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Search Results: 1 - 10 of 213514 matches for " Jeffrey L.;Wolfner "
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The vitellogenin gene family of Aedes aegypti
Hamblin, Martha T.;Marx, Jeffrey L.;Wolfner, Mariana F.;Hagedorn, Henry H.;
Memórias do Instituto Oswaldo Cruz , 1987, DOI: 10.1590/S0074-02761987000700021
Abstract: we have been interested in identifying genes that play a role in reproduction of the mosquito aedes aegypti. our interests are currently focused on the vitellogenin genes which in the mosquito are expressed only in the fat body in response to the insect steroid hormone, 20-hydroxyecdysone. four of the five vitellogenin genes in the genome have been cloned. we have examined the relationships between these genes and find that they form a small gene family exhibiting different levels of relationship.
YA is needed for proper nuclear organization to transition between meiosis and mitosis in Drosophila
Katharine L Sackton, Jacqueline M Lopez, Cindy L Berman, Mariana F Wolfner
BMC Developmental Biology , 2009, DOI: 10.1186/1471-213x-9-43
Abstract: We find that meiosis is completed normally in the absence of YA function. The first defects in embryos and eggs from mutant mothers first appear just after the completion of meiosis, and are seen as abnormal associations among the resultant haploid nuclei. These defects are associated with asynchronies in the cell cycle-dependent chromatin condensation state of the haploid nuclei. However, we find evidence of DNA replication in the absence of YA function.Our data suggest YA function is needed at a control point, following meiosis II and the initiation of the first postmeiotic S phase, which is sensitive to the chromatin condensation state of the haploid meiotic products.Mature Drosophila oocytes are arrested in metaphase of meiosis I. To begin development, oocytes must undergo a number of changes that are collectively called egg activation [1-5]. The egg is hydrated, proteins in its vitelline membrane undergo cross-linking, certain maternal RNAs are polyadenylated and translated while others are degraded [6], the phosphorylation state of many proteins changes [7-9], the cortical actin cytoskeleton is reorganized [10], and meiosis resumes. Egg activation in Drosophila [1] and other insects [11-13], is independent of fertilization (in contrast to the situation in other animals) [14]; it is triggered instead by passage through the female's reproductive tract. Despite differences in trigger, the initial cause of egg activation in essentially all animals appears to be an increase in intracellular calcium [4,5,15]. Upon activation, Drosophila oocytes complete meiosis rapidly without cytokinesis, resulting in four haploid nuclei located near the membrane and aligned perpendicular to the long axis of the egg [16,17]. The chromosomes of all four meiotic products decondense and appear morphologically to be in a state similar to interphase [18]. In unfertilized, activated eggs, all four meiotic products synchronously replicate their DNA once, and then condense their chromosome
Precious Essences: Female Secretions Promote Sperm Storage in Drosophila
Mariana F. Wolfner
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1001191
Abstract: Sperm that females receive during mating are stored in special places in the females' reproductive tracts. These storage sites serve to support and retain the sperm, maintaining the sperms' motility and, in mammals, permitting final sperm-maturation. The molecules that attract sperm to these sites and mediate what happens to them there have remained elusive. New research, using elegant genetic tools in Drosophila, shows that secretory cells associated with a sperm storage organ are important in sperm-supportive functions. When females lack function of these cells, they do not store sperm, or the sperm that they do store lose motility. Intriguingly, these effects influence gametes beyond the secretory cells' immediate vicinity. Loss of these cells eliminates the motility of sperm stored elsewhere in the reproductive tract and prevents the movement of eggs through the tract to exit the female. As a result of the latter problem, fertilized eggs hatch inside female flies that lack these secretory cells: instead of laying eggs, these females can “give birth” to live offspring. Because the cellular source of these gamete-regulating substances is now known, future studies can identify the specific molecules and mechanisms by which a female attracts sperm into storage and regulates the movement of sperm and eggs within her reproductive tract. It will be fascinating to determine how these molecules and mechanisms maintain gametes in active and viable forms and how evolution can modulate this to result in diverse reproductive strategies. Identification of these molecules also has potential practical implications for strategies to regulate the reproduction of insects of medical or agricultural importance.
Precious Essences: Female Secretions Promote Sperm Storage in Drosophila
Mariana F. Wolfner
PLOS Biology , 2011, DOI: 10.1371/journal.pbio.1001191
Abstract: Sperm that females receive during mating are stored in special places in the females' reproductive tracts. These storage sites serve to support and retain the sperm, maintaining the sperms' motility and, in mammals, permitting final sperm-maturation. The molecules that attract sperm to these sites and mediate what happens to them there have remained elusive. New research, using elegant genetic tools in Drosophila, shows that secretory cells associated with a sperm storage organ are important in sperm-supportive functions. When females lack function of these cells, they do not store sperm, or the sperm that they do store lose motility. Intriguingly, these effects influence gametes beyond the secretory cells' immediate vicinity. Loss of these cells eliminates the motility of sperm stored elsewhere in the reproductive tract and prevents the movement of eggs through the tract to exit the female. As a result of the latter problem, fertilized eggs hatch inside female flies that lack these secretory cells: instead of laying eggs, these females can “give birth” to live offspring. Because the cellular source of these gamete-regulating substances is now known, future studies can identify the specific molecules and mechanisms by which a female attracts sperm into storage and regulates the movement of sperm and eggs within her reproductive tract. It will be fascinating to determine how these molecules and mechanisms maintain gametes in active and viable forms and how evolution can modulate this to result in diverse reproductive strategies. Identification of these molecules also has potential practical implications for strategies to regulate the reproduction of insects of medical or agricultural importance.
Evolutionary Rate Covariation Identifies New Members of a Protein Network Required for Drosophila melanogaster Female Post-Mating Responses
Geoffrey D. Findlay,Jessica L. Sitnik,Wenke Wang,Charles F. Aquadro,Nathan L. Clark,Mariana F. Wolfner
PLOS Genetics , 2014, DOI: doi/10.1371/journal.pgen.1004108
Abstract: Seminal fluid proteins transferred from males to females during copulation are required for full fertility and can exert dramatic effects on female physiology and behavior. In Drosophila melanogaster, the seminal protein sex peptide (SP) affects mated females by increasing egg production and decreasing receptivity to courtship. These behavioral changes persist for several days because SP binds to sperm that are stored in the female. SP is then gradually released, allowing it to interact with its female-expressed receptor. The binding of SP to sperm requires five additional seminal proteins, which act together in a network. Hundreds of uncharacterized male and female proteins have been identified in this species, but individually screening each protein for network function would present a logistical challenge. To prioritize the screening of these proteins for involvement in the SP network, we used a comparative genomic method to identify candidate proteins whose evolutionary rates across the Drosophila phylogeny co-vary with those of the SP network proteins. Subsequent functional testing of 18 co-varying candidates by RNA interference identified three male seminal proteins and three female reproductive tract proteins that are each required for the long-term persistence of SP responses in females. Molecular genetic analysis showed the three new male proteins are required for the transfer of other network proteins to females and for SP to become bound to sperm that are stored in mated females. The three female proteins, in contrast, act downstream of SP binding and sperm storage. These findings expand the number of seminal proteins required for SP's actions in the female and show that multiple female proteins are necessary for the SP response. Furthermore, our functional analyses demonstrate that evolutionary rate covariation is a valuable predictive tool for identifying candidate members of interacting protein networks.
Green Tea Polyphenols Mediated Apoptosis in Intestinal Epithelial Cells by a Fadd-Dependent Pathway  [PDF]
Helieh S. Oz, Jeffrey L. Ebersole
Journal of Cancer Therapy (JCT) , 2010, DOI: 10.4236/jct.2010.13018
Abstract: Colorectal cancer is the most common malignant complication in patients with chronic inflammatory bowel disease (IBD). In addition, these patients are at risk for developing painful complications during chemotherapy due to cytotoxic effects of drugs currently in use. Past studies have suggested a protective effect of tea consumption on gastrointestinal (GI) malignancies. Green tea polyphenols (GrTP) inhibited carcinogen-induced GI tumors in rodents and induced apoptosis in various carcinoma cell lines. We hypothesized that GrTP and its polyphenolic compounds regulate apoptosis in the intestinal epithelia. In this study, the effects of GrTP and its polyphenolics on apoptosis was evaluated in intestinal epithelial, IEC-6, cells grown to 85% confluency. GrTP (400-800 mg/ml) induced DNA fragmentation in a dose dependent fashion. Higher concentrations (> 800 mg/ml) induced a mixed apoptosis and cytolysis. Epithelial cells exposed to GrTP and a major polyphenol, EGCG, but not EGC or EC, increased caspase activities in a time and dose dependent manner. The caspase inhibitors rescued cells from GrTP and EGCG-induced cell death. Concomitantly, GrTP resulted in activation of fatty acid synthase (Fas)-associated protein with death domain (FADD) and recruitment to Fas/CD95 domain 30 minutes following treatment. While GrTP also blocked NF-?B activation, an NF-?B inhibitor (MG132) only promoted cytolysis. In conclusion, these data demonstrated GrTP and EGCG induced apoptosis in intestinal epithelia mediated by caspase-8 through a FADD dependent pathway. Future investigation may warrant preventive as well as therapeutic strategies for GrTP in GI malignancy.
Inhibitory roles of protein kinase B and peroxisome proliferator-activated receptor gamma coactivator on hepatic HMG-CoA reductase promoter activity  [PDF]
Gene C. Ness, Jeffrey L. Edelman
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.410A3001
Abstract:

Since we had previously demonstrated that siRNAs to tristetraprolin (TTP) markedly inhibited insulin stimulation of hepatic HMG-CoA reductase (HMGR) transcription, we investigated the effects of transfecting rat liver with TTP constructs. We found that transfecting diabetic rats with TTP did not increase HMGR transcription but rather led to modest inhibition. We then investigated whether co-transfection with protein kinase B, hepatic form (AKT2), might lead to phosphorylation and result in activation of HMGR transcription. We found that this treatment resulted in near complete inhibition of transcription. Transfection with peroxisome proliferator-activated receptor g coactivator (PGC-1a) also inhibited HMGR transcription. These results show that although TTP is needed for activation of HMGR transcription, it cannot by itself activate this process. AKT2 and PGC-1a, which mediate the activation of gluconeogenic genes by insulin, exert the opposite effect on HMGR.

Sustained Post-Mating Response in Drosophila melanogaster Requires Multiple Seminal Fluid Proteins
K. Ravi Ram,Mariana F Wolfner
PLOS Genetics , 2007, DOI: 10.1371/journal.pgen.0030238
Abstract: Successful reproduction is critical to pass genes to the next generation. Seminal proteins contribute to important reproductive processes that lead to fertilization in species ranging from insects to mammals. In Drosophila, the male's accessory gland is a source of seminal fluid proteins that affect the reproductive output of males and females by altering female post-mating behavior and physiology. Protein classes found in the seminal fluid of Drosophila are similar to those of other organisms, including mammals. By using RNA interference (RNAi) to knock down levels of individual accessory gland proteins (Acps), we investigated the role of 25 Acps in mediating three post-mating female responses: egg production, receptivity to remating and storage of sperm. We detected roles for five Acps in these post-mating responses. CG33943 is required for full stimulation of egg production on the first day after mating. Four other Acps (CG1652, CG1656, CG17575, and CG9997) appear to modulate the long-term response, which is the maintenance of post-mating behavior and physiological changes. The long-term post-mating response requires presence of sperm in storage and, until now, had been known to require only a single Acp. Here, we discovered several novel Acps together are required which together are required for sustained egg production, reduction in receptivity to remating of the mated female and for promotion of stored sperm release from the seminal receptacle. Our results also show that members of conserved protein classes found in seminal plasma from insects to mammals are essential for important reproductive processes.
The many hues of plant heterochromatin
Jeffrey L Bennetzen
Genome Biology , 2000, DOI: 10.1186/gb-2000-1-1-reviews107
Abstract: Despite comprising the majority of many eukaryotic chromosomes, heterochromatin remains the least characterized and least understood portion of the higher eukaryotic genome. Traditionally, heterochromatin (literally, different in 'color' or staining properties) has been defined by the cytogenetic criterion that it has a different appearance from the more open euchromatic regions of eukaryotic chromosomes that contain most of the expressed genes. Even the first staining of higher eukaryotic chromosomes, however, indicated many different degrees of heterochromatic condensation and different sizes of heterochromatic blocks. Moreover, some heterochromatin has traditionally been associated with centromere or neocentromere function, while other regions appear not to have such activities [1]. In Drosophila, some heterochromatic regions (β heterochromatin) contain active genes, whereas other regions of heterochromatin (α heterochromatin) apparently lack active genes. Most euchromatic genes in Drosophila show abolished or attenuated expression when translocated into or near heterochromatic regions. In contrast, β heterochromatin genes like light show a reversal of this position effect leading to decreased activity when they are moved into euchromatin [2]. Hence, heterochromatin is a term that describes many different types of relatively condensed chromatin, perhaps with many different features and roles.Recent advances in genomic sequencing technologies now make it possible (albeit challenging) to characterize fully the DNA composition of heterochromatic regions. In addition, more powerful cytogenetic tools now allow more fine-tuned studies of the nature and dynamic properties of heterochromatin in situ. Two articles in the February 4 issue of Cell [3,4] describe complementary DNA sequence and cytogenetic characterizations of a heterochromatic knob present on Arabidopsis chromosome 4.Paul Fransz and coworkers [3] provide a uniquely detailed and comprehensive cytogenetic anal
Prospective open-label study of add-on and monotherapy topiramate in civilians with chronic nonhallucinatory posttraumatic stress disorder
Jeffrey L Berlant
BMC Psychiatry , 2004, DOI: 10.1186/1471-244x-4-24
Abstract: Thirty-three consecutive newly recruited civilian adult outpatients (mean age 46 years, 85% female) with DSM-IV-diagnosed chronic PTSD, excluding those with concurrent auditory or visual hallucinations, received topiramate either as monotherapy (n = 5) or augmentation (n = 28). The primary measure was a change in the PTSD Checklist-Civilian Version (PCL-C) score from baseline to 4 weeks, with response defined as a ≥ 30% reduction of PTSD symptoms.For those taking the PCL-C at both baseline and week 4 (n = 30), total symptoms declined by 49% at week 4 (paired t-test, P < 0.001) with similar subscale reductions for reexperiencing, avoidance/numbing, and hyperarousal symptoms. The response rate at week 4 was 77%. Age, sex, bipolar comorbidity, age at onset of PTSD, duration of symptoms, severity of baseline PCL-C score, and monotherapy versus add-on medication administration did not predict reduction in PTSD symptoms. Median time to full response was 9 days and median dosage was 50 mg/day.Promising open-label findings in a new sample converge with findings of a previous study. The use of topiramate for treatment of chronic PTSD, at least in civilians, warrants controlled clinical trials.Posttraumatic stress disorder (PTSD) is a difficult-to-treat condition that over a lifetime affects approximately 10% of the general population [1]. The condition develops after traumatic events such as combat, terror activities, disaster, or rape, and has 3 main features: (1) reexperiencing the trauma through recollection, dreams, and reliving, (2) avoidance of thoughts, activities, and emotions associated with the trauma, and (3) hyperarousal [2]. PTSD is usually a chronic disorder, with one third of patients displaying symptoms for ≥ 10 years after experiencing the traumatic event [3,4]. Generally the response to pharmacotherapy has been poor, with many patients completely unresponsive and others only marginally responsive [5]. Some tricyclic antidepressants, monoamine oxidase inhibi
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