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R D Gates

Publications and source records attributed to R D Gates.

9 recordsLinked to original sources
PubMed2001

The isolation of a Distal-less gene fragment from two molluscs.

The transcription factor, Distal-less, and its orthologues (e.g. DLL/Dlx) are best known for their roles in proximo-distal and nervous system patterning as well as for their use in inferring the evolution of limbs and other proximo-distal structures. However, evolutionary applications to non-model taxa have primarily employed a polyclonal antibody, and sequence data are generally lacking. We have designed a degenerate PCR primer set specific to the recovery of a Distal-less gene fragment, and present sequence data for two bivalve molluscs, Crassostrea gigas and Nutricola sp. These sequences represent the first Distal-less homologs isolated from lophotrochozoan taxa.

Amino Acid Sequence↗
PubMed1995

Free amino acids exhibit anthozoan "host factor" activity: they induce the release of photosynthate from symbiotic dinoflagellates in vitro.

Reef-building corals and other tropical anthozoans harbor endosymbiotic dinoflagellates. It is now recognized that the dinoflagellates are fundamental to the biology of their hosts, and their carbon and nitrogen metabolisms are linked in important ways. Unlike free living species, growth of symbiotic dinoflagellates is unbalanced and a substantial fraction of the carbon fixed daily by symbiont photosynthesis is released and used by the host for respiration and growth. Release of fixed carbon as low molecular weight compounds by freshly isolated symbiotic dinoflagellates is evoked by a factor (i.e., a chemical agent) present in a homogenate of host tissue. We have identified this "host factor" in the Hawaiian coral Pocillopora damicornis as a set of free amino acids. Synthetic amino acid mixtures, based on the measured free amino acid pools of P. damicornis tissues, not only elicit the selective release of 14C-labeled photosynthetic products from isolated symbiotic dinoflagellates but also enhance total 14CO2 fixation.

Journal Article↗
PubMed1991

Rapid staining for the sperm penetration assay using a bisbenzimide dye.

Our rapid staining method, accomplished by adding the vital fluorochrome bisbenzimide (Hoechst 33342) directly into the sperm droplet before fertilization, eases visual interpretation of sperm penetration and decondensation. For both within- and between-experiment comparisons, inclusion of bisbenzimide did not influence the overall SPA score or the progress of sperm-egg interaction. These results suggest that bisbenzimide can be used routinely to facilitate scoring of the SPA.

Animals↗
PubMed1987

Single-case study of left cerebral hemispherectomy: development in the first five years of life.

A prospective single-case study of an infant who underwent surgical removal of the entire left cerebral hemisphere at 6 months of age is presented to address, in part, the issue of cerebral hemispheric specialization of function. Serial developmental assessments were made using standardized clinical instruments. A preoperative assessment revealed normal development while postoperative assessments generally revealed delayed development but with a normal rate of maturation. These results are discussed in relation to the issues of early functional specialization of the cerebral cortex and functional plasticity following early brain trauma. In particular, the evidence is interpreted as suggesting that the effect of left hemispherectomy early in life was effectively to delay normal development, and that no specific impairment of either linguistic-communicative or visual-motor/visual-spatial development was apparent.

Angiomatosis↗
PubMed1987

Neuropsychological studies on adolescents with phenylketonuria returned to phenylalanine-restricted diets.

Nine adolescents with phenylketonuria (PKU), who had been on unrestricted diets for 2 to 11 years, underwent serial neuropsychological testing over two consecutive 4- to 5-week periods during which each was maintained on a low-phe diet supplemented in a triple-blind fashion either with L-phe (high phe) or L-alanine (low phe). Assignment to the initial condition was done randomly, and the alternate condition was substituted at the end of the first 4- to 5-week period. In 6 of 7 subjects with PKU, baseline median choice reaction times (RTs) were slower than those of controls matched for age, sex, handedness, and Full-Scale IQ (WISC-R). A highly significant improvement occurred during the low-phe phases of the study. Results suggest that adolescents with PKU on unrestricted diets have a neuropsychological deficit that is out of proportion to their overall intellectual handicap. Moreover, this deficit appears to be at least partly reversible by return to dietary phe restriction despite years of hyperphenylalaninemia.

Adolescent↗
PubMed1986

Interpretation of the Personality Inventory for Children-Revised (PIC-R): influence of cognitive impairment.

The Personality Inventory for Children-Revised (PIC-R) is a parent-report measure of social-emotional adjustment for children 3 to 16 years of age. The present study examined the clinical value of the PIC-R by exploring the impact of age and developmental status on PIC-R profiles, particularly on the Psychosis (PSY) scale, within a sample of preschool and school-age children referred for assessment of suspected cognitive impairment and learning problems. Compared to school-age children, significantly more preschoolers obtained elevated scores on the Psychosis scale; those preschoolers with cognitive impairments were even more likely to obtain significantly elevated Psychosis scale scores, despite the absence of diagnosed childhood psychosis. No significant relationship was found between Psychosis scale elevations and cognitive impairment in the school-age group. The PIC-R was moderately accurate in identifying cognitively impaired preschoolers but only minimally accurate in identifying cognitively impaired school-age children.

Adolescent↗
PubMed1986

Experience with adolescents with phenylketonuria returned to phenylalanine-restricted diets.

In order to test the feasibility of returning older children with classical phenylketonuria (PKU) to therapeutically and nutritionally adequate phenylalanine-restricted diets after 8 to 13 years of unrestricted diets, 7 adolescents (13 to 19 years old) of normal or near-normal intelligence with classical PKU were returned to phenylalanine-limited diets for periods of 8 to 10 weeks. During a 4- to 5-week period when the phenylalanine-restricted diet was supplemented with added L-phenylalanine to mimic pretreatment conditions, plasma phenylalanine levels were 1,327 +/- 282 microM on total phenylalanine intakes of 2,794 +/- 248 mg/day (55.3 +/- 11.5 mg/kg/day). During a similar period of dietary phenylalanine restriction, plasma phenylalanine levels were successfully maintained at 713 +/- 266 microM on dietary intakes of 655 +/- 210 mg/day (12.6 +/- 4.3 mg/kg/day). On the basis of 3-day diet records, the intakes of total protein, energy, calcium, phosphorus, iron, vitamins D, E, and A, ascorbic acid, thiamin, riboflavin, niacin, folacin, and vitamin B-12 over the entire 8- to 10-week study period were adequate by the standards of the Recommended Nutrient Intakes (RNI) for Canada, where the study was undertaken. Intakes of magnesium and zinc were significantly lower than the RNI. Although the return to nutritionally and therapeutically adequate dietary phenylalanine restriction was judged to be successful in each case, the amount and intensity of re-education and reinforcement required to maintain compliance was much greater than anticipated.

Adolescent↗
PubMedDate not supplied

Molluscan engrailed expression, serial organization, and shell evolution.

Whether the serial features found in some molluscs are ancestral or derived is considered controversial. Here, in situ hybridization and antibody studies show iterated engrailed-gene expression in transverse rows of ectodermal cells bounding plate field development and spicule formation in the chiton, Lepidochitona cavema, as well as in cells surrounding the valves and in the early development of the shell hinge in the clam, Transennella tantilla. Ectodermal expression of engrailed is associated with skeletogenesis across a range of bilaterian phyla, suggesting a single evolutionary origin of invertebrate skeletons. The shared ancestry of bilaterian-invertebrate skeletons may help explain the sudden appearance of shelly fossils in the Cambrian. Our interpretation departs from the consideration of canonical metameres or segments as units of evolutionary analysis. In this interpretation, the shared ancestry of engrailed-gene function in the terminal/posterior addition of serially repeated elements during development explains the iterative expression of engrailed genes in a range of metazoan body plans.

Animals↗