Comparison of population genetic estimates amongst wild,F1 and F2 cultured abalone (Haliotis midae)

Haliotis midae is South Africa's most important aquaculture species. The reproduction cycle is currently not closed as many farms rely on wild‐caught broodstock for seed production. However, there is an increasing interest in genetic improvement in commercial stocks, with a growing number of producers implementing selective breeding strategies. High throughput commercial production and mass spawning make it difficult to maintain breeding records; therefore, mostly mass selection is practised. The high fecundity and unequal parental contributions also often lead to increased levels of inbreeding. This study therefore aimed to assess the genetic effects of such breeding practices on commercial populations of H. midae. Using microsatellite loci, the genetic properties of a wild, an F1 and an F2 population were estimated and compared. Although there was no significant loss of genetic diversity amongst the cultured populations in comparison with the wild progenitor population, there was low‐to‐moderate genetic differentiation between populations. Relatedness amongst the F2 population was significant, and the rate of inbreeding was high. The effective population size for the F2 (±50) was also comparatively small with respect to the wild (∞) and F1 (±470) populations. These results suggest that farms need to give caution to breeding practices beyond the first (F1) generation and aim to increase effective population sizes and minimise inbreeding to ensure long‐term genetic gain and productivity. This study also confirms the usefulness of population genetic analyses for commercial breeding and stock management in the absence of extensive pedigree records.     

The hinged back plate mechanism in glassy wax tests of New Zealand male soft scale insects (Hemiptera: Coccoidea: Coccidae)

Male scale insects (Hemiptera: Coccoidea) undergo a metamorphosis of the neometabola type, from scale-like nymph through prepupa and pupa to winged adult. The nymphal instar before prepupa secretes a waxy protective covering that remains in place throughout metamorphosis and these covers are characteristic of each family of scale insects. Most scale insect families (e.g. mealybugs, eriococcids, diaspidids) have rather loosely woven male covers, but male nymphs in the family Coccidae (soft scales) construct more rigid, glassy wax tests, which need a special mechanism for adult emergence. In the New Zealand male soft scales, a suture across the posterior quarter of the test enables the back plate to flex at a pair of hinges, to be raised up off the substrate, and so allow egress. The waxy back plate hinges are secreted by groups of tubular ducts on the abdominal dorsum of 2nd-instar males, during construction of the test. Scanning electron micrographs (SEMs) show the detail and diversity of hinge types. The wax tests of most New Zealand Coccidae, both female and male, are apparently unique in that they are constructed in rows of hexagonal plates, separated by sutures, however in the male test, the sutures are all fused except for the back plate suture. The two species in the endemic New Zealand genus Pounamococcus have male tests more like those of species in the Australian genus Austrolecanium.     

Deletion of Tumor Necrosis Factor-�� Receptor 1 (TNFR1) Protects against Diet-induced Obesity by Means of Increased Thermogenesis

In diet-induced obesity, hypothalamic and systemic inflammatory factors trigger intracellular mechanisms that lead to resistance to the main adipostatic hormones, leptin and insulin. Tumor necrosis factor-α (TNF-α) is one of the main inflammatory factors produced during this process and its mechanistic role as an inducer of leptin and insulin resistance has been widely investigated. Most of TNF-α inflammatory signals are delivered by TNF receptor 1 (R1); however, the role played by this receptor in the context of obesity-associated inflammation is not completely known. Here, we show that TNFR1 knock-out (TNFR1 KO) mice are protected from diet-induced obesity due to increased thermogenesis. Under standard rodent chow or a high-fat diet, TNFR1 KO gain significantly less body mass despite increased caloric intake. Visceral adiposity and mean adipocyte diameter are reduced and blood concentrations of insulin and leptin are lower. Protection from hypothalamic leptin resistance is evidenced by increased leptin-induced suppression of food intake and preserved activation of leptin signal transduction through JAK2, STAT3, and FOXO1. Under the high-fat diet, TNFR1 KO mice present a significantly increased expression of the thermogenesis-related neurotransmitter, TRH. Further evidence of increased thermogenesis includes increased O₂ consumption in respirometry measurements, increased expressions of UCP1 and UCP3 in brown adipose tissue and skeletal muscle, respectively, and increased O₂ consumption by isolated skeletal muscle fiber mitochondria. This demonstrates that TNF-α signaling through TNFR1 is an important mechanism involved in obesity-associated defective thermogenesis.     

Leaf morphological responses to variation in water availability for plants in the <Emphasis Type="Italic">Piriqueta caroliniana</Emphasis> complex

Distribution of plants and the expression of traits associated with environmental variation can be affected by both average conditions and the variance in conditions including extreme climatic events. We expect that these same factors should affect the distribution of plants in hybrid zones between ecologically distinct species where the hybrids should occupy ecotones or intermediate habitats. We evaluated water availability and leaf morphological differences among parental and hybrid populations of herbaceous perennial plants in the Piriqueta caroliniana complex along environmental gradients in Southeastern North America. We focus on two taxa in this group; the viridis morphotype, which occurs in southern Florida, and the caroliniana morphotype, which is distributed from northern Florida to southern Georgia. Advanced-generation hybrid derivatives of these morphotypes occupy a broad geographic region that extends across much of central Florida. Overall, we found that hybrid populations occurred in significantly drier locations, indicating that their habitat requirements are transgressive (i.e., exceeding parental values) rather than intermediate to the parental morphotypes. Water availability differed between the two sampling years, and plants displayed morphological changes in response to these changes in moisture. During the drier year, leaves were narrower and more hirsute, corroborating experimental results that these leaf traits are plastic, and confirming that plasticity occurs in natural habitats. Hybrids exhibited intermediate leaf traits (shape and size) across both years, and displayed transgressive (hair density) leaf traits during the drier year. The apparent canalization of the hybrids’ leaf morphological traits may contribute to their tolerance of variable environmental conditions and may partially explain why they have displaced the caroliniana morphotype in central Florida.     

Robust protein quantitation in chromatographic fractions using MALDI-MS of tryptic peptides

A method is introduced to evaluate protein concentrations using the height sum of all MALDI-MS peaks that unambiguously match theoretic tryptic peptide masses of the protein sought after. The method uses native chromatographic protein fractionation prior to digestion but does not require any depletion, labeling, derivatization, or preparation of a compound similar to the analyte. All peak heights of tryptic peptides are normalized with the peak height of a unique standard peptide added to the MALDI-MS samples. The sum of normalized peak heights, S(n), or the normalized mean peak height, M(n), reflects the concentration of the respective protein. For fractions containing various proteins, S(n) and M(n) can be used to compare concentrations of a protein between different fractions. For fractions with one predominating protein, they can be used to estimate concentration ratios between fractions, or to quantify the fractional protein concentration after calibration with pure protein solutions. Initial native fractionation retains the possibility to apply all conventional analytic procedures. Moreover, it renders the method relatively robust to MS mass accuracy. The method was validated with albumin, transferrin, alpha1-antitrypsin, and immunoglobulin G within highly complex chromatographic fractions of pathological and normal sera, which contained the respective intact native protein in dominating as well as minor concentrations. The correlation found between S(n) and the protein concentration as determined with ELISA showed that the method can be applied to select markers for distinguishing between normal and pathological serum samples.     

Effects of dietary protein to carbohydrate balance on energy intake,fat storage,and heat production in mice

Objective:

Protein leverage plays a role in driving increased energy intakes that may promote weight gain. The influence of the protein to carbohydrate ratio (P:C) in diets of C57BL/6J mice on total energy intake, fat storage, and thermogenesis was investigated.

Design and Methods:

Male mice (9 weeks old) were provided ad libitum access to one of five isocaloric diets that differed in P:C. Food intake was recorded for 12 weeks. After 16 weeks, white adipose tissue (WAT) and brown adipose tissue (BAT) deposits were dissected, weighed, and the expression levels of key metabolic regulators were determined in BAT. In a separate cohort, body surface temperature was measured in response to 25 diets differing in protein, fat, and carbohydrate content.

Results:

Mice on low P:C diets (9:72 and 17:64) had greater total energy intake and increased WAT and BAT stores. Body surface temperature increased with total energy intake and with protein, fat, and carbohydrate, making similar contributions per kJ ingested. Expression of three key regulators of thermogenesis were downregulated in BAT in mice on the lowest P:C diet.

Conclusions:

Low‐protein diets induced sustained hyperphagia and a generalized expansion of fat stores. Increased body surface temperature on low P:C diets was consistent with diet‐induced thermogenesis (DIT) as a means to dissipate excess ingested energy on such diets, although this was not sufficient to prevent development of increased adiposity. Whether BAT was involved in DIT is not clear. Increased BAT mass on low P:C diets might suggest so, but patterns of thermogenic gene expression do not support a role for BAT in DIT, although they might reflect failure of thermogenic function with prolonged exposure to a low P:C diet.     

Force communication in multicellular tissues addressed by laser nanosurgery

Cell contractility is a prominent mechanism driving multicellular tissue development and remodeling. Forces originated by the actomyosin cytoskeleton not only act within the cell body but can also propagate many layers away from the contraction source and grant tissues the ability to organize collectively and to achieve robust remodeling through development. Tissue tension is being thoroughly investigated in model organisms and increasing evidence is revealing the major role played by the communication, dynamics and propagation of cell-to-cell physical forces in multicellular remodeling. Recently, pulsed-laser-based surgery has fostered in vivo experimental studies to investigate intracellular and supracellular forces in action. The technique offers a unique method to perturb mechanical equilibrium in a subpopulation of cells or in a single cell, while the overall tissue remains intact. In particular, improved ablation precision with short laser pulses and the combination of this technique with biophysical models now allow an in-depth understanding of the role of cellular mechanics in tissue morphogenesis. We first characterize laser ablation modes available to perform intracellular, cellular, or multi-cellular ablation via the example of the model monolayer tissue of the amnioserosa of Drosophila by relating subnanosecond laser pulse energy to ablation efficiency and the probability of cavitation bubble formation. We then review recent laser nanosurgery experiments that have been performed in cultured cells and that tackle actomyosin mechanics and provide molecular insights into force-sensing mechanisms. We finally review studies showing the central role of laser ablation in revealing the nature and orientation of forces involved in intracellular contractility and force mechanosensing in tissue development, e.g., axis elongation, branching morphogenesis, or tissue invagination. We discuss the perspectives offered by the technique in force-based cell-cell communication and mechanosensing pathways.     

Development of Left Ventricular Longitudinal Speckle Tracking Echocardiography in Very Low Birth Weight Infants with and without Bronchopulmonary Dysplasia during the Neonatal Period

Objectives

In preterm infants, postnatal myocardial adaptation may be complicated by bronchopulmonary dysplasia (BPD). We aimed to describe the development of left ventricular function by serial 2D, Doppler, and speckle tracking echocardiography (2D-STE) in infants with and without BPD during the neonatal period and compare these to anthropometric and conventional hemodynamic parameters.

Study Design

Prospective echocardiography on day of life (DOL) 1, 7, 14, and 28 in 119 preterm infants <1500 g birth weight of whom 36 developed BPD (need for oxygen supplementation at 36 weeks gestational age). Non-BPD and BPD infants differed significantly in median (IQR) gestational age (25.5(24–26.5) weeks vs. 29(27–30) weeks, p<0.001) and birth weight (661(552–871) g vs. 1100(890–1290) g, p<0.001).

Results

The intra- and inter-observer variability of the 2D-STE parameters measured did not depend on time of measurement, although there were significant differences in the reproducibility of the parameters. Low intra- and inter-observer variability was seen for longitudinal systolic strain and strain rate mid septum with a median CV (coefficient of variation) of <4.6%. Much higher CVs (>10%) were seen for the apical segment. While anthropometric parameters show rapid development during the first 4 weeks of life, the speckle tracking parameters did not differ statistically significantly during the neonatal period. Infants with and without BPD differed significantly (p<0.001) in the development of anthropometric parameters, conventional hemodynamic parameters except for heart rate, and 2D-STE parameters: global longitudinal systolic strain rate (GLSSR) and longitudinal systolic strain for the mid left wall (LSSR). The largest differences were seen at DOL 1 and 7 in GLSSR (p<0.001) and in LSSR (p<0.01).

Conclusions

Reproducible 2D-STE measurements are possible in preterm infants <1500 g. Cardiac deformation reveals early (DOL 1 and 7) ventricular changes (GLSSR and LSSR) in very low birth weight infants who develop BPD.