost its only seed disperser

Aim The genetic structure of many plant species is heavily dependent on their pollinators and seed dispersers, and can thus be altered if either of the associated mutualistic interactions is disrupted. In this study we assess the genetic diversity and structure and infer the seed/pollen gene‐flow patterns among insular populations of Daphne rodriguezii, a shrub pollinated and dispersed by animals that has lost its only disperser (the lizard Podarcis lilfordi) in most of its populations. Location The island of Menorca and the islet of Colom (Balearic Islands, Western Mediterranean). Methods To assess the contribution of gene flow via pollen and seeds to the genetic structure of D. rodriguezii we used amplified fragment length polymorphisms (AFLPs; seeds and pollen) and plastid DNA sequences (cpDNA; seeds). We sampled individuals from all population nuclei of the species (12–19 adults per population): one population in Colom, where the plant–lizard interaction persists, and four in Menorca, where the seed dispersal mutualism disappeared with the extinction of the lizard. Results The highest heterozygosity values were found in Colom and in its closest population (Favàritx), whereas values were lower in the smallest Menorcan populations, which also had higher relatedness among individuals. We found distinct genetic signals between AFLP and cpDNA analyses. While AFLP markers showed low differentiation between populations, cpDNA showed a clear differentiation between them. Main conclusions Our results point to negative impacts of the disperser loss on genetic diversity and relatedness in the smaller and more isolated populations. They also suggest an old isolation by seeds, probably occurring well before the extinction of the lizard (c. 2000 years ago). Gene flow was maintained via pollination; however, the seed disperser loss may ultimately hinder pollinator‐mediated gene flow, as a result of reduced probabilities of effective pollination among increasingly distant and scarce individuals.     

Survival and growth of tree seedlings in anthropogenically disturbed Mexican montane rain forests

Abstract. The montane rain forest in Chiapas, Mexico has been subject to continuous human disturbance, mainly by wood extraction, cattle grazing and fire. To address the effect of this kind of disturbance regime on regeneration, survival and growth of naturally established tree seedlings were evaluated during a 3‐yr period in three forest stands which varied in frequency and intensity of human disturbance. Frequency of cattle browsing on transplanted seedlings of Cornus disciflora, Liquidambar styraciflua and Oreopanax xalapensis planted on different facing slopes was evaluated over an 18‐mo period, their survival and growth was also determined. The density of seedlings, number of species and survival of naturally recruited tree seedlings decreased with increased intensity of disturbance. Only seedlings of Pinus and Quercus species were recorded in heavily disturbed conditions. Seedlings grew more vigorously under moderately disturbed than in undisturbed or heavily disturbed conditions. More extreme microclimatic variation (air temperature, relative humidity and solar radiation) was recorded in heavily vs moderately disturbed forest. Survival and growth of transplanted tree seedlings differed with species. Grazing damage varied among seedlings located on different facing slopes. Plants located on NE facing slopes survived better than those on other slope positions. The mean proportion of surviving individuals of L. styraciflua (80%) and C. disciflora (78%) was higher than those for O. xalapensis (60%). A higher number of C. disciflora and O. xalapensis seedlings were grazed than L. styraciflua in any slope orientation treatment. The results suggest that human disturbance negatively affects natural recruitment, reduces richness of tree seedlings and favours a small number of tree species.     

The Mitochondrial Genetic Diversity of the Olive Field Mouse Abrothrix olivacea (Cricetidae; Abrotrichini) is Latitudinally Structured Across Its Geographic Distribution

Although the mitochondrial diversity of Abrothrix olivacea has been widely studied, the phylogeographic structure and the historical demography of this species are still not fully comprehended. With the aim of better understanding these aspects, a 801 bp fragment of the Cytb gene sampled in 416 individuals (202 from Argentina and 214 from Chile) collected at 103 localities (46 from Argentina and 57 from Chile) was analyzed. This represents the most geographically and numerically widespread sampling used until now to study the mitochondrial variation of this species. The results obtained indicate that the mitochondrial diversity of A. olivacea is structured in four main phylogroups with barely overlapped geographic ranges that replace each other mostly latitudinally from northern Chile (ca. 18° S) to the Isla Grande of Tierra del Fuego (ca. 56° S). In turn, each mitochondrial phylogroup shows distinct crown ages and signals of asynchronous population expansions. Overall, the results obtained here improve the delimitation of the geographic ranges of the intraspecific mitochondrial lineages of this species and suggest that its subspecific taxonomy require an exhaustive revision. In addition, the pattern of genetic structure described here for the Patagonian-Fuegian populations differs from that evidenced by the characterization of nuclear variation. This mito-nuclear discordance could be associated with neutral demographic dynamics and the vagaries of allele sorting and suggest that the evolutionary history of this species could be more complex than that reconstructed from the isolated study of mitochondrial or nuclear variability.

     

Low Efficacy of Pegylated Interferon plus Ribavirin plus Nitazoxanide for HCV Genotype 4 and HIV Coinfection

Background

Nitazoxanide (NTZ) plus pegylated interferon and ribavirin (Peg-IFN/RBV) improved the sustained virological response (SVR) achieved with Peg-IFN/RBV in hepatitis C virus genotype 4 (HCV-4)-monoinfected patients. There are no data currently on the efficacy of Peg-IFN/RBV plus NTZ for human immunodeficiency virus (HIV)/HCV-4 coinfection. Therefore, the objectives of this clinical trial were to assess the efficacy and to evaluate the safety of Peg-IFN/RBV plus NTZ in HIV/HCV-4-coinfected patients.

Patients and Methods

This was an open-label, single arm, multicenter phase II pilot clinical trial ({"type":"clinical-trial","attrs":{"text":"NCT01529073","term_id":"NCT01529073"}}NCT01529073) enrolling HIV-infected individuals with HCV-4 chronic infection, naïve to HCV therapy. Patients were treated with NTZ 500 mg bid for 4 weeks, followed by NTZ 500 mg bid plus Peg-IFN alpha-2b 1.5 μg/kg/week plus weight-adjusted RBV during 48 weeks. Analyses were done by intention-to-treat (ITT, missing = failure). A historical cohort of HIV/HCV-4-infected patients treated with Peg-IFN alpha-2b and RBV at the same area was used as control.

Results

Two (9.5%) of 21 patients included in the trial compared with 5 (21.7%) of 23 patients included in the historical cohort achieved SVR (SVR risk difference, -12.2%; 95% confidence interval, -33.2% to 8.8%; p = 0.416). Virological failure was due to lack of response in 13 (62%) individuals recruited in the trial. Two (9.5%) patients included in the trial and two (9.5%) individuals from the historical cohort discontinued permanently due to adverse events.

Conclusions

No increase in SVR was observed among HIV/HCV-4-coinfected patients receiving Peg-IFN/RBV plus NTZ compared with a historical cohort treated with Peg-IFN/RBV. Interruptions due to adverse events of Peg-IFN/RBV plus NTZ were similar to those of dual therapy.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01529073","term_id":"NCT01529073"}}NCT01529073     

Single nucleotide polymorphism discovery in common bean

Single nucleotide polymorphisms (SNPs) were discovered in common bean (Phaseolus vulgaris L.) via resequencing of sequence-tagged sites (STSs) developed by PCR primers previously designed to soybean shotgun and bacterial artificial chromosome (BAC) end sequences, and by primers designed to common bean genes and microsatellite flanking regions. DNA fragments harboring SNPs were identified in single amplicons from six contrasting P. vulgaris genotypes of the Andean (Jalo EEP 558, G 19833, and AND 277) and Mesoamerican (BAT 93, DOR 364, and Rudá) gene pools. These genotypes are the parents of three common bean recombinant inbred line mapping populations. From an initial set of 1,880 PCR primer pairs tested, 265 robust STSs were obtained, which could be sequenced in each one of the six common bean genotypes. In the resulting 131,120?bp of aligned sequence, a total of 677 SNPs were identified, including 555 single-base changes (295 transitions and 260 transversions) and 122 small nucleotide insertions/deletions (indels). The frequency of SNPs was 5.16 SNPs/kb and the mean nucleotide diversity, expressed as Halushka??s theta, was 0.00226. This work represents one of the first efforts aimed at detecting SNPs in P. vulgaris. The SNPs identified should be an important resource for common bean geneticists and breeders for quantitative trait locus discovery, marker-assisted selection, and map-based cloning. These SNPS will be also useful for diversity analysis and microsynteny studies among legume species.     

Observation and establishment of gonad development stages in polyplacophorans (Mollusca): Chiton (Chiton) articulatus a case study

Gonad development stages (GDS) and, subsequently, the reproductive cycle are described by performing histology of some gonad portions. In polyplacophorans, gametogenesis is not enough to define GDS; further anatomical gonad features are relevant. In most adult polyplacophorans, the gonad is a simple anatomical structure that resembles and operates as one single gonadal acinus without glandular structure. These features have gone unnoticed causing inaccurate GDS assignment and, consequently, imprecise reproductive season in polyplacophorans. Here, dissection protocols that allow extracting a compact gonad are established. Emphasizing the anatomical structure of the whole gonad and the displacement of gametes, five GDS were assigned to both sexes of Chiton (Chiton) articulatus: I‐goniogenesis, II‐development, III‐ripe, IV‐spawning, V‐rest. Tissue platelets contribute importantly to GDS assignment and even help distinguishing between males and females. Neither a randomly selected portion of gonad nor a longitudinal section are recommended because it leads to misinterpretation higher than 50% in determining GDS and besides ignores displacement of gametes. A panoramic sweep across a complete transverse‐section of each gonad was validated as the best option for establishing GDS. This new methodology was tested on several polyplacophorans species, and seems generally applicable for histological assessment of reproductive cycle and reproductive season in polyplacophorans.     

Roundness variation in JPEG images affects the automated process of nuclear immunohistochemical quantification: correction with a linear regression model

The volume of digital image (DI) storage continues to be an important problem in computer-assisted pathology. DI compression enables the size of files to be reduced but with the disadvantage of loss of quality. Previous results indicated that the efficiency of computer-assisted quantification of immunohistochemically stained cell nuclei may be significantly reduced when compressed DIs are used. This study attempts to show, with respect to immunohistochemically stained nuclei, which morphometric parameters may be altered by the different levels of JPEG compression, and the implications of these alterations for automated nuclear counts, and further, develops a method for correcting this discrepancy in the nuclear count. For this purpose, 47 DIs from different tissues were captured in uncompressed TIFF format and converted to 1:3, 1:23 and 1:46 compression JPEG images. Sixty-five positive objects were selected from these images, and six morphological parameters were measured and compared for each object in TIFF images and those of the different compression levels using a set of previously developed and tested macros. Roundness proved to be the only morphological parameter that was significantly affected by image compression. Factors to correct the discrepancy in the roundness estimate were derived from linear regression models for each compression level, thereby eliminating the statistically significant differences between measurements in the equivalent images. These correction factors were incorporated in the automated macros, where they reduced the nuclear quantification differences arising from image compression. Our results demonstrate that it is possible to carry out unbiased automated immunohistochemical nuclear quantification in compressed DIs with a methodology that could be easily incorporated in different systems of digital image analysis.     

Erythrocyte Membrane Phosphatidylserine Exposure in Obesity

It has been suggested that increased erythrocyte membrane phosphatidylserine (PS) exposure could contribute to hypercoagulability and hemorheological disturbances in obesity. The aim of our study was to evaluate PS exposure in obese patients and in a control group and to correlate this with hemorheological properties, i.e., erythrocyte aggregability (EA) and deformability, and to evaluate the effect of weight loss on these parameters. An anthropometric and analytical evaluation was performed at baseline and after 3 months on a diet (very low‐calorie diet for 4 weeks and low‐calorie diet for 2 months) on 49 severe or morbid obese patients (37 women, 12 men) and 55 healthy volunteers (39 women, 16 men). PS exposure on erythrocyte membrane was performed by flow cytometry. Erythrocyte aggregation was measured using the Myrenne MA₁ and the Sefam aggregometer. Erythrocyte deformability was determined in a stress diffractometer. Prothrombin fragment F1+2 (F1+2) was determined as a marker of the hypercoagulable state, and plasma malondialdehyde (MDA) as an indicator of oxidative stress. Obese patients had a higher EA index, higher PS exposure on erythrocyte membranes and higher levels of MDA and F1+2. The differences in erythrocyte aggregation and F1+2 between obese patients and the control group were maintained after adjusting for PS exposure. After 3 months of diet, a significant reduction in PS exposure on erythrocyte membrane was observed. Obese patients show increased PS exposure on erythrocyte membrane, with no effect on rheological properties. Increased PS exposure could contribute to hypercoagulability in these patients. Weight loss obtained with diet treatment reduces PS exposure on erythrocyte membrane.