Cocaine- and amphetamine-regulated transcript in the rat vagus nerve: A putative mediator of cholecystokinin-induced satiety

Cocaine- and amphetamine-regulated transcript (CART) is widely expressed in the central nervous system. Recent studies have pointed to a role for CART-derived peptides in inhibiting feeding behavior. Although these actions have generally been attributed to hypothalamic CART, it remains to be determined whether additional CART pathways exist that link signals from the gastrointestinal tract to the central control of food intake. In the present study, we have investigated the presence of CART in the rat vagus nerve and nodose ganglion. In the viscerosensory nodose ganglion, half of the neuron profiles expressed CART and its predicted peptide, as determined by in situ hybridization and immunohistochemistry. CART expression was markedly attenuated after vagotomy, but no modulation was observed after food restriction or high-fat regimes. A large proportion of CART-labeled neuron profiles also expressed cholecystokinin A receptor mRNA. CART-peptide-like immunoreactivity was transported in the vagus nerve and found in a dense fiber plexus in the nucleus tractus solitarii. Studies on CART in the spinal somatosensory system revealed strong immunostaining of the dorsal horn but only a small number of stained cell bodies in dorsal root ganglia. The present results suggest that CART-derived peptides are present in vagal afferent neurons sensitive to cholecystokinin, suggesting that the role of these peptides in feeding may be explained partly by mediating postprandial satiety effects of cholecystokinin.

Ancient mtDNA sequences in the human nuclear genome: A potential source of errors in identifying pathogenic mutations

Nuclear-localized mtDNA pseudogenes might explain a recent report describing a heteroplasmic mtDNA molecule containing five linked missense mutations dispersed over the contiguous mtDNA CO1 and CO2 genes in Alzheimer’s disease (AD) patients. To test this hypothesis, we have used the PCR primers utilized in the original report to amplify CO1 and CO2 sequences from two independent ρ° (mtDNA-less) cell lines. CO1 and CO2 sequences amplified from both of the ρ° cells, demonstrating that these sequences are also present in the human nuclear DNA. The nuclear pseudogene CO1 and CO2 sequences were then tested for each of the five “AD” missense mutations by restriction endonuclease site variant assays. All five mutations were found in the nuclear CO1 and CO2 PCR products from ρ° cells, but none were found in the PCR products obtained from cells with normal mtDNA. Moreover, when the overlapping nuclear CO1 and CO2 PCR products were cloned and sequenced, all five missense mutations were found, as well as a linked synonymous mutation. Unlike the findings in the original report, an additional 32 base substitutions were found, including two in adjacent tRNAs and a two base pair deletion in the CO2 gene. Phylogenetic analysis of the nuclear CO1 and CO2 sequences revealed that they diverged from modern human mtDNAs early in hominid evolution about 770,000 years before present. These data would be consistent with the interpretation that the missense mutations proposed to cause AD may be the product of ancient mtDNA variants preserved as nuclear pseudogenes.

Three-dimensional image reconstruction of dephosphorylated smooth muscle heavy meromyosin reveals asymmetry in the interaction between myosin heads and placement of subfragment 2

Regulation of the actin-activated ATPase of smooth muscle myosin II is known to involve an interaction between the two heads that is controlled by phosphorylation of the regulatory light chain. However, the three-dimensional structure of this inactivated form has been unknown. We have used a lipid monolayer to obtain two-dimensional crystalline arrays of the unphosphorylated inactive form of smooth muscle heavy meromyosin suitable for structural studies by electron cryomicroscopy of unstained, frozen-hydrated specimens. The three-dimensional structure reveals an asymmetric interaction between the two myosin heads. The ATPase activity of one head is sterically “blocked” because part of its actin-binding interface is positioned onto the converter domain of the second head. ATPase activity of the second head, which can bind actin, appears to be inhibited through stabilization of converter domain movements needed to release phosphate and achieve strong actin binding. When the subfragment 2 domain of heavy meromyosin is oriented as it would be in an actomyosin filament lattice, the position of the heads is very different from that needed to bind actin, suggesting an additional contribution to ATPase inhibition in situ.

The loss of female sex pheromone after mating in the corn earworm moth Helicoverpa zea: identification of a male pheromonostatic peptide.

Female moths often become depleted of sex pheromone after mating as the various components of virgin behavior are switched off. In examining a potential male contribution to these events in the corn earworm moth Helicoverpa zea, we have characterized a basic polypeptide from the tissues producing (accessory glands) and storing (duplex) the seminal fluids. The peptide evokes the depletion of sex pheromone when injected into virgin females. This pheromonostatic peptide (PSP) is 57 amino acids long and contains a single disulfide bridge. It is blocked at the N terminus with pyroglutamate and at the C terminus by amidation. As little as 23 ng of peptide evokes the near-complete depletion of pheromone in decapitated (neck-ligated) females that had been injected with pheromone biosynthesis-activating neuropeptide. Activity is approximately 15-fold less in intact virgins, showing that the head limits the expression of activity in these injected females. Females mated to surgically impaired males, capable of producing a spermatophore but not transferring spermatozoa or seminal fluids, are depleted of pheromone by injected peptide. Females whose abdominal nerve cords have been severed are not depleted of pheromone after mating. Thus, neural signals either descending or ascending via the nerve cord are required for the depletion of pheromone after mating. PSP, from the seminal fluids, may participate in this process by direct or indirect action on the glandular tissue; if so, it represents an unusual mechanism in insects for the regulation by seminal fluids of postmating reproductive behavior.

Identification of mutations in the Wiskott-Aldrich syndrome gene and characterization of a polymorphic dinucleotide repeat at DXS6940, adjacent to the disease gene.

The Wiskott-Aldrich syndrome (WAS) is an X-chromosome-linked recessive disease characterized by eczema, thrombocytopenia, and immunodeficiency. The disease gene has been localized to the proximal short arm of the X chromosome and recently isolated through positional cloning. The function of the encoded protein remains undetermined. In this study we have characterized mutations in 12 unrelated patients to confirm the identity of the disease gene. We have also revised the coding sequence and genomic structure for the WAS gene. To analyze further the transmittance of the disease gene, we have characterized a polymorphic microsatellite at the DXS6940 locus within 30 kb of the gene and demonstrate the inheritance of the affected alleles in families with a history of WAS.

Mental health literacy of Latina women in the United States for their school-aged children

Despite known mental health (MH) disparities faced by Latino children relative to children from other minority groups of similar socioeconomic status (SES), little is known about how Latina mothers make MH decisions for their children. The present study examined links between Latina mothers' mental health literacy (MHL), including the recognition of and response to child psychiatric symptoms, and maternal acculturation factors as well as interpersonal violence (IPV) related symptomatology. Participants were 80 Latina mothers from Denver, Colorado and Modesto, California with at least one child between the ages of 8-12 years. Mothers were presented vignettes depicting child internalizing and externalizing disorders as well as interviewed about their help seeking behaviors. Maternal acculturation was not related to identification of disorders, but was related to more symptoms recognized for child internalizing and externalizing symptoms. Acculturation predicted use of formal source of care for child internalizing and externalizing disorder. Women demonstrated a preference for informal source of care, with the exception of IPV-related child symptoms, where women demonstrated a preference for formal source of care. IPV-related symptoms did not moderate the relationship between acculturation and MHL. The relationship between maternal acculturation, IPV related symptomatology and their combined effect on MHL for child psychiatric disorders are discussed.

Paleoecology, Diagenesis and Biological Affinity of Tetradiids in the Upper Ordovician (Sandbian) Black River Group of the Kingston Area, Ontario, Canada

Tetradiids are a group of colonial, tubular fossils that occur globally in Middle to Upper Ordovician strata. Tetradiids were first described as a type of tabulate coral; however, based on their four-fold symmetry, division, and presence of a central-sparry canal, they were recently reinterpreted as a florideophyte rhodophyte algae, a reinterpretation that is tested in this thesis. This study focused on understanding the affinity and taphonomy of this order of fossil. Research was conducted by stratigraphic and petrographic analyses of the Black River Group in the Kingston, Ontario region. Tetradiid occurrences were divided into fragment or colonial, with three morphologies of tetradiids described (Tetradium, Phytopsis and Paratetradium). Morphology is specific to depositional environment, with compact Tetradium consistently within ooid grainstones and open branching Phytopsis and chained Paratetradium consistently within mudstones. Two types of patch reefs were recognized: a Paratetradium bioherm, and a Paratetradium, Phytopsis, stromatolite bioherm. The presence of bioherms implies that tetradiids were capable of hypercalcifying. Preservation styles of tetradiids were investigated, and were compared to brachiopods, echinoderms, mollusks, and ooids. Tetradiids were preferentially preserved as molds and demonstrated complete dissolution of skeletal material. Rare specimens, however, demonstrated preserved horizontal partitions, central plates, and a double wall. Skeletal molds were filled with either calcite spar, mud or encrusted by a cryptomicrobial colony. Both calcitic and aragonitic ooids were discovered. The co-occurrence of aragonitic ooids, aragonitic crytodontids, and the evolution of aragonitic, hypercalcifying tetradiids is interpreted as representing the geochemical favoring of aragonite and HMC in a time of global calcite seas. The geochemical favoring of aragonite is interpreted to be independent to global Mg: Ca ratios, but was the result of increased saturation levels and temperature driven by high atmospheric pCO2. Based on the presence of epitheca, tabulae, septa, and the commonality of growth forms, tetradiids are interpreted as an order of Cnidaria. The evolution of an aragonitic skeleton in tetradiids is interpreted to be the result of de novo acquisition of a skeleton from an unmineralized clade.