Browsing by Subject "nematode"
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Item Endoparasites of the digestive systems of four species of pocket gophers (Genus: Geomys) in TexasLebrasseur, Kaitlynn Marie; Dowler, Robert C; Ammerman, Loren K; Negovetich, Nicholas J; Burt, M. Scott; Hama, MarkThe 9 species of pocket gophers in the state of Texas are ecologically interesting in that their ranges overlap very little, leading to genetic and chromosomal variation in both pocket gopher hosts and their parasites. We examined 4 species of pocket gopher (Geomys attwateri, G. bursarius, G. personatus, and G. texensis) in Texas for helminth parasites of the digestive system. Both nematodes and cestodes were collected. Only 1 species of nematode was collected, and it was collected from all 4 pocket gopher species representing four new host records for the nematode Protospirura ascaroidea. Cestodes recovered were from two genera: Monoecocestus and Hymenolepis. There was no significant difference in prevalence or intensity of nematodes in pocket gopher hosts. Prevalence of cestode parasites varied significantly between G. bursarius and G. texensis. Intensity of cestode parasites did not differ significantly between species.Item Functional Dissection of the Sensory Rays in Caenorhabditis elegans Male Mating Behavior(2012-02-14) Koo, Pamela KristineThe nematode Caenorhabditis elegans, with its sequenced genome, compact nervous system and stereotyped behaviors is an ideal model organism in which to study the integration of sensory input with motor output. Male mating behavior is among the most complex of these behaviors and males utilize a number of sensory organs in its execution. Among these are the rays, which are nine pairs of sensory organs that are arranged laterally along the male tail. Each ray is composed of two ultra-structurally distinct neuron types, an A type and a B type, surrounded by a glia-like structural cell. Though compositionally identical, each pair of rays maintains a unique, genetically-hardwired identity based on wiring, morphology, and neurotransmitter fate. Three techniques were used to investigate the role of the rays in male mating behavior. First, cauterization of the tips of the rays removed their sensory endings, leading to ray neuron death. Second, a heterologous light-activated cation channel was utilized to activate specific ray neuron types. Finally, ray neuron types were genetically targeted to undergo apoptosis by expression of heterologous caspases. The results show that the rays play important roles in multiple steps of male mating behavior, including contact response, scanning, and turning. The rays as a whole mediate posture change and backing during contact response. The ability to respond to hermaphrodite contact is shared among the rays, as is initiation of backward locomotion, though all rays are required for efficient, prolonged backward scanning. Both A and B neuron types appear capable of initiating contact response. Direct activation of B neurons through ChR2 causes a contact response-like ventral tail flexure, and elimination of both A and B neurons reduces contact response. A neurons additionally have a unique role in turning.Item Prevalence and Intensity of the Sinus Roundworm, Skrjabingylus chitwoodorum, in Rabies-negative Skunks of TexasHughes, Malorri Rene; Dowler, Robert C; Ammerman, Loren K; Negovetich, Nicholas J; Dailey, Jeffrey DThe sinus roundworm, Skrjabingylus chitwoodorum, occurs in North American skunks (Mephitidae). Estimates of its distribution and prevalence have been largely based on the inspection of skunk skulls showing damage from Skrjabingylus infections. I examined 595 striped skunks (Mephitis mephitis) and 5 hog-nosed skunks (Conepatus leuconotus) that tested negative for rabies by the Texas Department of State Health Services between November 2010 and April 2015 to determine species of Skrjabingylus, prevalence and intensity of infection, and distribution in Texas by county. Prevalence of S. chitwoodorum in striped skunks was 48.7%. Mean intensity was 19.4 with a range from 1-181 nematodes. There was a left side bias in the host sinuses. Neither intensity nor prevalence of infections varied among ecoregions of Texas. The high prevalence of Skrjabingylus in rabies-negative skunks supports the hypothesis that behavioral changes due to skrjabingylosis may be responsible for the submission of many skunks for rabies testing.