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E L Ferguson

Publications and source records attributed to E L Ferguson.

At least 37 records · Page 2Linked to original sources
PubMed1995

A stomatin-like protein necessary for mechanosensation in C. elegans.

The mec-2 gene is required for the function of a set of six touch receptor neurons in the nematode Caenorhabditis elegans; mec-2 mutants, which are touch-insensitive, have touch cells that appear morphologically normal. Gene interaction studies suggest that mec-2 positively regulates the activity of the putative mechanosensory transduction channel (and the present paper), comprised in part of proteins encoded by the two degenerin genes mec-4 and mec-10 The central region of the mec-2 protein (MEC-2) is very similar to stomatin, an integral membrane protein (band 7.2b) in human red blood cells that is thought to regulate cation conductance. MEC-2-LacZ fusions are distributed along the touch receptor axons. This axonal distribution, which is mediated by the mec-2-specific amino terminus, is disrupted by mutations in mec-12, an alpha-tubulin gene needed for touch cell function. Our results indicate that MEC-2 links the mechanosensory channel and the microtubule cytoskeleton of the touch receptor neurons. Such linkage provides the basis for a mechanism of mechanosensation whereby microtubule displacement leads to channel opening.

Amino Acid Sequence↗
PubMed1995

A conserved system for dorsal-ventral patterning in insects and vertebrates involving sog and chordin.

Dorsal-ventral patterning within the ectoderm of the Drosophila embryo requires seven zygotic genes, including short gastrulation (sog). Here we demonstrate that sog, which is expressed in the ventrolateral region of the embryo that gives rise to the nerve cord, is functionally homologous to the chordin gene of Xenopus, which is expressed in the dorsal blastopore lip of the embryo and in dorsal mesoderm, in particular the notochord. We show by injections of messenger RNA that both sog and chordin can promote ventral development in Drosophila, and that sog, like chordin, can promote dorsal development in Xenopus. In Drosophila, sog antagonizes the dorsalizing effects of decapentaplegic (dpp), a member of the transforming growth factor-beta family. One of the dpp homologues in vertebrates, bmp-4, is expressed ventrally in Xenopus and promotes ventral development. We show that dpp can promote ventral fates in Xenopus, and that injection of sog mRNA counteracts the ventralizing effects of dpp. These results suggest the molecular conservation of dorsoventral patterning mechanisms during evolution.

Amino Acid Sequence↗
PubMed1995

An interactive 24-h recall technique for assessing the adequacy of trace mineral intakes of rural Malawian women; its advantages and limitations.

OBJECTIVES: To assess the relative validity of an interactive 24-h recall for estimating mineral intakes of rural Malawian women. DESIGN: Repeated interactive 24-h recalls were compared with weighed records collected for the same 2 days of food intake, and for 2 days 1-2 weeks prior and subsequent to the weighed record data collection period. SETTING: Three villages in traditional authority Jalasi, Mangochi District, Malawi. SUBJECTS: 60 rural pregnant women. RESULTS: Median daily intakes of most minerals (Ca, Fe, Zn, Mn) were comparable for the two methods, but slightly overestimated for recalled (R) intakes expressed per MJ (mg/MJ) compared to weighed (W) (R vs W = Ca, 48 vs 38; Fe, 2.1 vs 1.9; Zn, 0.9 vs 0.8; Mn, 0.40 vs 0.38; P < or = 0.05). By contrast, recalled median daily intakes of energy (kJ), protein (g) fat (g) and Cu (mg) were slightly underestimated (R vs W = 6588 vs 7824; 51 vs 57; 14 vs 15; 1.3 vs 1.6, respectively; P < or = 0.05). Discrepancies were attributed primarily to inaccurate estimates of main meal food portions [R vs W = nsima (the main meal cereal style) 475 vs 557; and legume relish 171 vs 118 P < or = 0.001]. For classifying intakes into tertiles, agreement between the two methods was poor for daily intakes (Cohen's kappa < 0.40), but fair when expressed per MJ, and as a percentage of energy from food groups (Cohen's kappa > or = 0.40). Variance ratios for recall data were higher than corresponding ratios for the weighed intakes (R vs W = for energy, 4.87 vs 0.87), indicating poorer recall measurement precision. CONCLUSION: Results emphasise the importance of selecting the dietary method according to the study objectives, and the nutrients required.

Adult↗
PubMed1994

Properties of cognitive maps constructed from texts.

Subjects in three experiments read texts describing the locations of landmarks in a fictitious town. Later they drew sketch maps and verified sentences describing the relative locations of the landmarks. We predicted that subjects would develop mental models of the town that were organized around important landmarks ("anchors"), as are cognitive maps constructed through real-world navigation. More specifically, we expected that landmarks used in the text as reference points for describing the locations of some other landmarks would emerge as anchors in the subjects' cognitive maps and would consequently be recalled more accurately. Results showed that subjects represented such reference-point landmarks more accurately than they did the locations of other landmarks. This effect was independent of: (1) the perspective from which the text was written (route or survey); (2) whether or not a map was present at learning; (3) the order of information in the text (linear or anchors-first), and (4) the amount of information available to the subjects while drawing sketch maps (the full text, the landmark names only, or no information).

Adult↗
PubMed1994

The relative validity of the repeated 24 h recall for estimating energy and selected nutrient intakes of rural Ghanaian children.

OBJECTIVES: To investigate the relative validity of the 24 h recall for rural southern Ghanaian children. DESIGN: Cross-sectional study, in which food consumption was estimated for the same two days, using the recall and weighed record dietary techniques. SETTING: Two villages in the Greater Accra Region of Ghana. SUBJECTS: 72 rural children (39 females and 33 males; 56.2 +/- 9.4 months). RESULTS: Overall agreement in the number of foods reported was noted for 42% of records; 53% of recalls under-reported and 5% over-reported the number of foods consumed. Over 65% of snacks compared to less than 6% of main meal foods were missed on recalls. Average recalled portions were similar to weighed with the exception of cereal staples; for Slepor 250 g vs 295 g, P = 0.007 and for Gidantuba 272 g vs 260 g, P = 0.02. Average daily recalled intakes of energy and most nutrients were lower (P < or = 0.05) than weighted intakes in Slepor, but similar in Gidantuba. In both villages, the recalled and weighted nutrient intakes per MJ, and percentage energy from food groups, were similar. Intraclass correlations between recalled and weighed intakes ranged from 0.06 (energy) to 0.78 (vitamin A) per day, and per MJ from 0.36 to 0.76 for Fe in Gidantuba and Slepor, respectively. Less than 35% of recalled energy and nutrient intakes were within +/- 10% of weighed intakes. CONCLUSIONS: The recall could be substituted for the weighted record to estimate average intakes of energy and most nutrients, dietary quality and food consumption patterns, provided the average recalled serving of cereal staples was accurately estimated. For assessment of individual intakes or snack consumption, however, the recall technique was invalid. SPONSORSHIP: The International Development Research Centre and Natural Sciences and Engineering Research Council of Canada.

Child↗
PubMed1993

The zinc nutriture of preschool children living in two African countries.

The zinc nutrition of rural Malawian children (24 females, 33 males; age 62 +/- 10 mo) consuming cereal-based diets was compared with that of rural Ghanaian children (43 females, 33 males; age 59 +/- 10 mo) consuming cereals or starchy staples, using hair zinc concentrations, growth and body composition indices, and dietary intakes. Intakes of energy, protein, Ca, Zn, dietary fiber and phytate at two seasons of the year were estimated from 3-d weighed food records, using analyzed and literature food composition values. The mean annual intakes of energy (5419 +/- 1081 vs. 4698 +/- 885 kJ), protein (31.8 +/- 7.0 vs. 24.1 +/- 6.8 g), Zn (7.4 +/- 1.9 vs. 5.1 +/- 1.1 mg) and phytate (1899 +/- 590 vs. 604 +/- 151 mg), and the mean molar ratios of [phytate]/[Zn] and [Ca] x [phytate]/[Zn] mmol per MJ (25 +/- 4 vs. 12 +/- 2 and 44 +/- 13 vs 20 +/- 8 mmol/MJ), were higher for Malawian than for Ghanaian children. More Malawian than Ghanaian children had [phytate]/[Zn] > or = 15 (72% vs. 0%) and were severely stunted (57 vs. 28%). Ninety-four percent of children in Malawi and 83% in the Ghanaian village of Slepor had low hair Zn concentrations (< 1.68 mumol/g) compared with 39% in Gidantuba, Ghana. In Gidantuba, children with low hair Zn concentrations had low upper-arm-muscle-area-for-age and upper-arm-muscle-area-for-height Z-scores. The high intakes of phytic acid relative to zinc in Malawi suggest that these children were at greater risk for inadequate zinc nutriture than their Ghanaian counterparts.

Analysis of Variance↗
PubMed1993

Cognitive style and perception: the relationship between category width and speech perception, categorization, and discrimination.

Category width, as defined by Pettigrew's (1958) Category Width Scale, is a cognitive variable that purportedly reveals individual differences in categorization strategy. Subjects differ in terms of broadness and narrowness of judgments of category width--to what extent they will accept exemplars as good instances of a category. We tested the hypothesis that category width would be related to how subjects behave in different speech perception tasks. Differences found between extremely broad and narrow categorizers on such tasks would be helpful in understanding the nature of the perceptual and cognitive processes underlying the category width distinction. No effects attributable to category width were found when results were analyzed in terms of subjects' (a) discrimination and feature evaluation of auditory and visual information in speech events, (b) integration of these sources of information, (c) the process of decision, and (d) subjective preference for a two-choice versus a nine-choice response method. The results from both male and female and broad and narrow categorizers supported the predictions made by a fuzzy logical model of perception (FLMP). In the FLMP, people have access to continuous information about each feature of a stimulus, they make independent evaluations of each feature based on this information, the various features are integrated, and a decision is made based on the relative support for the viable alternatives. Given the common processes involved in speech and other pattern perceptual-recognition tasks, we conclude that fundamental processes involved in pattern recognition are unlikely to vary with personality measures, such as category width.

Acoustic Stimulation↗
PubMed1992

Decapentaplegic acts as a morphogen to organize dorsal-ventral pattern in the Drosophila embryo.

Zygotic expression of the Drosophila TGF beta family member decapentaplegic (dpp) is required for the development of the dorsal embryonic structures. By injecting dpp transcripts into young embryos, we find that 2- to 4-fold increases in the concentration of injected RNA elicit progressively more dorsal cell fates: only low levels of dpp permit development of ventral ectoderm, intermediate dpp levels drive dorsal epidermal development, and high dpp levels drive cells to differentiate as the most dorsal pattern element, the amnioserosa. Localized dpp RNA injections into embryos that lack all known maternal and zygotic dorsal-ventral polarity indicate that dpp can both define embryonic polarity and organize detailed patterning within the ectoderm. We infer that dpp acts as an extracellular morphogen and that the graded activity of dpp specifies the pattern of ectodermal cell fates in the Drosophila embryo.

Animals↗
PubMed1992

Localized enhancement and repression of the activity of the TGF-beta family member, decapentaplegic, is necessary for dorsal-ventral pattern formation in the Drosophila embryo.

Seven zygotically active genes are required for normal patterning of the dorsal 40% of the Drosophila embryo. Among these genes, decapentaplegic (dpp) has the strongest mutant phenotype: in the absence of dpp, all cells in the dorsal and dorsolateral regions of the embryo adopt fates characteristic of more ventrally derived cells (Irish and Gelbart (1987) Genes Dev. 1, 868-879). Here we describe the phenotypes caused by alleles of another of this set of genes, tolloid, and show that tolloid is required for dorsal, but not dorsolateral, pattern. Extragenic suppressors of tolloid mutations were isolated that proved to be mutations that elevate dpp activity. We studied the relationship between tolloid and dpp by analyzing the phenotypes of tolloid embryos with elevated numbers of the dpp gene and found that doubling the dpp+ gene dosage completely suppressed weak tolloid mutants and partially suppressed the phenotypes of tolloid null mutants. We conclude that the function of tolloid is to increase dpp activity. We also examined the effect of doubling dpp+ gene dosage on the phenotypes caused by other mutations affecting dorsal development. Like tolloid, the phenotypes of mutant embryos lacking shrew gene function were suppressed by elevated dpp, indicating that shrew also acts upstream of dpp to increase dpp activity. In contrast, increasing the number of copies of the dpp gene enhanced the short gastrulation (sog) mutant phenotype, causing ventrolateral cells to adopt dorsal fates. This indicates that sog gene product normally blocks dpp activity ventrally. We propose that the tolloid, shrew and sog genes are required to generate a gradient of dpp activity, which directly specifies the pattern of the dorsal 40% of the embryo.

Animals↗
PubMed1992

Selenium intakes of children from Malawi and Papua New Guinea consuming plant-based diets.

Dietary selenium intakes were determined over three seasons for 66 children aged 4-6 y in rural Malawi, and at one season for 67 children aged 6-10 y in rural Papua New Guinea. The selenium content of the foods consumed was assessed using instrumental neutron activation analysis. Median intakes of selenium for the Malawian children were 20 micrograms per day, 21 micrograms per day, and 15 micrograms per day at harvest, postharvest, and preharvest seasons, respectively. More than 43% of the Malawian intakes were below the U.S. Recommended Dietary Allowances for 4-6 y olds (20 micrograms per day). Median intake of Se for the Papua New Guinean children was 20 micrograms per day, with 87% of the intakes below the recommended level for 7-10 y olds (30 micrograms per day). Statistical comparisons of selenium intakes over three seasons for the 51 children present in all survey periods revealed that mean intakes were not significantly different in survey periods one and two, but decreased significantly in survey period three, when expressed per day (p less than 0.002), per MJ (p less than 0.003), or per kg (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1991

The Drosophila dorsal-ventral patterning gene tolloid is related to human bone morphogenetic protein 1.

Mutations in the Drosophila tolloid (tld) gene lead to a partial transformation of dorsal ectoderm into ventral ectoderm. The null phenotype of tld is similar to, but less severe than decapentaplegic (dpp), a TGF-beta family member required for the formation of all dorsal structures. We have cloned the tld locus by P element tagging. At the blastoderm stage, tld RNA is expressed dorsally, similar to that described for dpp. Analysis of a tld cDNA reveals three sequence motifs: an N terminal region of similarity to a metalloprotease, two EGF-like repeats, and five copies of a repeat found in human complement proteins C1r and C1s. tld sequence is 41% identical to human bone morphogenetic protein 1 (BMP-1); the closest members to dpp within the TGF-beta superfamily are BMP-2 and BMP-4, two other bone morphogenetic proteins. These findings suggest that these genes are members of a signal generating pathway that has been conserved between insects and mammals.

Amino Acid Sequence↗
PubMed1989

Dietary calcium, phytate, and zinc intakes and the calcium, phytate, and zinc molar ratios of the diets of a selected group of East African children.

Dietary zinc, calcium, and phytate intakes of 66 rural Malawian children aged 4-6 y were determined during three seasons on the basis of weighed food records and analyzed food composition data. Height and weight measurements were also recorded and hair samples were collected for zinc analysis. Seasonal daily zinc, calcium, and phytate intakes of females ranged from 6.2 +/- 1.7 to 6.8 +/- 2.1 mg (mean +/- SD), from 335 +/- 170 to 401 +/- 257 mg, and from 1621 +/- 660 to 1729 +/- 592 mg, respectively and, for males, 7.0 +/- 1.7 to 8.0 +/- 2.3 mg, 342 +/- 164 to 473 +/- 310 mg, and 1857 +/- 530 to 2161 +/- 684 mg, respectively. Cereals provided greater than 42% of dietary zinc. Seasonal mean molar ratios of phytate to Zn and Ca x phytate to Zn [per 1000 kcal (4.2 MJ)] and the median Ca to phytate molar ratio ranged from 24 to 27, 151 to 188 mmol/1000 kcal (4.2 MJ), and 3.1 to 3.4, respectively. Over 78% of the children consumed diets with phytate-to-Zn and Ca x phytate.Zn-1 . 1000 kcal-1 molar ratios above values suggested to jeopardize zinc status. Correlations between hair zinc, phytate-to-Zn, and Ca x phytate.Zn-1 . 1000 kcal-1 molar ratios suggest that high phytic acid intakes may compromise zinc status in these children.

Body Height↗
PubMed1989

The multivulva phenotype of certain Caenorhabditis elegans mutants results from defects in two functionally redundant pathways.

We previously identified Caenorhabditis elegans mutants in which certain of the six vulval precursor cells adopt fates normally expressed by other vulval precursor cells. These mutants define genes that appear to function in the response to an intercellular signal that induces vulval development. The multivulva (Muv) phenotype of one such mutant, CB1322, results from an interaction between two unlinked mutations, lin-8(n111) II and lin-9(n112) III. In this paper, we identify 18 new mutations, which are alleles of eight genes, that interact with either lin-8(n111) or lin-9(n112) to generate a Muv phenotype. None of these 20 mutations alone causes any vulval cell lineage defects. The "silent Muv" mutations fall into two classes; hermaphrodites carrying a mutation of each class are Muv, while hermaphrodites carrying two mutations of the same class have a wild-type vulval phenotype. Our results indicate that the Muv phenotype of these mutants results from defects in two functionally-redundant pathways, thereby demonstrating that redundancy can occur at the level of gene pathways as well as at the level of gene families.

Animals↗
PubMed1985

Identification and characterization of 22 genes that affect the vulval cell lineages of the nematode Caenorhabditis elegans.

Ninety-five mutants of the nematode Caenorhabditis elegans altered in the cell lineages of the vulva have been isolated on the basis of their displaying one of two phenotypes, Vulvaless or Multivulva. In Vulvaless mutants, which define 12 genes, no vulva is present. In Multivulva mutants, which define ten genes, one or more supernumerary vulva-like protrusions are located along the ventral side of the animal. A single recessive mutation is responsible for the phenotypes of most, but not all, of these strains. Fifteen of these 22 genes are represented by multiple alleles. We have shown by a variety of genetic criteria that mutations that result in a Vulvaless or Multivulva phenotype in six of the 22 genes most likely eliminate gene function. In addition, Vulvaless or Multivulva mutations in seven of the other genes most likely result in a partial reduction of gene function; the absence of the activity of any of these genes probably results in lethality or sterility. Our results suggest that we may have identified most, or all, genes of these two classes.

Animals↗