Biomedical subjects

D Morse

Publications and source records attributed to D Morse.

At least 37 records · Page 2Linked to original sources

PubMed1997

Structure and organization of the peridinin-chlorophyll a-binding protein gene in Gonyaulax polyedra.

We have identified a major 32-kDa protein in the dinoflagellate Gonyaulax polyedra as a peridinin-chlorophyll a-binding protein (PCP), based on micro-sequence data and immunological cross-reaction with antibodies raised against PCP from another dinoflagellate species. A cDNA for this protein, identified by a PCR-based cloning strategy, encoded all 68 of the amino acids microsequenced, thus confirming the identity of the clone. The PCP gene is highly expressed at both the mRNA and protein levels, and only PCP transcripts corresponding in size to the cDNA sequence were detected. Slot blot analyses show that there are roughly 5000 copies of the PCP gene in Gonyaulax, making this gene one of the most highly repeated protein-coding genes ever reported, yet the sequence of the different gene copies in the genome appears extraordinarily well conserved as judged by Southern blot analyses. The gene, as indicated by Southern blot and PCR data, is suggested to be present in 5000 intronless copies arranged head to tail in the genome, separated by conserved 1-kb spacers. Based on the conserved sequence of the spacer region, its presence next to each of the PCP coding sequences, and the uniform size of the PCP transcript, we propose that this region represents a dinoflagellate transcriptional promoter. This putative promoter region contains none of the sequence elements for DNA-binding proteins involved in transcriptional initiation reported in other organisms.

Amino Acid Sequence↗

PubMed1997

Expression of a wheat ADP-glucose pyrophosphorylase gene during development of normal and water-stress-affected anthers.

In wheat (Triticum aestivum L.), water deficit during meiosis in the microspore mother cells (MMCs) induces pollen abortion, resulting in the failure of fertilization and a reduction in grain set. In stressed plants, meiosis in MMCs proceeds normally but subsequent pollen development is arrested. Unlike normal pollen grains, which accumulate starch during the late maturation phase, stress-affected anthers contain pollen grains with little or no starch. Stress also alters the normal distribution of starch in the anther wall and connective tissue. To determine how starch biosynthesis is regulated within the developing anthers of stressed plants, we studied the expression of ADP-glucose pyrophosphorylase (AGP), which catalyzes the rate limiting step of starch biosynthesis. Two partial-length cDNAs corresponding to the large subunit of AGP were amplified by RT-PCR from anther RNA, and used as probes to monitor AGP expression in developing anthers of normal and water-stressed plants. These clones, WAL1 and WAL2, had identical deduced amino acid sequences and shared 96% sequence identity at the nucleic acid level. In normal anthers, AGP expression was biphasic, indicating that AGP expression is required for starch biosynthesis both during meiosis and later during pollen maturation. AGP expression in stressed anthers was not affected during the first phase of starch accumulation, but was strongly inhibited during the second phase. We conclude from these results that the reduced starch deposition later in the development of stressed pollen could be the result of a lower expression of AGP. However, this inhibition of AGP expression is unlikely to be the primary cause of male sterility because anatomical symptoms of pollen abortion are observed prior to the time when AGP expression is inhibited.

Amino Acid Sequence↗

PubMed1996

Binding of a 3,3', 4,4'-tetrachlorobiphenyl (CB-77) metabolite to fetal transthyretin and effects on fetal thyroid hormone levels in mice.

The present study was conducted in order to study the effect of the PCB congener 3,3', 4,4'-tetrachlorobiphenyl (CB-77) on fetal thyroxin homeostasis in the mouse, and to examine a possible underlying mechanism behind the effect. C57BL mice were treated with 14C-labelled or unlabelled CB-77 (1 or 10 mg/kg body wt.) on day 13 of gestation, and control animals were treated with corn oil. The experiment was terminated at 4 days after exposure. Maternal and fetal plasma and livers, and whole fetuses for homogenate preparation, were collected and analysed for total radioactivity, in vitro binding of 125I-thyroxin to plasma transthyretin (TTR; a thyroxin-transporting protein), and free and total thyroxin (FT4, TT4) levels. Maternal plasma, fetal plasma and homogenates were also analyzed for presence of CB-77 and metabolites. Results showed a dose-dependent uptake of radioactivity in plasma and liver, fetal plasma 14C-levels being about five-times higher in 10 mg/kg dosed animals as after 1 mg/kg. Fetal; plasma levels of total radioactivity were four- to nine-times above maternal levels and corresponded to only one compound, the metabolite 4-OH-3,3', 4',5-tetrachlorobiphenyl (4-OH-tCB). 4-OH-tCB was the major metabolite also in whole fetuses, with only small amounts of the parent compound (approximately 15% of the 4-OH-tCB) and traces (approximately 6%) of two other metabolites, 2-OH-3,3, 4,4'-tetrachlorobiphenyl and 5-OH-3,3', 4,4'-tetrachlorobiphenyl. Polyacrylamide gel electrophoresis confirmed that the 14C-radioactivity in fetal plasma was bound to TTR, and revealed that in vitro binding of 125I-T4 to fetal TTR was reduced to 50% of control values in treated animals (10 mg/kg body wt.). Fetal plasma FT4 and TT4 levels were significantly decreased (64 and 55% of control fetuses) after 10 mg/kg treatment. In conclusion, exposure of pregnant mice to CB-77 results in the accumulation of the metabolite 4-OH-tCB in fetal mouse plasma. The metabolite binds to TTR and is accompanied by a significant decrease in fetal plasma T4 levels. A causative correlation between TTR binding and effects on T4 levels is suggested.

Animals↗

PubMed1996

Imaging the internal and external pore structure of membranes in fluid: TappingMode scanning ion conductance microscopy.

We have constructed a combined TappingMode atomic force microscope and scanning ion conductance microscope. The design is based on a bent glass pipette that acts as both the force sensor and conductance probe. Measuring the pipette deflection allows more stable feedback than possible with previous versions of the scanning ion conductance microscope. Using this microscope, we have imaged synthetic membranes in both contact and tapping modes under fluid. Although contact mode operation is possible, we found that our microscope provided higher contrast and less apparent sample damage in the topographic and ionic conductance images in the tapping mode.

Ions↗

PubMed1996

Phased protein synthesis at several circadian times does not change protein levels in Gonyaulax.

The synthesis rates of 13 individual proteins in Gonyaulax polyedra, resolved by two-dimensional gel electrophoresis, were estimated from the amount of 35S methionine incorporated during in vivo pulse labeling at 2-h intervals over one circadian period. The synthesis rates of three proteins, taken as controls, varied 2-3 fold, and no systematic pattern to these variations was apparent. In contrast, the synthesis rates of 10 other proteins varied at least tenfold and in a smooth and systematic pattern. The patterns of protein synthesis were placed into three different groups, the first occurring during the late day/early night phase, the second during the middle of the night phase, and the third during the late night/early day phase. The length of time that individual proteins within each group could incorporate radiolabel was variable, raising the possibility that additional groups might be present. However, both a replicate experiment in continuous light and a light:dark experiment confirmed the presence of at least three different groups of protein synthesis patterns. Unlike the circadian changes in the synthesis rate of the luciferin binding protein, which produces variations in protein levels that correlate with the bioluminescence rhythm, no substantial changes were found in the levels of any other rhythmically synthesized proteins examined.

Animals↗

PubMed1996

Impact of environmental regulations on cattle production.

A greater focus of legislative mandates is directed toward nonpoint sources of pollution. This article focuses on environmental regulations and their impact on cattle production. Key legislation will be reviewed to stress how variations in the type of law, degree of impact, enforcement mechanism, and time line for compliance affect the ability for research to be designed and accomplished in a desired time frame and to yield data on which imposed management practices should be based. Science-based regulations are desired to maximize beneficial impacts of management practices; however, many regulations are developed and management practices are imposed prior to research to minimize liability of the regulatory agency in case natural resources are degraded in the absence of management practices. The technology adoption process will be reviewed. Documented impact of imposed management practices (technology adoption) will be presented. Of particular interest is the importance of documenting the economic and resource impacts of regulations on livestock operators. Types of research needed prior to implementing management practices will be reviewed. Local involvement can increase the adoption rate of practices and technologies.

Animal Husbandry↗

PubMed1996

Impacts of water and air quality legislation on the poultry industry.

Poultry operators are faced with continually changing water and air quality regulations that may influence management decisions and economic viability. Informed extension, research and allied industry members may be able to respond to industry needs to develop research and disseminate findings. Implications of Reauthorization of the Coastal Zone Management Act and its potential impact on the next version of the Clean Water Act are presented. Also presented are air quality concerns related to ozone and particulate matter formation.

Air Pollution↗

PubMed1996

Several clocks may simplify the circadian system of Gonyaulax.

The circadian system of Gonyaulax involves at least two pacemaking oscillators. These oscillators have been shown to be distinct at the physiological level by an examination of their rhythmic periods under different conditions, their phase response to pulses of light and darkness and their ability to compensate the rhythms for changes in temperature. It is also known that Gonyaulax can restrict synthesis of different proteins to at least three different times of day. We suggest that the two known oscillators may each control synthesis of a differently timed class of proteins.

Animals↗

PubMed1996

Do dinoflagellates contain a Cdc2-like protein kinase?

A protein present in extracts of the dinoflagellate Gonyaulax that was capable of binding an antibody directed against the conserved Cdc2 kinase epitope EGVPSTAIREISLLKE was characterized by Western blot analysis and DNA sequencing and shown not to encode a Cdc2 kinase. The amount, size, and isoelectric point of the immunoreactive species were invariant over a 24-hour period (encompassing S and M phases), and the DNA sequence of a cDNA isolated by immunologic screening showed that no conserved kinase regions were present in the deduced amino acid sequence. A method based on polymerase chain reaction (PCR), using primers designed from conserved regions in the Cdc2 kinases, was also unsuccessful in isolating a cdc2 gene homologue, although other kinases were identified.

Amino Acid Sequence↗

PubMed1995

A nuclear-encoded form II RuBisCO in dinoflagellates.

The chloroplasts of most dinoflagellates are unusual in that they are surrounded by three membranes and contain the carotenoid peridinin. The ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) in dinoflagellate chloroplasts was found here to also be unusual. Unlike other eukaryotes, dinoflagellates containing peridinin use a form of RuBisCO (form II) previously found only in some species of proteobacteria. Furthermore, this RuBisCO is not encoded in the chloroplast DNA, as is the case in other organisms, but is encoded by the nuclear DNA. The unusual nature of this enzyme and location of its gene support the idea that dinoflagellate chloroplasts may have had a distinctive evolutionary origin.

Amino Acid Sequence↗

PubMed1995

Knowledge and attitudes of healthcare workers about influenza: why are they not getting vaccinated?

In a survey of employees at a chronic care psychiatric facility following an influenza outbreak, previous influenza vaccination (relative risk [RR], 69.7; 95% confidence interval [CI95], 25.2 to 192.4), age > or = 50 years (RR, 2.4; CI95, 1.3 to 4.5), and knowledge that vaccine does not cause influenza (RR, 2.3; CI95, 1.3 to 3.7) were the factors most predictive of current influenza vaccination. Medical personnel were less likely than nonmedical employees to be vaccinated (RR, 0.5; CI95, 0.3 to 0.9). Educational efforts to address misconceptions about vaccination plus more vigorous administrative measures to vaccinate employees should be considered.

Adolescent↗

PubMed1995

Environmental considerations of livestock producers.

Regulatory agencies and citizens have placed great emphasis on sustainability of natural resources. Individuals involved in animal husbandry should understand the basic components associated with air and water quality issues. An increase in regulations governing land, air, and water resources increases the need for educators, researchers, and producers to realize impacts of current and potential legislation. Regulations and enforcement should be based on sound scientific data. Research scientists should play an active role in designing and carrying out research. Sustainability of land and economics of production are better incentives to entice producers to change than are regulations. Educational opportunities exist to promote environmental stewardship and the importance of maintaining natural resources. This paper will review current air and water quality regulations and provide examples of current activities that focus on environmental stewardship. Individuals should understand the importance of cooperative work to ensure that realistic enforcement and future regulation development be economically feasible and environmentally sound.

Air Pollution↗

PubMed1994

In vitro metabolism of 3,3',4,4'-tetrachlorobiphenyl in relation to ethoxyresorufin-O-deethylase activity in liver microsomes of some wildlife species and rat.

A qualitative study was performed of the capacity of hepatic microsomes of several wildlife species to metabolize 3,3',4,4'-tetrachlorobiphenyl (TCB). Hepatic microsomes of species environmentally exposed to polychlorinated biphenyls (PCBs): harbour porpoise (Phocoena phocoena), harbour seal (Phoca vitulina), common tern (Sterna hirundo), and hepatic microsomes from species experimentally exposed to PCBs: eider duck (Somateria mollissima), rainbow trout (Salmo gairdneri), flounder (Platichthys flesus), and Wistar rat, were incubated with 14C-labelled TCB ([14C]TCB). The mammals and birds were able to metabolize TCB at a rate that correlated with their ethoxyresorufin-O-deethylase (EROD) activity. No [14C]TCB metabolism was observed in the fish, despite elevated EROD activity in the trout. HPLC analysis of diisopropylether extracts of the microsomal incubations indicated the presence of 4-OH-, 5-OH-, and 6-OH-tetrachlorobiphenyl metabolites and a yet unidentified metabolite. The ratio of the different hydroxy metabolites formed varied for the various species.

Animals↗

PubMed1994

The S11 and S13 self incompatibility alleles in Solanum chacoense Bitt. are remarkably similar.

A genomic clone of the S11 allele from the self-incompatibility locus (S locus) in Solanum chacoense Bitt. has been isolated by cross-hybridization to the S. chacoense S13 allele and sequenced. The sequence of the S11 allele contains all the features expected for S genes of the Solanaceae, and S11 expression, as assessed by northern blots and RNA-PCR, was similar to that of other S. chacoense S alleles. The S11 protein sequence shares 95% identity with the phenotypically distinct S13 protein of S. chacoense and is the gametophytic S allele with the highest similarity to an existing allele so far discovered. Only 10 amino acid changes differentiate the mature proteins from these two alleles, which sets a new lower limit to the number of changes that can produce an altered S allele specificity. The amino acid substitutions are not clustered, suggesting that an accumulation of random point mutations can generate S allele diversity. The S11 intron is unusual in that it could be translated in frame with the coding sequence, thus suggesting an additional mechanism for the generation of new S alleles.

Alleles↗

PubMed1994

Expression and genomic organization of a dinoflagellate gene family.

The luciferin-binding protein (LBP) of the dinoflagellate Gonyaulax polyedra is encoded by a large gene family with at least two different members. To more fully understand the expression and genomic organization of this gene family, 40 full-length LBP cDNAs were isolated and mapped with the restriction enzymes Xho I, Eco RI, Pvu II and Hind III. All cDNAs isolated could be placed into one of two groups called LBP alpha and LBP beta. Two LBP alpha group cDNAs were completely sequenced and were found to share 99% identity at both the nucleotide and protein levels. One LBP beta cDNA was sequenced and was found to share only 86% sequence identity with the LBP alpha group at both the nucleotide and protein levels. Both groups of message appear to be expressed at nearly equal levels since (1) two-dimensional gels of purified LBP show two protein isoforms present in roughly equal amounts and (2) northern blots using group-specific probes suggest that cellular levels of LBP alpha and LBP beta mRNAs are identical. Genomic Southern blots using group-specific probes suggests that the copy number of both gene groups is very similar and that LBP gene loci are organized as tandem repeats of either LBP alpha or LBP beta sequences.

Amino Acid Sequence↗

PubMed1994

Parvovirus B19 outbreak on an adult ward.

In November and December 1992, an outbreak of parvovirus B19 infection occurred among patients and staff on an adult mixed surgical ward at a large hospital in London. Three patients and 15 staff members were serologically confirmed as acute cases. The attack rate among susceptible members of staff was 47%. In those infected, arthralgia (80%) and rash (67%) were the most common symptoms. Of six susceptible in-patients on the ward, three became infected. One of the in-patients who had carcinoma of the mouth was viraemic for more than 10 days with marrow suppression resulting in the postponement of chemotherapy until intravenous immunoglobulin was given and he was no longer viraemic. Control measures taken included closure of the ward to new admissions, transfer of only immune staff to the ward, and restriction of the ward nursing staff to working only on that ward. Although no specific exposure was conclusively identified as a risk factor, there was a suggestion of an increased risk of acquiring parvovirus B19 infection among those staff who did not adopt strict hand washing procedures after each physical contact with a patient (RR = 2.33; P = 0.07). Knowledge of parvovirus B19 among interviewed health care workers was poor: only 42% reported knowing about parvovirus B19 and only 38% could name a patient category at risk of a severe outcome following infection. This is the first report of a nosocomial outbreak affecting an adult ward and of possible transmission of parvovirus B19 infection from staff to in-patients. Hospital control of infection teams should include parvovirus B19 in their outbreak containment plans.

Adult↗

PubMed1994

Outbreak of measles in a teenage school population: the need to immunize susceptible adolescents.

An outbreak of measles occurred in a community school and the surrounding area in Crowborough, East Sussex, UK, from December 1992 to February 1993. There were 96 suspected cases reported: 66 cases among 1673 students at one school and 30 community cases. The majority of suspected cases were in those aged 11-17 (78%), 2 cases occurred in infants < 1 year old and 8 cases in adults aged 18 years or over. Data collected on 60 (91%) of the 66 suspect school cases showed 56 (93%) had an illness which met a case definition of measles. Eighteen had confirmatory IgM measles antibody. Two cases were hospitalized. The local percentage uptake for measles immunization for the school age years affected varied between 64% and 84%. A survey of parents showed that approximately 74% of the students attending the school had a history of measles immunization. The immunization rates reported by parents for children who developed measles was 21%, (29% based on GP records) compared with 77% for those who remained well. Vaccine efficacy was estimated to be 92%. This outbreak, along with others recently reported in older unimmunized children in the UK, reinforces the need for catch-up immunization programmes to reach this susceptible group of adolescents.

Adolescent↗

PubMed1994

Different phase responses of the two circadian oscillators in Gonyaulax.

Two circadian oscillators have been previously shown to exist in the unicellular alga Gonyaulax polyedra by virtue of different periods for two different rhythms, which occur under certain experimental conditions. Here we show that phase shifts in response to light pulses also differ for these two rhythms. The phase response curves (PRCs) for white or blue light pulses are similar in shape and amplitude, but are somewhat displaced in time and have a slightly larger delay portion for the aggregation rhythm, corresponding to the A oscillator. In contrast, the aggregation rhythm PRC for dark pulses in a red light background has a much larger amplitude than that for the bioluminescence rhythm (B oscillator). These results suggest that the light input mechanism of the B oscillator is mainly blue-sensitive, whereas that of the A oscillator is sensitive to both red and blue light. This is supported by entrainment experiments: Dark pulses given as a skeleton 24-hr scotoperiod in a blue light background act as a strong zeitgeber for both oscillators. But if red light is used as background, there is bistability in the entrainment of the B oscillator, whereas the A oscillator is entrained to a definitive phase angle, regardless of the cells' prior phase of entrainment. Finally, the two oscillators can be differentially entrained with 22-hr T cycles using 3-hr dark pulses interrupting red light (19 hr), whereas both oscillators are entrained when the dark pulses interrupt blue light.

Circadian Rhythm↗