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Biomedical subjects

M O Harris

Publications and source records attributed to M O Harris.

11 recordsLinked to original sources
PubMed2006

Is resistance to Bacillus thuringiensis endotoxin Cry1Ac associated with a change in the behavior of light brown apple moth larvae (Lepidoptera: Tortricidae)?

Bacillus thuringiensis (Bt)-resistant light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), created by selection of a laboratory colony with artificial diets containing the Bt endotoxin Cry1Ac, were used to explore relationships between larval behavior and resistance to toxins. Our hypothesis was that behavioral responses during the first days of exposure to diet are directly related to the toxicity of the diet, as measured by subsequent mortality. We tested two predictions from this hypothesis. The first prediction was that susceptible larvae and resistant larvae exhibit similar behavior on diet without toxins, settling at feeding sites within a few hours. The second prediction was that susceptible and resistant larvae differ in their behavior on Cry1Ac diet to the same degree that their mortality differs, i.e., on Cry1Ac diet, resistant larvae exhibit anorexia and walking to a lesser degree than susceptible larvae. Predictions were tested by making observations over 2 wk, with each larva held individually in a 10-cm-long cylindrical glass arena with two aliquots of diet. The two aliquots consisted of either the same diet (two no-choice treatments: control/control or Cry 1Ac/Cry1Ac) or different diets (one choice treatment: control/Cry 1Ac). The two predictions did not accurately describe larval behavior. On control diet, behavior differed, with resistant larvae settling more quickly than susceptible larvae. On Cry1Ac diet, behavior was more similar than expected. Thus, even though the Bt diet was much less toxic to resistant larvae, resistant larvae seemed to match the ability of susceptible larvae to reduce exposure to Bt diet while increasing exposure to nontoxic control diet.

Animals↗
PubMed2006

Does R gene resistance allow wheat to prevent plant growth effects associated with Hessian fly (Diptera: Cecidomyiidae) attack?

Resistance genes (R genes) are an important part of the plant's immune system. Among insects, the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), larva is the target of the greatest number of characterized R genes (H1-H32). The biochemical/molecular mechanism of R gene resistance to Hessian fly is not well understood. In the absence of an effective R gene, larvae caused extensive growth deficits (> 30 cm) in wheat seedlings. In the presence of one of three effective R genes, H6, H9, or H13, larvae caused small growth deficits (approximately 3-4 cm) in two leaves (third and fourth) that were actively growing during the first days of larval attack. After larvae died on R gene plants, the fifth leaf and tiller leaves exhibited small increases in growth (2-4 cm). Growth responses of susceptible and resistant plants diverged at a time when Hessian fly larvae were establishing a nutritive gall tissue at feeding sites. The results of this study support the hypothesis that R gene resistance cannot prevent initial larval attack, but, by stopping the formation of the larval gall, it prevents the most serious consequences of larval attack.

Animals↗
PubMed2002

Grasses and gall midges: plant defense and insect adaptation.

The interactions of two economically important gall midge species, the rice gall midge and the Hessian fly, with their host plants, rice and wheat, respectively, are characterized by plant defense via R genes and insect adaptation via avr genes. The interaction of a third gall midge species, the orange wheat blossom midge, with wheat defense R genes has not yet exhibited insect adaptation. Because of the simple genetics underlying important aspects of these gall midge-grass interactions, a unique opportunity exists for integrating plant and insect molecular genetics with coevolutionary ecology. We present an overview of some genetic, physiological, behavioral, and ecological studies that will contribute to this integration and point to areas in need of study.

Adaptation, Physiological↗
PubMed2001

Pseudoaneurysm of the proximal facial artery presenting as oropharyngeal hemorrhage.

BACKGROUND: Penetrating trauma to the neck traversing zones II and III may cause considerable damage to soft tissues and neurovascular structures. Delayed sequelae of vascular injuries, such as pseudoaneurysm (PA), may present weeks to months after the initial injury. METHODS: We report an unusual case of a traumatic PA of the proximal facial artery that ruptured into the oropharynx. RESULTS: A 30-year-old man presented with oropharyngeal hemorrhage one month after a gunshot wound to the neck. Angiography revealed a PA of the proximal facial artery, which was treated with embolization. The arterial injury leading to the pseudoaneurysm had not been detected by arteriography at the time. CONCLUSIONS: PAs are rare complications of penetrating neck trauma. To our knowledge, this is only the second report of PA involving the proximal facial artery, and the first of a facial PA rupture into the pharynx.

Adult↗
PubMed2000

Human papillomavirus infection in "young" versus "old" patients with squamous cell carcinoma of the head and neck.

BACKGROUND: Human papillomavirus (HPV) represents a potential risk factor for squamous cell cancer of the head and neck (SCCHN). We evaluated the prevalence of HPV DNA in patients with SCCHN diagnosed at the University of Michigan from 1994-1996. METHODS: Patients were stratified by age at diagnosis as "young" (<50 years; median, 39) or "old" (>50 years; median, 66). Fourteen "young" and 14 "old" were matched for tumor site, and 4 additional "old" patients were included. Specimens were analyzed by polymerase chain reaction for HPV DNA using 2 sets of consensus primers. HPV sequences were confirmed by Southern blot hybridization and typed with type-specific probes. RESULTS: Overall, 15 of 32 (46.9%) samples contained HPV sequences. HPV 16 was detected in 9 of 15 (60%), HPV-18 in 1 of 15 (6.6%), and 5 of 15 (33.3%) remained untyped by multiple methods. When stratified, 7 of 14 (50%) "young" were HPV-positive compared with 8 of 18 (44.4%) "old" (p =.76). Survival in patients with HPV-positive SCCHN was significantly longer than that for HPV-negative patients. CONCLUSIONS: The incidence of HPV in "young" versus "old" is not significantly different, suggesting similar roles for both groups. Patients with HPV-positive tumors may have a survival advantage relative to patients with HPV-negative tumors.

Adult↗
PubMed1998

The HPV 6 E6/E7 transforming genes are expressed in inverted papilloma.

A role for human papilloma virus (HPV) infection in the pathogenesis of head and neck neoplasms has gained support in recent years. Expression of two early-region HPV genes, E6 and E7, is widely accepted as essential for viral-induced carcinomas of the genital tract. These oncoproteins interact with the products of the cellular tumor suppressor genes, p53 and retinoblastoma, and inactivate them. Examining E6/E7 transforming gene expression is an important step toward elucidating the pathogenesis of HPV in head and neck neoplasms. We introduce nasal inverted papilloma (IP) as a novel system for evaluating viral genomic expression and transforming gene regulation of tumorigenesis by virtue of its association to HPV infection and potential for malignant progression. We describe here a reverse transcriptase-polymerase chain reaction approach for the detection of HPV E6/E7-specific transcripts in RNA extracted from IR. A primer pair flanking previously mapped HPV 6 E6/E7 splice donor/acceptor sites was used to direct amplification of cDNA. Reverse transcriptase-polymerase chain reaction experiments generated products representing the 1.2 Kb E1E4 splice transcript and a smaller unclassified fragment in IP from two patients. These results provide evidence for HPV 6 E6/E7 expression in IP with the potential to encode transforming proteins.

DNA, Viral↗
PubMed1998

Expression of human papillomavirus 6 in inverted papilloma arising in a renal transplant recipient.

A 36-year-old renal transplant recipient taking cyclosporin A presented with bilateral nasal polypoid lesions involving the nasal septum and lateral nasal walls. Pathologic findings from surgical excision demonstrated inverted papilloma (IP) with focal atypia and mild dysplasia. DNA extracted from the tissue was tested with the polymerase chain reaction (PCR) using human papillomavirus (HPV) E6 and L1 consensus primers. This revealed amplification of the expected size fragment consistent with the presence of HPV DNA. Hybridization of PCR products with HPV type-specific oligonucleotide probes revealed a strong signal with only HPV 6. This result was confirmed by PCR amplification with HPV 6 type-specific primers. RNA extracted from the tissue was subjected to reverse transcription PCR (RT-PCR) with a primer pair specific for viral E6/E7 transcripts. The HPV early proteins, E6 and E7, are the transforming proteins implicated as critical for tumorigenesis. RT-PCR experiments generated products representing the E1/E4 spliced transcript originating from the E6/E6 promoter and a smaller unclassified fragment. These results provide evidence for HPV 6 E6/E7 expression in IP, lending credence to the concept that HPV may play a role in the origin of this neoplasm. Histologically normal nasal tissue from the same patient contained HPV DNA and similar transcripts to those described in the IP specimen.

Adult↗
PubMed1997

Behavioral manipulation methods for insect pest-management.

We discuss methods using stimuli to manipulate behavior of a pest for the purpose of protecting a valued resource. The methods are divided into two categories: those that manipulate behavior over a long distance, e.g. volatile chemicals, visual, and auditory stimuli, and those that manipulate behavior at a short distance (<1 cm), e.g. involatile chemicals. Particular emphasis is placed on methods that have been developed through studies of pest behavior and on combining stimuli to increase efficacy. Future prospects for behavioral manipulation methods in pest management are discussed.

Journal Article↗
PubMed1995

Tyrosine phosphorylations specific to mitosis in human and hamster cells.

Changes in protein tyrosine phosphorylation are known to be important for regulating cell cycle progression. With the aim of identifying new proteins involved in the regulation of mitosis, we used an antibody against phosphotyrosine to analyze proteins from synchronized human and hamster cells. At least seven proteins were found that displayed mitosis-specific tyrosine phosphorylation in HeLa cells (pp165, 205, 240, 250, 270, 290, and approximately 400) and one such protein in hamster BHK cells (pp155). In synchronized HeLa and BHK cells, all proteins except HeLa pp165, pp205, and pp250 were readily detectable only in mitosis. Tyrosine phosphorylation of pp165, pp205, and pp250 was apparent during arrest in S phase, suggesting that cell cycle perturbations can affect the phosphorylation state of some of these proteins. In a related finding in BHK cells, pp155 underwent tyrosine phosphorylation when cells were forced into premature mitosis by caffeine treatment. Only one protein (pp135 in HeLa cells) was found to be dephosphorylated on tyrosine during mitosis. The above findings may prove helpful for isolating new cell cycle proteins that are important for both the normal regulation of mitosis and the mitotic aberrations associated with cell cycle perturbations and chemical treatments.

Animals↗
PubMed1990

Premature mitosis induced in mammalian cells by the protein kinase inhibitors 2-aminopurine and 6-dimethylaminopurine.

The protein kinase inhibitors 2-aminopurine (2-AP) and 6-dimethylaminopurine (6-DMAP) were used to examine the effects of protein dephosphorylation on the control of mitosis in mammalian cells. Both 2-AP and 6-DMAP induced premature mitosis in hamster fibroblasts that were arrested in S phase. This response was characterized by changes in cell morphology, breakdown of the nuclear envelope, and premature chromosome condensation. Premature mitosis was followed by a return to interphase morphology and reformation of the nuclear envelope around decondensed and fragmented chromatin to form numerous micronuclei. The activity of both compounds was dependent upon new protein synthesis but not new RNA synthesis. 2-AP and 6-DMAP acted cooperatively with each other and with caffeine, suggesting a common mechanism of action. In exponentially growing cells, 2-AP and 6-DMAP did not induce premature mitosis but did increase the frequency of binucleated cells by blocking cytokinesis. These findings support a role for protein dephosphorylation in the control of mitosis and indicate that cell cycle perturbations can modify this regulation.

2-Aminopurine↗