Drosophila development,physiology, behavior,and lifespan are influenced by altered dietary composition

Diet profoundly influences the behavior of animals across many phyla. Despite this, most laboratories using model organisms, such as Drosophila, use multiple, different, commercial or custom-made media for rearing their animals. In addition to measuring growth, fecundity and longevity, we used several behavioral and physiological assays to determine if and how altering food media influence wild-type (Canton S) Drosophila melanogaster, at larval, pupal, and adult stages. Comparing 2 commonly used commercial food media we observed several key developmental and morphological differences. Third-instar larvae and pupae developmental timing, body weight and size, and even lifespan significantly differed between the 2 diets, and some of these differences persisted into adulthood. Diet was also found to produce significantly different thermal preference, locomotory capacity for geotaxis, feeding rates, and lower muscle response to hormonal stimulation. There were no differences, however, in adult thermal preferences, in the number or viability of eggs laid, or in olfactory learning and memory between the diets. We characterized the composition of the 2 diets and found particularly significant differences in cholesterol and (phospho)lipids between them. Notably, diacylglycerol (DAG) concentrations vary substantially between the 2 diets, and may contribute to key phenotypic differences, including lifespan. Overall, the data confirm that 2 different diets can profoundly influence the behavior, physiology, morphology and development of wild-type Drosophila, with greater behavioral and physiologic differences occurring during the larval stages.     

Characterization of development, behavior and neuromuscular physiology in the phorid fly, Megaselia scalaris

The Phoridae is known as 'scuttle flies' because they walk in rapid bursts of movement with short pauses between. In this study, larval locomotive behavior and development was characterized in the phorid, Megaselia scalaris. Comparison was made with the well-characterized fruit fly model, Drosophila melanogaster. Developmentally, the rate of maturation was consistently slower for Megaselia than Drosophila. This disparity was exaggerated at lower temperatures, particularly during larval development. In addition to slower growth, movements in Megaselia were also slower, as evidenced by reduced rates of larval body wall contractions and mouth hook movements. Megaselia larvae also displayed a unique behavior of swallowing air when exposed to a small pool of liquid. This permitted floating upon immersion and, therefore, might prevent drowning in the natural environment. The anatomical and physiological properties of a neuromuscular junction in the phorid larvae were also examined. The innervation of the motor nerve terminals on the ventral abdominal muscle (m6) is innervated by Type Ib and Is axons, similar to Drosophila. As in Drosophila, the Is terminals produce larger excitatory postsynaptic potentials (EPSPs) than the Ib. The amplitudes of the EPSPs in M. scalaris were reduced compared to those of D. melanogaster, but unlike D. melanogaster the EPSPs showed marked facilitation when stimulated with a 20 Hz train. We conclude that there may be differences in synaptic structure of the nerve terminals that could account for the different electrophysiological behaviors.     

Postnatal growth and behavioral development of mice cloned from adult cumulus cells

Since the first successful cloning of mammals from adult somatic cells, there has been no examination of the learning or behavior of cloned offspring. The possibility of adverse effects on animals produced through adult somatic cell cloning is high because many natural biological processes are bypassed and DNA from adult cells, which presumably contain mutations, are used. In this study, we compared cloned mice produced by microinjection transfer of cumulus cell nuclei into enucleated oocytes, to control mice that were specifically generated to eliminate confounding factors that are unique to our cloning procedure. Postnatal weight gain of clones was significantly greater than that of controls. Preweaning development observations revealed that first appearance or performance of 3 out of 10 measures was delayed in cloned mice; however, results of subsequent tests of learning and memory, activity level, and motor skills were comparable for both groups. Together, these data suggest that nuclear transfer of adult somatic cell nuclei to produce cloned mice may delay the appearance of a few developmental milestones but it does not adversely affect the overall postnatal behavior of mice. In addition, this procedure may cause late onset of significantly increased body weight in cloned offspring, the cause or causes of which are being further examined.     

Perinatal physiology in cloned and normal calves: hematologic and biochemical profiles

Although a majority of clones are born normal and apparently healthy, mortality rates of nearly 30% are described in many reports. Such losses are a major limitation of cloning technology and represent substantial economic investment as well as justifiable animal health and welfare concerns. Prospective, controlled studies are needed to understand fully the causes of neonatal mortality in clones and to develop preventive and therapeutic strategies to minimize losses. We report here the findings of studies on the hematologic and biochemical profiles of cloned and control calves in the immediate 48-h postpartum period. Cloned calves were similar to control calves for a majority of parameters studied including blood gases, concentrations of plasma proteins, minerals and electrolytes, and white blood cell, neutrophil, lymphocyte, and platelet counts. The most notable differences between clones and controls in this study were reduced red- and white-blood cell counts in clones at birth and 1 h of age. As a group, plasma electrolyte concentrations were more variable in clones, and the variability tended to be shifted either higher (sodium, chloride) or lower (potassium, bicarbonate) than in controls. Previously, we noted differences in carbohydrate parameters, the length of time required for clones to make the neonatal adaptation to life ex utero, and morphology of the cloned placenta. Taken together, our findings suggest that cloned calves experience greater difficulty adjusting to life ex utero and that further research is warranted to determine the nature of the relationship between the physiological differences noted here in clones at birth and concomitant abnormal placental morphology.     

Perinatal physiology in cloned and normal calves: physical and clinical characteristics

The period immediately after birth is a vital time for all newborn calves as the cardiovascular, respiratory, and other organ systems adapt to life ex utero. Reported neonatal mortality rates suggest this period to be especially critical in cloned calves; yet prospective, controlled studies on the physiological status of these calves are lacking. The objectives of this study were to compare neonatal (birth to 48 h of age) physical and clinical characteristics and placental morphology of cloned and embryo transfer control calves delivered by cesarean section after induced labor. All calves were raised under specialized neonatal-care protocols at a large-animal veterinary research and teaching hospital. Cloned calves were similar to controls for many parameters studied. Notable exceptions included developmental delays of important physical adjustment parameters and enlargement of the umbilical region. Placentas associated with cloned calves contained fewer total placentomes, a twofold increase in surface area and mass per placentome, and a shift in placentome morphology toward larger, flatter placentomes. The most striking clinical variations detected in clones were hypoglycemia and hyperfructosemia, both measures of carbohydrate metabolism. Because the placenta is known to be the source of plasma fructose in newborn calves, increased fructose production by the cloned placenta may be an important factor in the etiology of umbilical and cardiac anomalies in clones observed in this and other studies.     

GABA transporters inDrosophila melanogaster: molecular cloning, behavior, and physiology

Molecular cloning of GABA transporter-homologous cDNAs from aDrosophila melanogaster headspecific library was accomplished using a conserved oligomer from a highly conserved domain within the mammalian GABA transporters. Partial DNA sequencing of these cDNAs demonstrated homology with the mammalian transporters, indicating these are ancient, evolutionarily conserved molecules. Although theDrosophila cDNAs had distinct restriction enzyme patterns, they recognized the same locus inDrosophila genomic DNA, suggesting that the multiple isoforms might arise via alternative splicing. Antibodies specific for the mammalian GABA transporters GAT1, GAT2 and GAT3 recognized non-overlapping and developmentally distinct patterns of expression inDrosophila neuronal tissues. Treatment of larval instars with nipecotic acid, a generalized GABA reuptake inhibitor, revealed specific, dose-dependent alterations in behavior consistent with the presence of multiple transporter molecules with differing affinities for this drug. Synaptic current recordings revealed that nipecotic acid treated larvae have an increase in latency jitter of evoked quantal release, resulting in a broader average excitatory junctional current which was manifested in a broader EJP. These results imply that alterations in the development of the CNS occur if GABAergic neurotransmission is protentiated during development. The data suggest that, as in mammals, there are multiple GABA transporters inDrosophila whose expression is differentially regulated.     

Effects of donor oocytes and culture conditions on development of cloned mice embryos

Mice have been successfully cloned from somatic and embryonic stem (ES) cells using the "Honolulu method." In the present study, different donor oocytes and different culture conditions were compared to evaluate the developmental potential of nuclear transfer embryos reconstructed with an inbred ES cell line HM-1. Oocytes were recovered from two different F1 donors B6D2F1 (C57BL/6 x DBA/2) and B6CBAF1 (C57BL/6 x CBA). There was no effect of oocyte origin on development of cloned embryos to the morulae/blastocyst stage (B6D2F1 44.1% vs. B6CBAF1 45.0%), and the transferred embryos could develop to term. Two culture conditions were compared to show their ability to support development to the morulae/blastocyst stage of reconstructed embryos with B6D2F1 oocytes. The total cell number in the cloned blastocysts cultured in M16 with 20% oxygen was much higher than that observed in CZB with 20% oxygen. Low oxygen concentration during culture of nuclear transfer embryos in CZB medium showed no beneficial effect on pre-implantation development, no embryos developed to term after transfer to surrogate mothers. Our results demonstrated that not only B6D2F1, but B6CBAF1 oocytes, can be used for nuclear transfer. M16 medium is superior for culture of nuclear transfer embryos and low oxygen concentration with CZB medium during culture shows no benefit on development of cloned embryos.     

Ecoimmunology and microbial ecology: Contributions to avian behavior,physiology, and life history

Bacteria have had a fundamental impact on vertebrate evolution not only by affecting the evolution of the immune system, but also generating complex interactions with behavior and physiology. Advances in molecular techniques have started to reveal the intricate ways in which bacteria and vertebrates have coevolved. Here, we focus on birds as an example system for understanding the fundamental impact bacteria have had on the evolution of avian immune defenses, behavior, physiology, reproduction and life histories. The avian egg has multiple characteristics that have evolved to enable effective defense against pathogenic attack. Microbial risk of pathogenic infection is hypothesized to vary with life stage, with early life risk being maximal at either hatching or fledging. For adult birds, microbial infection risk is also proposed to vary with habitat and life stage, with molt inducing a period of increased vulnerability. Bacteria not only play an important role in shaping the immune system as well as trade-offs with other physiological systems, but also for determining digestive efficiency and nutrient uptake. The relevance of avian microbiomes for avian ecology, physiology and behavior is highly topical and will likely impact on our understanding of avian welfare, conservation, captive breeding as well as for our understanding of the nature of host-microbe coevolution.     

Hemichannels: permeants and their effect on development, physiology and death

Hemichannels, which are one half of the gap junction channels, have independent physiological roles. Although hemichannels consisting of connexins are more widely documented, hemichannels of pannexins, proteins homologous to invertebrate gap junction proteins also have been studied. There are at least 21 different connexin and three pannexin isotypes. This variety in isotypes results in tissue-specific hemichannels, which have been implicated in varied events ranging from development, cell survival, to cell death. Hemichannel function varies with its spatio-temporal opening, thus demanding a refined degree of regulation. This review discusses the activity of hemichannels and the molecules released in different physiological states and their impact on tissue functioning.     

Integrin-mediated regulation of neurovascular development,physiology and disease

The mammalian central nervous system (CNS) is comprised of billions of neurons and glia that are intertwined with an elaborate network of blood vessels. These various neural and vascular cell types actively converse with one another to form integrated, multifunctional complexes, termed neurovascular units. Cell-cell communication within neurovascular units promotes normal CNS development and homeostasis, and abnormal regulation of these events leads to a variety of debilitating CNS diseases. This review will summarize (i) cellular and molecular mechanisms that regulate physiological assembly and maintenance of neurovascular units; and (ii) signaling events that induce pathological alterations in neurovascular unit formation and function. An emphasis will be placed on neural-vascular cell adhesion events mediated by integrins and their extracellular matrix (ECM) ligands. I will highlight the role of a specific adhesion and signaling axis involving αvβ8 integrin, latent transforming growth factor β’s (TGFβ’s), and canonical TGFβ receptors. Possible functional links between components of this axis and other signal transduction cascades implicated in neurovascular development and disease will be discussed. In summary, comprehensively understanding the pathways that regulate bidirectional neural-vascular cell contact and communication will provide new insights into the mechanisms of neurovascular unit development, physiology and disease.     

Integrin-mediated regulation of neurovascular development,physiology and disease

The mammalian central nervous system (CNS) is comprised of billions of neurons and glia that are intertwined with an elaborate network of blood vessels. These various neural and vascular cell types actively converse with one another to form integrated, multifunctional complexes, termed neurovascular units. Cell-cell communication within neurovascular units promotes normal CNS development and homeostasis, and abnormal regulation of these events leads to a variety of debilitating CNS diseases. This review will summarize (1) cellular and molecular mechanisms that regulate physiological assembly and maintenance of neurovascular units; and (2) signaling events that induce pathological alterations in neurovascular unit formation and function. An emphasis will be placed on neural-vascular cell adhesion events mediated by integrins and their extracellular matrix (ECM) ligands. I will highlight the role of a specific adhesion and signaling axis involving αvβ8 integrin, latent transforming growth factor β''s (TGFβ''s), and canonical TGFβ receptors. Possible functional links between components of this axis and other signal transduction cascades implicated in neurovascular development and disease will be discussed. Comprehensively understanding the pathways that regulate bidirectional neural-vascular cell contact and communication will provide new insights into the mechanisms of neurovascular unit development, physiology and disease.Key words: αvβ8 integrin, latent TGFβ, neurovascular unit, brain angiogenesis, cerebral hemorrhage     

Histone lysine demethylases: emerging roles in development, physiology and disease

The discovery of an increasing number of histone demethylases has highlighted the dynamic nature of the regulation of histone methylation, a key chromatin modification that is involved in eukaryotic genome and gene regulation. A flurry of recent studies has offered glimpses into the specific biological roles of these enzymes and their potential connections to human diseases. These advances have also catalysed a resurgence of interest in epigenetic regulators as potential therapeutic targets.