Enzyme Variability in the Drosophila willistoni Group, I. Genetic Differentiation Among Sibling Species

We have studied by gel electrophoresis the variability of 14 structural genes in four sibling species, Drosophila willistoni, D. paulistorum, D. equinoxialis, and D. tropicalis. Samples of about 30 populations from different parts of the distribution areas of each species were examined. Genetic variants are found at every locus; 67% of the loci are polymorphic, having two or more alleles, the rarer of which has a frequency of 5% or higher.The gene frequencies are fairly uniform over the distribution area of each species, but considerably different in different species. It is estimated that individuals which belong to the different species differ on the average in somewhat more than one half of their gene loci. The morphological similarity of the four sibling species contrasts with the extensive diversity in their genetic materials.     

Genetic Differentiation Within and Between Species of the Drosophila willistoni Group

We describe allelic variation at 28 loci in six Caribbean populations of four sympatric species of Drosophila. Within any one species the allelic frequencies are very similar from population to population, although there is evidence of local as well as regional genetic differentiation. The genetic distance is greater between populations from different islands than between populations of the same island. When the allelic frequencies are compared between different species, a remarkable pattern appears. In any pair of species nearly half of the loci have essentially identical allelic frequencies, while nearly the other half of the loci have different alleles and in different frequencies. The loci with nearly identical allelic frequencies are different when different pairs of species are compared. The patterns of allelic variation within and between species are inconsistent with the hypothesis that the variation is adaptively neutral. Migration or mutation cannot explain the patterns of genetic variation, either. Balancing natural selection is the main process maintaining protein polymorphisms in natural populations.     

Sibling birthweight as a predictor of macrosomia in women with type 1 diabetes

Aims/hypothesis The aim of this study was to establish the value of maternal HbA₁c levels and older sibling birthweight as predictors of birthweight and macrosomia in the offspring of women with type 1 diabetes.Subjects and methods A total of 214 pregnancies of 107 women with type 1 diabetes were studied. Regression analysis was performed to test the predictive value of the birthweight of the first-born infant, HbA₁c levels, maternal BMI, maternal age and time between subsequent births on the birthweight of the second-born infant. Birthweights were corrected for sex and gestational age. The percentages of first- and second-born infants with macrosomia (weight >90th centile) were calculated and compared.Results Only the birthweight of earlier born infants was significantly related to that of second-born infants (p<0.001) and 40–50% of the variation in the birthweight of second-born infants could be explained by the birthweight of the first-born infants. About 85% of the mothers who gave birth to a macrosomic infant had a macrosomic infant in a subsequent pregnancy.Conclusions/interpretation Although it is clear that glycaemic control contributes to birthweight in women with type 1 diabetes, the birthweight of an earlier born infant appears to be a much better predictor of the birthweight of a subsequent infant than HbA₁c levels during pregnancy. It may, therefore, be used to identify patients at risk of giving birth to a macrosomic infant. Daily home monitoring of glucose levels, rather than HbA₁c levels, should be used for assessment of maternal glycaemia during pregnancy.     

Ethological Isolation Among Three Species of the planitibia Subgroup of Hawaiian Drosophila

Drosophila heteroneura and D. silvestris are sympatric species living on the island of Hawaii, while D. planitibia is allopatric on the nearby island of Maui. A pronounced ethological isolation is found between the sympatric species, and none between allopatric ones, except that D. planitibia females discriminate against D. heteroneura males. Male hybrids are sterile in allopatric crosses but fertile in sympatric ones. The ethological isolation and the hybrid sterility are uncorrelated. This is expected if premating isolation between closely related species is an ad hoc product of natural selection, while postmating isolation is an incidental result of genetic divergence. Some exceptions to the rule are discussed.     

血脂代谢紊乱作为心肌梗塞同胞对患病危险因素的相关研究

目的     

Calcium waves occur as Drosophila oocytes activate

Egg activation is the process by which a mature oocyte becomes capable of supporting embryo development. In vertebrates and echinoderms, activation is induced by fertilization. Molecules introduced into the egg by the sperm trigger progressive release of intracellular calcium stores in the oocyte. Calcium wave(s) spread through the oocyte and induce completion of meiosis, new macromolecular synthesis, and modification of the vitelline envelope to prevent polyspermy. However, arthropod eggs activate without fertilization: in the insects examined, eggs activate as they move through the female’s reproductive tract. Here, we show that a calcium wave is, nevertheless, characteristic of egg activation in Drosophila. This calcium rise requires influx of calcium from the external environment and is induced as the egg is ovulated. Pressure on the oocyte (or swelling by the oocyte) can induce a calcium rise through the action of mechanosensitive ion channels. Visualization of calcium fluxes in activating eggs in oviducts shows a wave of increased calcium initiating at one or both oocyte poles and spreading across the oocyte. In vitro, waves also spread inward from oocyte pole(s). Wave propagation requires the IP3 system. Thus, although a fertilizing sperm is not necessary for egg activation in Drosophila, the characteristic of increased cytosolic calcium levels spreading through the egg is conserved. Because many downstream signaling effectors are conserved in Drosophila, this system offers the unique perspective of egg activation events due solely to maternal components.The oocyte is unlike any cell type in the body. This highly specialized cell, once fertilized, will become totipotent, yet in many organisms the oocyte must remain developmentally arrested for years. The resting oocyte within the ovary is filled with maternally provided stores of mRNAs and proteins that will drive embryogenesis before zygotic genome activation, its cell cycle is stalled in a species-specific stage of meiosis (typically metaphase I or II), and its vitelline membrane is amenable to penetration by sperm and small molecules (1, 2). The mature oocyte remains in such a state until it is ready to be ovulated and fertilized. This quiescence period ranges from days in fruit flies to decades in humans.The series of events that leads to actualization of the oocyte’s developmental potential is collectively termed “egg activation.” In the vertebrates and echinoderms in which it has been most intensively studied, activation is sparked by a rise in cytosolic Ca²⁺ levels that is triggered by the fertilizing sperm (3–5). Depending on the organism, this Ca²⁺ rise sweeps through the egg in a single wave or in multiple oscillations, but in all cases the outcome is the same: meiosis resumes, the vitelline envelope is restructured, and mRNA and protein pools undergo modifications and turnover (6, 7). Evidence from other organisms such as mice and frogs indicates that the rise in Ca²⁺ likely starts a signaling cascade through calcium-dependent kinases and phosphatases such as CaMKII and calcineurin, which may have myriad effects on downstream pathway components to produce all of the hallmarks of egg activation (8, 9).Ca²⁺ transients were originally identified in medaka, where it was initially hypothesized that free Ca²⁺ from the external environment enters the oocyte with the fertilizing sperm, and calcium-induced calcium release from endoplasmic reticulum (ER) stores propagates the wave across the egg (10, 11). In teleost fish, extracellular Ca²⁺ can be sufficient, but not always necessary, to induce egg activation in vitro (e.g., zebrafish) (12, 13), but in many cases activation in vivo requires fertilization. In organisms in which the fertilizing sperm induces egg activation, the sperm either introduces a specific isoform of phospholipase C (PLC) (as in mice) (14), or sperm binding activates a Src-family kinase and in turn activates PLC (as in echinoderms) (15). Active PLC induces phosphoinositide signaling and ultimately results in release of Ca²⁺ from stores in the egg’s ER (14, 16). However, in the arthropods that have been examined, egg activation occurs independently of fertilization: in Drosophila melanogaster fruit flies (17) and Pimpla turionellae wasps (18), eggs activate as they move through the female’s reproductive tract, and Sicyonia shrimp eggs activate upon spawning into sea water (19). In addition, parthenogenetically reproducing organisms do not require sperm for egg activation to occur.That the insects tested thus far do not require fertilization for egg activation allows the study of egg activation events independent of the presence of sperm and thus of the initiation of zygote development. For example, this permitted experiments in Drosophila that showed that maternal functions that permit remodeling of the sperm nucleus into a male pronucleus are triggered by egg activation, not by fertilization (20). However, despite the difference in initial trigger, the downstream events of egg activation (resumption of meiosis, translation of new proteins from stored maternal RNAs, destabilization of selected maternal mRNAs, and changes in the egg’s coverings) occur in arthropods as well as in mammals (17, 21–24), and the changes that occur during Drosophila egg activation are signaled through many of the same pathways and components as in other organisms. For example, the requirement for calcineurin (20, 25–27), likely involved in the initial transmission of the calcium signal, characterizes egg activation in Xenopus as well as in Drosophila, and the activities of CDC20 (Drosophila cortex) in meiotic resumption (28), GLD-2 (Drosophila wispy) in cytoplasmic polyadenylation (29–32), and MAPK in signal transduction (33, 34) are conserved in Drosophila and other animals. Furthermore, phosphomodulation of proteins occurs during egg activation in the two organisms examined to date [sea urchin (4) and Drosophila (35)] and ∼80% of the phosphomodulated proteins in Drosophila are conserved across species, which may indicate a conserved phenomenon at egg activation (35). This conservation of “downstream” egg activation events raises the question of what triggers this process in organisms like Drosophila where sperm are not needed for egg activation and how this compares to events in sperm-activated systems. Ultimately, we aim to use the powerful tools available for Drosophila to genetically define the pathways governing this process.We previously showed that activation of Drosophila oocytes is triggered during the process of ovulation (passage of an oocyte from the ovary into the oviducts) (17) and could be accelerated by application of pressure. However, the immediate consequence of this on the oocyte was unknown. Our finding that calcineurin regulation is essential for egg activation (20, 25–27) and that Drosophila egg activation requires Ca²⁺ in the extracellular environment as well as the activity of mechanosensitive ion channels (36) suggests that a calcium flux might occur during activation of Drosophila eggs despite the different trigger.Here, using transgenic lines carrying a genetically encoded Ca²⁺ sensor (GCaMP3) expressed in the female germline, we discovered that intracellular calcium levels increase in the Drosophila oocyte as it is ovulated. The rise could be best visualized in vitro, where the calcium level increase initiates at one or both poles of the egg and sweeps through the egg cytoplasm. In vitro experiments show that the rise is triggered by mechanical pressure and requires the activity of ion channels in the egg’s plasma membrane. Although initiation of the Ca²⁺ wave requires external calcium [like some aspects of egg activation in mammals (3)], its propagation requires IP3-mediated release of internal Ca²⁺ stores.     

Species D Adenoviruses as Oncolytic Viral Vectors

Oncolytic adenoviruses (Ad) have shown promising results in the therapeutic treatment of cancer. Ad type 5 (Ad5) is the most extensively utilized Ad type. However, several limitations exist to using Ad5 as an oncolytic virus, including high levels of anti-Ad5 neutralizing antibodies in the population, binding of the Ad5 hexon to blood coagulation factor X leading to liver sequestration and toxicity, and reduced expression of the primary receptor CAR on many tumors. Here, we use in vitro methods to explore the oncolytic potential of four alternative Ad types (Ad26, 28, 45, and 48) belonging to the species D Ad subgroup and developed replication-competent species D Ads expressing the human sodium iodide symporter protein (hNIS) for combination radiovirotherapy. We evaluated the species D Ad vectors transduction, replication, cytotoxicity, and gene expression in six different cancer cell lines. Species D Ads showed the greatest transduction and cytotoxic killing in the SKBR3 breast cancer cells, followed by 293, A549, and HepG2 cells, however the cytotoxicity was less than the wild type Ad5 virus. In contrast, species D Ads showed limited transduction and cytotoxicity in the Hela and SKOV3 cancer cell lines. These species D Ad vectors also successfully expressed the hNIS gene during infection leading to increased iodide uptake in multiple cancer cell lines. These results, the low seroprevalence of anti-species D antibodies, and the lack of binding to blood coagulation FX, support further exploration of species D Ads as alternative oncolytic adenoviruses against multiple types of cancer.     

Reactive Oxygen Species as Mediators in Asthma

This review describes production and effects of reactive oxygen species (ROS) on airway function. ROS are important in many physiological processes but can also have detrimental effects on airway cells and tissues when produced in high quantities or during the absence of sufficient amounts of anti-oxidants. Therefore, these mediators play a prominent role in the pathogenesis of various inflammatory airway disorders, including asthma. Effects of ROS on airway function in asthma have been studied with isolated airway cells and tissues and with animal models and patients. With the use of inhibitors, transgenic animals and measurements of the release of ROS within the airways, it became clear that oxidative stress contributes to the initiation and worsening of inflammatory respiratory disorders.     

Drosophila as a model to study cardiac aging

With age, cardiac performance declines progressively and the risk of heart disease, a primary cause of mortality, rises dramatically. As the elderly population continues to increase, it is critical to gain a better understanding of the genetic influences and modulatory factors that impact cardiac aging. In an attempt to determine the relevance and utility of the Drosophila heart in unraveling the genetic mechanisms underlying cardiac aging, a variety of heart performance assays have recently been developed to quantify Drosophila heart performance that permit the use of the fruit fly to investigate the heart's decline with age. As for the human heart, Drosophila heart function also deteriorates with age. Notably, with progressive age the incidence of cardiac arrhythmias, myofibrillar disorganization and susceptibility to heart dysfunction and failure all increase significantly. We review here the evidence for an involvement of the insulin-TOR pathway, the K_ATP channel subunit dSur, the KCNQ potassium channel, as well as Dystrophin and Myosin in fly cardiac aging, and discuss the utility of the Drosophila heart model for cardiac aging studies.     

Mosquitoes of Anopheles hyrcanus (Diptera,Culicidae) Group: Species Diagnostic and Phylogenetic Relationships

Herein, we report the results of study of Anopheles species in Primorsk and Khabarovsk regions of Russia. Three species of the Anopheles hyrcanus group: An. kleini, An. pullus, and An. lesteri were identified by molecular taxonomic diagnostics for the first time in Russia. Surprisingly, An. sinensis, which earlier was considered the only species of Anopheles in Russian Far East, was not observed. We analyzed nucleotide variation in the 610-bp fragment of the 5′ end of the cytochrome c oxidase subunit I (COI) region. All species possessed a distinctive set of COI sequences. A maximum likelihood phylogenetic tree was constructed for members of the hyrcanus group. The examined Anopheles hyrcanus group members could be divided into two major subgroups: subgroup 1 (An. hyrcanus and An. pullus) and subgroup 2 (An. sinensis, An. kleini, and An. lesteri), which were found to be monophyletic.     

The Relevance of Spastic Esophageal Disorders as a Diagnostic Category

Purpose of Review

This review addresses the similarities and differences between the spastic esophageal disorders, including jackhammer esophagus, distal esophageal spasm (DES), and type III (spastic) achalasia. The pathophysiology, diagnosis, and treatment of each separate disorder are discussed herein, with an emphasis on overlapping and discordant features.

Recent Findings

The Chicago Classification is a hierarchical organizational scheme for esophageal motility disorders, currently in its third iteration, with direct impact on the definitions of these three disorders. Complementary diagnostic tools such as impedance planimetry and novel manometric parameters continue to evolve. The suite of potential treatments for these disorders is also expanding, with progressive interest in the role of peroral endoscopic myotomy alongside established pharmacologic and mechanical interventions.

Summary

Although jackhammer esophagus, distal esophageal spasm, and type III achalasia frequently overlap in terms of their clinical presentation and available management approaches, the divergences in their respective diagnostic criteria suggest that additional study may reveal additional mechanistic distinctions that lead in turn to further refinements in therapeutic decision-making.