Constant fluctuating asymmetry but not directional asymmetry along the geographic distribution of Drosophila antonietae (Diptera, Drosophilidae)

ABSTRACT The population dynamics of a species tends to change from the core to the periphery of its distribution. Therefore, one could expect peripheral populations to be subject to a higher level of stress than more central populations (the center–periphery hypothesis) and consequently should present a higher level of fluctuating asymmetry. To test these predictions we study asymmetry in wing shape of five populations of Drosophila antonietae collected throughout the distribution of the species using fluctuating asymmetry as a proxy for developmental instability. More specifically, we addressed the following questions: (1) what types of asymmetry occur in populations of D. antonietae? (2) Does the level of fluctuating asymmetry vary among populations? (3) Does peripheral populations have a higher fluctuating asymmetry level than central populations? We used 12 anatomical landmarks to quantify patterns of asymmetry in wing shape in five populations of D. antonietae within the framework of geometric morphometrics. Net asymmetry – a composite measure of directional asymmetry + fluctuating asymmetry – varied significantly among populations. However, once net asymmetry of each population is decomposed into directional asymmetry and fluctuating asymmetry, most of the variation in asymmetry was explained by directional asymmetry alone, suggesting that populations of D. antonietae have the same magnitude of fluctuating asymmetry throughout the geographical distribution of the species. We hypothesize that larval development in rotting cladodes might play an important role in explaining our results. In addition, our study underscores the importance of understanding the interplay between the biology of a species and its geographical patterns of asymmetry.

Contribuição à citogenética de testudines e análise de assimetria flutuante em Eretmochelys imbricata, Cheloniidae

This work has contributed to knowledge of the order Testudines from cytogenetic and morphological point of view. With regard to the aspects proposed cytogenetic characterization of the species Mesoclemmys tuberculata (n = 5), endemic to the Caatinga biomes, through conventional techniques of cytogenetics and molecular levels. This species presented 2n = 58, NF = 64, the first submetacentric pair, the second metacentric and third subtelocentric, and the other microchromosome telocentric. This species showed a nucleolar bearing pair, coincident with the 18S ribosomal rDNA and that proved to be heterochromatic. Small heterochromatic blocks were also found in the centromeres of the largest chromosomes, as well as terminal regions in most other chromosomes of the complement, that were GC +. Telomeric sequences showed variable patterns of signal intensity, with some repeats more intense in microchromosomes and subtly in the larger ones. When compared with other species of the genus, the G-banding patterns showed a marked similarity between them. The first karyotypic description of the species will aid in future studies and the understanding of evolutionary aspects of this family. From the morphological point of view, we carried out studies of fluctuating asymmetry in sea turtle Eretmochelys imbricata, using methods of benchmarking between hatchlings and adults and their implications for natural selection. Data were collected at two different times: first during the spawning female and the second during the outbreak and birth of the nest. The analyzed characteristics consisted of measurements of length and width of front and rear flippers (CANT, LANT, CPOS and LPOS) also collected data on the number of hull plates, side plates (NPL), the surrounding plates (NPCIRC), and plastron; plates power plants (NPP), inframarginais plates (NPIM). With the values of asymmetry we calculated the value of strict heritability for these traits, the calculation was based on only one parent. A nonparametric analysis Mann-Whitneywas performed to compare the groups (females X hatchlings, newborn hatchlings X dead hatchlings). Adult females showed no bilateral fluctuating asymmetry (FA = 0) on the number plates of the hull and plastron, while offspring, living and dead, showed a greater level of variation in these meristic parameters. In the analysis of females x hatchlings we found a significant difference between the levels of asymmetry in hoof plates (p=0.006) an the width of hindlimbs (p=0.001). Levels of FA suggest an accurate indicator as to the viability or maintenance of the individual to the reproductive phase. The coefficient of heritability (h2) of FA , obtained from the regression analysis, showed that both have low and not statistically significant values(p> 0.1). In the case of exclusion of the effective role of genetics in the generation of FA, reproductive strategies based on high number of subsidiaries products, such as those observed in E. imbricata seems to implicate the production of individuals with high level of developmental instability

Ambulacral length with number of pore pairs/tubercles for both species of sea urchins and for six sampling sites to quantify fluctuating asymmetry

The surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.Methods: We used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs and primary tubercles.Results: For both species, the most polluted sampling site, Cortiou, displayed the highest level of FA, while the Maire and East Maire sampling sites displayed the lowest levels. A. lixula revealed systematic differences in FA among sampling sites for all characters and P. lividus showed differences in FA for the number of primary tubercles.Conclusions: Statistical analyses of FA show a concordance between the spatial patterns of FA among sampling sites and the spatial distribution of sewage discharge pollutants in the Cortiou area. High developmental stress in these sampling sites is associated with exposure to high concentrations of heavy metals and many harmful organic substances contained in wastewater. FA estimated from structures with complex symmetry appears to be a fast and reliable tool to detect subtle differences in FA. Its use in biomonitoring programs for inferring anthropogenic and natural environmental stress is suggested.

Tissue specificity in DNA repair: lessons from trinucleotide repeat instability.

DNA must constantly be repaired to maintain genome stability. Although it is clear that DNA repair reactions depend on cell type and developmental stage, we know surprisingly little about the mechanisms that underlie this tissue specificity. This is due, in part, to the lack of adequate study systems. This review discusses recent progress toward understanding the mechanism leading to varying rates of instability at expanded trinucleotide repeats (TNRs) in different tissues. Although they are not DNA lesions, TNRs are hotspots for genome instability because normal DNA repair activities cause changes in repeat length. The rates of expansions and contractions are readily detectable and depend on cell identity, making TNR instability a particularly convenient model system. A better understanding of this type of genome instability will provide a foundation for studying tissue-specific DNA repair more generally, which has implications in cancer and other diseases caused by mutations in the caretakers of the genome.

Targeting Oxidative Stress and Aberrant Critical Period Plasticity in the Developmental Trajectory to Schizophrenia.

Schizophrenia is a neurodevelopmental disorder reflecting a convergence of genetic risk and early life stress. The slow progression to first psychotic episode represents both a window of vulnerability as well as opportunity for therapeutic intervention. Here, we consider recent neurobiological insight into the cellular and molecular components of developmental critical periods and their vulnerability to redox dysregulation. In particular, the consistent loss of parvalbumin-positive interneuron (PVI) function and their surrounding perineuronal nets (PNNs) as well as myelination in patient brains is consistent with a delayed or extended period of circuit instability. This linkage to critical period triggers (PVI) and brakes (PNN, myelin) implicates mistimed trajectories of brain development in mental illness. Strategically introduced antioxidant treatment or later reinforcement of molecular brakes may then offer a novel prophylactic psychiatry.

An Increased Iliocapsularis-to-rectus-femoris Ratio Is Suggestive for Instability in Borderline Hips

BACKGROUND The iliocapsularis muscle is an anterior hip structure that appears to function as a stabilizer in normal hips. Previous studies have shown that the iliocapsularis is hypertrophied in developmental dysplasia of the hip (DDH). An easy MR-based measurement of the ratio of the size of the iliocapsularis to that of adjacent anatomical structures such as the rectus femoris muscle might be helpful in everyday clinical use. QUESTIONS/PURPOSES We asked (1) whether the iliocapsularis-to-rectus-femoris ratio for cross-sectional area, thickness, width, and circumference is increased in DDH when compared with hips with acetabular overcoverage or normal hips; and (2) what is the diagnostic performance of these ratios to distinguish dysplastic from pincer hips? METHODS We retrospectively compared the anatomy of the iliocapsularis muscle between two study groups with symptomatic hips with different acetabular coverage and a control group with asymptomatic hips. The study groups were selected from a series of patients seen at the outpatient clinic for DDH or femoroacetabular impingement. The allocation to a study group was based on conventional radiographs: the dysplasia group was defined by a lateral center-edge (LCE) angle of < 25° with a minimal acetabular index of 14° and consisted of 45 patients (45 hips); the pincer group was defined by an LCE angle exceeding 39° and consisted of 37 patients (40 hips). The control group consisted of 30 asymptomatic hips (26 patients) with MRIs performed for nonorthopaedic reasons. The anatomy of the iliocapsularis and rectus femoris muscle was evaluated using MR arthrography of the hip and the following parameters: cross-sectional area, thickness, width, and circumference. The iliocapsularis-to-rectus-femoris ratio of these four anatomical parameters was then compared between the two study groups and the control group. The diagnostic performance of these ratios to distinguish dysplasia from protrusio was evaluated by calculating receiver operating characteristic (ROC) curves and the positive predictive value (PPV) for a ratio > 1. Presence and absence of DDH (ground truth) were determined on plain radiographs using the previously mentioned radiographic parameters. Evaluation of radiographs and MRIs was performed in a blinded fashion. The PPV was chosen because it indicates how likely a hip is dysplastic if the iliocapsularis-to-rectus-femoris ratio was > 1. RESULTS The iliocapsularis-to-rectus-femoris ratio for cross-sectional area, thickness, width, and circumference was increased in hips with radiographic evidence of DDH (ratios ranging from 1.31 to 1.35) compared with pincer (ratios ranging from 0.71 to 0.90; p < 0.001) and compared with the control group, the ratio of cross-sectional area, thickness, width, and circumference was increased (ratios ranging from 1.10 to 1.15; p ranging from 0.002 to 0.039). The area under the ROC curve ranged from 0.781 to 0.852. For a one-to-one iliocapsularis-to-rectus-femoris ratio, the PPV was 89% (95% confidence interval [CI], 73%-96%) for cross-sectional area, 77% (95% CI, 61%-88%) for thickness, 83% (95% CI, 67%-92%) for width, and 82% (95% CI, 67%-91%) for circumference. CONCLUSIONS The iliocapsularis-to-rectus-femoris ratio seems to be a valuable secondary sign of DDH. This parameter can be used as an adjunct for clinical decision-making in hips with borderline hip dysplasia and a concomitant cam-type deformity to identify the predominant pathology. Future studies will need to prove this finding can help clinicians determine whether the borderline dysplasia accounts for the hip symptoms with which the patient presents. LEVEL OF EVIDENCE Level III, prognostic study.

Efficient developmental mis-targeting by the sporamin NTPP vacuolar signal to plastids in young leaves of sugarcane and Arabidopsis

Plant vacuoles are multi-functional, developmentally varied and can occupy up to 90% of plant cells. The N-terminal propeptide (NTPP) of sweet potato sporamin and the C-terminal propeptide (CTPP) of tobacco chitinase have been developed as models to target some heterologous proteins to vacuoles but so far tested on only a few plant species, vacuole types and payload proteins. Most studies have focused on lytic and protein-storage vacuoles, which may differ substantially from the sugar-storage vacuoles in crops like sugarcane. Our results extend the evidence that NTPP of sporamin can direct heterologous proteins to vacuoles in diverse plant species and indicate that sugarcane sucrose-storage vacuoles (like the lytic vacuoles in other plant species) are hostile to heterologous proteins. A low level of cytosolic NTPP-GFP (green fluorescent protein) was detectable in most cell types in sugarcane and Arabidopsis, but only Arabidopsis mature leaf mesophyll cells accumulated NTPP-GFP to detectable levels in vacuoles. Unexpectedly, efficient developmental mis-trafficking of NTPP-GFP to chloroplasts was found in young leaf mesophyll cells of both species. Vacuolar targeting by tobacco chitinase CTPP was inefficient in sugarcane, leaving substantial cytoplasmic activity of rat lysosomal beta-glucuronidase (GUS) [ER (endoplasmic reticulum)-RGUS-CTPP]. Sporamin NTPP is a promising targeting signal for studies of vacuolar function and for metabolic engineering. Such applications must take account of the efficient developmental mis-targeting by the signal and the instability of most introduced proteins, even in storage vacuoles.

A genetically informed study of the processes underlying the association between parental marital instability and offspring adjustment

Parental divorce is associated with problematic offspring adjustment, but the relation may be due to shared genetic or environmental factors. One way to test for these confounds is to study offspring of twins discordant for divorce. The current analyses used this design to separate the mechanisms responsible for the association between parental divorce, experienced either before or after the age of 16, and offspring well-being. The results were consistent with a causal role of divorce in earlier initiation of sexual intercourse and emotional difficulties, in addition to a greater probability of educational problems, depressed mood, and suicidal ideation. In contrast, the increased risk for cohabitation and earlier initiation of drug use was explained by selection factors, including genetic confounds.

Symptoms of hyperactivity and inattention can mediate deficits of postural stability in developmental dyslexia

DDevelopmental dyslexia is a reading disorder associated with impaired postural control. However, such deficits are also found in attention deficit hyperactivity disorder (ADHD), which is present in a substantial subset of dyslexia diagnoses. Very few studies of balance in dyslexia have assessed ADHD symptoms, thereby motivating the hypothesis that such measures can account for the group differences observed. In this study, we assessed adults with dyslexia and similarly aged controls on a battery of cognitive, literacy and attention measures, alongside tasks of postural stability. Displacements of centre of mass to perturbations of posture were measured in four experimental conditions using digital optical motion capture. The largest group differences were obtained in conditions where cues to the support surface were reduced. Between-group differences in postural sway and in sway variability were largely accounted for by co-varying hyperactivity and inattention ratings, however. These results therefore suggest that postural instability in dyslexia is more strongly associated with symptoms of ADHD than to those specific to reading impairment.

Developmental Rate Of Immatures Of Two Fly Species Of Forensic Importance: Sarcophaga (liopygia) Ruficornis And Microcerella Halli (diptera: Sarcophagidae).

Since insect species are poikilothermic organisms, they generally exhibit different growth patterns depending on the temperature at which they develop. This factor is important in forensic entomology, especially for estimating postmortem interval (PMI) when it is based on the developmental time of the insects reared in decomposing bodies. This study aimed to estimate the rates of development, viability, and survival of immatures of Sarcophaga (Liopygia) ruficornis (Fabricius 1794) and Microcerella halli (Engel 1931) (Diptera: Sarcophagidae) reared in different temperatures: 10, 15, 20, 25, 30, and 35 ± 1 °C. Bovine raw ground meat was offered as food for all experimental groups, each consisting of four replicates, in the proportion of 2 g/larva. To measure the evolution of growth, ten specimens of each group were randomly chosen and weighed every 12 h, from initial feeding larva to pupae, and then discarded. Considering the records of weight gain, survival rates, and stability of growth rates, the range of optimum temperature for the development of S. (L.) ruficornis is between 20 and 35 °C, and that of M. halli is between 20 and 25 °C. For both species, the longest times of development were in the lowest temperatures. The survival rate at extreme temperatures (10 and 35 °C) was lower in both species. Biological data such as the ones obtained in this study are of great importance to achieve a more accurate estimate of the PMI.

Apoplastic And Intracellular Plant Sugars Regulate Developmental Transitions In Witches' Broom Disease Of Cacao.

Witches' broom disease (WBD) of cacao differs from other typical hemibiotrophic plant diseases by its unusually long biotrophic phase. Plant carbon sources have been proposed to regulate WBD developmental transitions; however, nothing is known about their availability at the plant-fungus interface, the apoplastic fluid of cacao. Data are provided supporting a role for the dynamics of soluble carbon in the apoplastic fluid in prompting the end of the biotrophic phase of infection. Carbon depletion and the consequent fungal sensing of starvation were identified as key signalling factors at the apoplast. MpNEP2, a fungal effector of host necrosis, was found to be up-regulated in an autophagic-like response to carbon starvation in vitro. In addition, the in vivo artificial manipulation of carbon availability in the apoplastic fluid considerably modulated both its expression and plant necrosis rate. Strikingly, infected cacao tissues accumulated intracellular hexoses, and showed stunted photosynthesis and the up-regulation of senescence markers immediately prior to the transition to the necrotrophic phase. These opposite findings of carbon depletion and accumulation in different host cell compartments are discussed within the frame of WBD development. A model is suggested to explain phase transition as a synergic outcome of fungal-related factors released upon sensing of extracellular carbon starvation, and an early senescence of infected tissues probably triggered by intracellular sugar accumulation.

Letter To The Editor: Atlantoaxial Instability And Chiari Malformation.

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Prediction of good glass formers in the Al-Ni-La and Al-Ni-Gd systems using topological instability and electronegativity

A new criterion has been recently proposed combining the topological instability (lambda criterion) and the average electronegativity difference (Delta e) among the elements of an alloy to predict and select new glass-forming compositions. In the present work, this criterion (lambda.Delta e) is applied to the Al-Ni-La and Al-Ni-Gd ternary systems and its predictability is validated using literature data for both systems and additionally, using own experimental data for the Al-La-Ni system. The compositions with a high lambda.Delta e value found in each ternary system exhibit a very good correlation with the glass-forming ability of different alloys as indicated by their supercooled liquid regions (Delta T(x)) and their critical casting thicknesses. In the case of the Al-La-Ni system, the alloy with the largest lambda.Delta e value, La(56)Al(26.5)Ni(17.5), exhibits the highest glass-forming ability verified for this system. Therefore, the combined lambda.Delta e criterion is a simple and efficient tool to select new glass-forming compositions in Al-Ni-RE systems. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3563099]

Convergence of developmental mutants into a single tomato model system: 'Micro-Tom' as an effective toolkit for plant development research

Background: The tomato (Solanum lycopersicum L.) plant is both an economically important food crop and an ideal dicot model to investigate various physiological phenomena not possible in Arabidopsis thaliana. Due to the great diversity of tomato cultivars used by the research community, it is often difficult to reliably compare phenotypes. The lack of tomato developmental mutants in a single genetic background prevents the stacking of mutations to facilitate analysis of double and multiple mutants, often required for elucidating developmental pathways. Results: We took advantage of the small size and rapid life cycle of the tomato cultivar Micro-Tom (MT) to create near-isogenic lines (NILs) by introgressing a suite of hormonal and photomorphogenetic mutations (altered sensitivity or endogenous levels of auxin, ethylene, abscisic acid, gibberellin, brassinosteroid, and light response) into this genetic background. To demonstrate the usefulness of this collection, we compared developmental traits between the produced NILs. All expected mutant phenotypes were expressed in the NILs. We also created NILs harboring the wild type alleles for dwarf, self-pruning and uniform fruit, which are mutations characteristic of MT. This amplified both the applications of the mutant collection presented here and of MT as a genetic model system. Conclusions: The community resource presented here is a useful toolkit for plant research, particularly for future studies in plant development, which will require the simultaneous observation of the effect of various hormones, signaling pathways and crosstalk.

Ring chromosome instability evaluation in six patients with autosomal rings

Ring chromosomes are often associated with abnormal phenotypes due to loss of genomic material and also because of ring instability at mitosis after sister chromatid exchange events. We investigated ring chromosome instability in six patients with ring chromosomes 4, 14, 15, and 18 by examining 48- and 72-h lymphocyte cultures at the first, second and subsequent cell divisions after bromodeoxyuridine incorporation. Although most cells from all patients showed only one monocentric ring chromosome, ring chromosome loss and secondary aberrations were observed both in 48-and 72-h lymphocyte cultures and in metaphase cells of the different cell generations. We found no clear-cut correlation between ring size and ring instability; we also did not find differences between apparently complete rings and rings with genetic material loss. The cytogenetic findings revealed secondary aberrations in all ring chromosome patients. We concluded that cells with ring chromosome instability can multiply and survive in vivo, and that they can influence the patient's phenotype.