Differences In Growth Potential Research Articles

Mechanisms of antagonism of Pseudomonas fluorescens EPS62e against Erwinia amylovora, the causal agent of fire blight.

Pseudomonas fluorescens EPS62e was selected during a screening procedure for its high efficacy in controlling infections by Erwinia amylovora, the causal agent of fire blight disease, on different plant materials. In field trials carried out in pear trees during bloom, EPS62e colonized flowers until the carrying capacity, providing a moderate efficacy of fire-blight control. The putative mechanisms of EPS62e antagonism against E. amylovora were studied. EPS62e did not produce antimicrobial compounds described in P. fluorescens species and only developed antagonism in King's B medium, where it produced siderophores. Interaction experiments in culture plate wells including a membrane filter, which physically separated the cultures, confirmed that inhibition of E. amylovora requires cell-to-cell contact. The spectrum of nutrient assimilation indicated that EPS62e used significantly more or different carbon sources than the pathogen. The maximum growth rate and affinity for nutrients in immature fruit extract were higher in EPS62e than in E. amylovora, but the cell yield was similar. The fitness of EPS62e and E. amylovora was studied upon inoculation in immature pear fruit wounds and hypanthia of intact flowers under controlled-environment conditions. When inoculated separately, EPS62e grew faster in flowers, whereas E. amylovora grew faster in fruit wounds because of its rapid spread to adjacent tissues. However, in preventive inoculations of EPS62e, subsequent growth of EPS101 was significantly inhibited. It is concluded that cell-to-cell interference as well as differences in growth potential and the spectrum and efficiency of nutrient use are mechanisms of antagonism of EPS62e against E. amylovora.

Within-field variation in grain yield, yield components and quality traits of two-row barley

SUMMARYRecent studies of precision cereal farming systems have documented large within-field and annual variation in grain yield and quality. The principal aim of the present study was to evaluate the degree of within- and between-field variation in biomass, yield, yield component structure and quality traits, such as grain protein of two-row barley (Hordeum vulgare L.), using crop samples collected from field patches of varying yield potential. Plant samples were collected from the fields of commercial farmers located in southern Finland in 2000 and 2001. Selection of low, intermediate and high yielding patches for crop sampling was based on aerial infrared colour images taken twice during the growing season. When stands were mature, plant samples from an area of 0·5 m2 were uprooted for yield component and quality analysis. Nitrogen accumulation prior to heading was strongly associated with biomass accumulation, indicating differences in growth potential of the different field patches. The principal yield determining trait in two-row barley was grain number/m2, whereas single grain weight (SGW) had a lesser effect on grain yield. The degree of variation in the quality parameters, namely protein and SGW, was not associated with grain yield. This suggests that within-field variation in yield potential does not determine heterogeneity of the grain yield in terms of grain weight or grain protein content.

The Deletion of NHR1 Region of the AML1-ETO Protein Significantly Decreases Its Ability To Promote Proliferation and Self-Renewal of Early Hematopoietic Cells in Culture.

Although the transcriptional product of the (8;21) chromosomal translocation, the AML1-ETO protein, has numerous well established effects on the behavior of human hematopoietic cells, the specific cellular pathways perturbed by it are only partly known. Recently AML1-ETO has been shown to bind E-proteins (members of the class I basic helix-loop-helix family) via its NHR1 (nervy homology region one) domain, thus causing a replacement of the co-activator p300/CBP complex by the co-repressor hystone deacytelase complexes and abrogating the E-protein induced transcriptional activation (Zhang et al, Science 2004). The removal of amino acids 93 to 189 from the NHR1 domain (the ΔNHR1 mutant form) has completely reversed this inhibitory effect, and thus we have studied the biological effects of this deletion.To assess the difference in self-renewal capacity between cells transduced with the full length and the ΔNHR1 forms of AML1-ETO, CD34+ cells were plated into methylcellulose culture medium. On days 14 and 28 myeloid and erythroid colonies were scored, and the cells harvested and re-plated. The scoring on day 14 showed no significant difference in either the overall number or the type of colonies, with both the full-length AML1-ETO and the ΔNHR1 mutant showing a decreased erythroid colony formation, thus indicating a preserved negative effect on hematopoietic cell differentiation. However, on days 28 and 42 cells expressing the full-length AML1-ETO scored a significantly higher number of colonies than cells expressing the ΔNHR1 mutant, whereas cells transduced with the empty MIGR1 vector were unable to form any colonies after second re-plating.To assess the difference in growth potential, we have plated cells containing each of the constructs in IMD medium supplemented with 20% BIT and cytokines (SCF, FLT-3L, IL-6, TPO). Following one week in culture the cells were harvested, counted and then serially re-plated for five weeks. We observed a significantly higher number of cells expressing the full-length AML1-ETO as compared to the ΔNHR1 mutant at each weekly time point. Cells growing in the liquid culture were also weekly re-plated into methylcellulose culture medium. In this assay the loss of NHR1 domain significantly diminished the ability of AML1-ETO to maintain colony-forming progenitors in culture. To assess the difference in transcriptional activity of the different constructs, we have measured the expression of p21, and several other potential AML1-ETO target genes, by Real Time PCR. The expression of p21 was increased 14-fold by the full-length AML1-ETO, but only 2-fold by the ΔNHR1 mutant.We conclude that partial deletion of the NHR1 lowers the self-renewal capacity of transduced hematopoietic cells, decreases the proliferative advantage conferred by AML1-ETO, undermines its ability to maintain colony-forming units, and affects the transcriptional activation of AML1-ETO target genes. As the loss of NHR1 abolishes the E-protein induced transcriptional activation without affecting the binding of AML1-ETO to DNA, our findings identify an additional mechanism of action for AML1-ETO, independent of its dominant-negative effect on AML1 target genes.

An absolute procedure to test the growth potential of medium and the influence of decreased oxygen tension in primary amniotic fluid cell cultures

For prenatal cytogenetic diagnosis, cell cultures should be maximally successful. When introducing a change in conditions, e.g. a new batch of medium, the growth potential of a culture is usually compared under both the new condition and the one already in use. Such a relative test is in principle subject to drift and may over time increasingly lead to rejection of new adequate conditions, c.q. good batches of medium. We therefore wanted to design an absolute test to assess the quality of a new condition for amniotic fluid (AF) in situ cell culturing. We tested batches of medium under sub-optimal (stress) conditions, expecting that differences in growth potential would thereby be more readily observed. In our stress test, we diluted the culture medium to the extent of achieving a 50% growth reduction. Thresholds for rejecting a new condition were empirically determined, based on the acceptance of a less than 1% probability of false rejection of a good condition. Testing three cultures per patient for ten patients, i.e. 30 cultures in total, in a medium diluted to 30% of the original concentration, showed that a minimal number of 23 successful cultures and an average number of three or more colonies per culture appeared as thresholds meeting our rejection criteria. Testing five different media resulted in the rejection of one. Using the same stress test to evaluate the effect of culturing under decreased oxygen tension showed that 2.5 and 5% oxygen tension caused a larger colony size. We designed a sensitive absolute test to assess the quality of culturing conditions for cells to be used in prenatal diagnosis in general and in particular to test the growth potential of different batches of culture medium.

The Evolution of Foot Morphology in Children Between 6 and 17 Years of Age: A Cross-Sectional Study Based on Footprints in a Mediterranean Population

Footprint evaluation is a widely used method for the determination of foot morphology, but its efficacy and validity are considered controversial. Dynamic footprints were obtained from both feet of 5,866 school-aged children (6-17 years old) to detect any foot changes during growth. The interpretation of the imprint was performed using a classification scheme consisting of 6 types of footprints. In this scheme, footprint types I and II represent the typical and intermediate high-arched foot, respectively. Types III and IV represent normal foot variants, while type V corresponds to the low-arched foot and type VI to the severe flat foot, the latter often encountered in pathological conditions. There was statistically significant difference (P<.05) in footprint-type frequencies between boys and girls of ages 7, 9, 11, 14, and 15, which probably indicates the difference in growth potential of the foot between sexes. The proportion of high- and low-arched foot types decreased with increasing age in both boys and girls. Even though critical changes of the foot are believed to occur during pre-school development, this study shows that considerable changes also take place during school age and until late adolescence.

Generation and characterization of HIV-1 clones chimeric for subtypes B and C nef

The impact of human immunodeficiency virus type 1 (HIV-1) Nef on viral infectivity was evaluated by characterization of chimeric clones. Chimera with respect to the nef gene were constructed between subtypes B and C, and monitored for their replication in human peripheral blood mononuclear cells. The parental clones used were pNL432 (subtype B) and pIndie-C1 (Indian subtype C), which show considerable sequence heterogeneity in nef and distinct viral growth phenotype. While an enhancing effect of Nef on viral infectivity was noted, no significant growth difference was observed between the parental and chimeric clones. The difference in growth potential of the two subtype clones was mainly ascribable to viral sequence(s) other than nef. Our results here clearly showed that HIV-1 Nef does not significantly affect the in vitro viral infectivity in natural target cells.

Cultures of ovarian surface epithelium from women with and without a hereditary predisposition to develop female adnexal carcinoma

Aim. Conflicting evidence exists on whether in vivo morphological characteristics can distinguish Ovarian Surface Epithelium (OSE) of ovaries obtained from women with and without a predisposition to develop female adnexal (ovarian and fallopian tube) carcinoma. This study aims to detect differences in growth potential and morphology that are maintained or specifically expressed in vitro. Study design. Ovarian surfaces were scraped to retrieve OSE cells from 56 women at hereditary high risk for female adnexal carcinoma, of whom 33 are BRCA1 and four are BRCA2 mutation carriers (Predisposed OSE, POSE) and from 26 women without such risk (Non Predisposed OSE, NPOSE). Number of passages and total cell yield until last passage, as well as morphology was compared between both groups. To confirm morphology, the expression of epithelial, mesothelial, and fibroblast markers was assessed. Results. Both POSE and NPOSE cultures displayed similar growth potential and morphology. The expression of epithelial markers cyto-keratins 7 and 8 was similar between both groups. Only in cultures in which cells did not uniformly exhibit these markers, the percentage of cells expressing these markers was significantly lower at last passage when compared to the initial culture. In these latter cultures, cells that were morphologically indistinguishable from fibroblasts were observed. Mesothelial marker calretinin was expressed in 75% of cells of both POSE and NPOSE cultures and correlates with cyto-keratins 7 and 8 expression. CA 125 expression was equally low in POSE and NPOSE cultures (4.3%). Fibroblast markers FSM and vimentin were expressed in 100% and collagen IV was expressed in 16% of cells in all cultures. Conclusion. OSE cells derived from women with a hereditary predisposition to develop female adnexal cancer possess similar in vitro characteristics as OSE from women without this predisposition. On basis of our results, it seems advisable to study only 100% cyto-keratins 7 and 8 positive OSE cultures, since contamination of fibroblasts in some primary OSE cultures cannot be ruled out.

Stock-Specific Growth and Length Frequency Bimodality in Brown Trout

The growth of three pure stocks and one hybrid stock of anadromous brown trout Salmo trutta—comprising 19 families and 15,000 individuals—was monitored under controlled conditions from hatching for a period of 16 months. Significant differences in growth were detected among the three pure stocks, and the hybrid stock outgrew its two parental stocks. Significant differences in family growth were also detected. Two of the stocks developed clear bimodal length frequency distributions, whereas the other two stocks displayed skewed or weakly bimodal length frequency distributions. The observed differences in growth among the stocks probably reflect genetic differences in growth potential. The pattern of growth and development of length frequency bimodality in the brown trout stocks reared in this study is similar to the pattern of growth and length frequency bimodality development in Atlantic salmon Salmo salar. We conclude that length frequency bimodality in anadromous brown trout is probably linked to the process of smoltification, as is the case for Atlantic salmon.

Differences in the somatotropic axis, in blood cortisol, insulin and thyroid hormone concentrations between two pig genotypes with markedly divergent growth rates and the effects of growth hormone treatment

AbstractThe intention of the current study was to gain more insight into the endocrine and molecular control mechanisms of growth in the pig. For this purpose various growth related parameters were determined in 4-month-old barrows of two extreme pig genotyes, the small, obese Göttingen Miniature (GM) and the large and lean German Landrace (DL). Mean growth hormone (GH) concentration, GH pulse frequency and GH pulse amplitude did not differ between breeds. Likewise, plasma IGF-1, thyroxine, tri-iodothyronine (T3) concentrations were similar in both breeds. However the plasma GH response (maximum level and area under curve) to a single i.v. injection of GHRH in DL was higher than in GM (P &lt; 0·05). Furthermore, basal plasma insulin and in particular plasma cortisol concentrations were higher in GM compared with DL pigs (P 0·05 and 0·01 respectively). Analysis of cortisol during 4-h frequent blood sampling indicated higher cortisol amplitudes in GM compared with DL (P ≤ 0·01). Specific bGH-binding to hepatic membrane preparations was not different between breeds and IGF-1 m RNA concentrations determined by reverse transcription-polymerase chain reaction in liver, m. semimenbranosus and m. longissimus dorsi were similar in both breeds. I.m. treatment with recombinant porcine somatotropin (rpST; 70 µg/kg live weight) over an 8-day period in contemporary barrows increased without any breed difference, plasma IGF-1, T3 and insulin concentrations and hepatic specific bGH-binding, but did not affect thyroxine or cortisol concentrations in plasma. IGF-1 gene expression was also elevated in liver and muscle tissues in rpST-treated animals without obvious breed effects. The observations underline the complexity of the hormonal and molecular control of growth and support the notion that differences in growth potential are the consequence of differences at various levels of the somatotropic axis and apparently relate to differences in other control systems of energy metabolism such as the pituitary adrenal axis or the endocrine pancreas as well.

Prey size of salmonid fishes in streams, lakes, and oceans

The growth rate of salmonid fishes is typically fastest in oceans, intermediate in lakes, and slowest in streams. We compiled literature data to test whether differences in the size of prey eaten by salmonids in the three habitats could account for these differences in growth rate (i.e., the prey-size hypothesis). In all three habitats, salmonid fishes exhibited ontogenetic niche shifts from feeding primarily on invertebrates when small to feeding on fishes when large. Contrary to the prey-size hypothesis, invertebrates eaten in streams were larger than those eaten in lakes or oceans, whereas fish eaten in oceans were smaller than those eaten in streams or lakes. Consistent with the prey-size hypothesis, salmonids began eating fish at a smaller size in oceans (8 cm) than in lakes (15 cm) or streams (27 cm). However, the size at which salmonids became predominantly piscivorous (31 cm) did not differ significantly between habitats. We suggest that the difference in growth potential between the three habitats is partly related to the size at which fish first enter the diet.

Prey size of salmonid fishes in streams, lakes, and oceans

The growth rate of salmonid fishes is typically fastest in oceans, intermediate in lakes, and slowest in streams. We compiled literature data to test whether differences in the size of prey eaten by salmonids in the three habitats could account for these differences in growth rate (i.e., the prey-size hypothesis). In all three habitats, salmonid fishes exhibited ontogenetic niche shifts from feeding primarily on invertebrates when small to feeding on fishes when large. Contrary to the prey-size hypothesis, invertebrates eaten in streams were larger than those eaten in lakes or oceans, whereas fish eaten in oceans were smaller than those eaten in streams or lakes. Consistent with the prey-size hypothesis, salmonids began eating fish at a smaller size in oceans (8 cm) than in lakes (15 cm) or streams (27 cm). However, the size at which salmonids became predominantly piscivorous (31 cm) did not differ significantly between habitats. We suggest that the difference in growth potential between the three habitats is partly related to the size at which fish first enter the diet.

International variations in intrauterine growth

International variations in intrauterine growth have consistently been judged in terms of average birthweight, low birthweight or birthweight-for-gestational age criteria. Neither of these provide an appropriate assessment of fetal growth. Notwithstanding these limitations the available evidence indicates that variations in growth, both within and among populations, relate predominantly to differences in the prevalence of factors that restrain growth rather than to inherent differences in growth potential. The evidence also indicates that differences in the frequency of low weight-for-gestation among populations do not only reflect factors that restrict fetal growth. They are also intimately linked to variations in gestational age and to frequencies of preterm birth in particular. Hence, if weight-for-gestational standards are to become more informative and more universally applied than they have been so far, it may be useful to acknowledge their limitations more explicitly and simplify their implementation in a wider range of communities.

Effects of amount offered on the intake and selection of barley straw by growing cattle

AbstractA 28-day experiment with 12 9-month-old cattle (275 kg initial weight, M1), used a 2 × 2 arrangement of treatments to compare the effect of doubling the ad-libitum quantity of long barley straw offered daily (25 or 50 g dry matter (DM) per kg M1) and sex/genotype (Limousin × Friesian steers or Friesian heifers) on intake and selection. All animals received a protein concentrate at 20 g DM per kg M10·75per day. Prior to the experiment the cattle had grazed for 6 months and were given no pre-experimental change-over period. On day 1 animals were weighed (M1), allocated to treatment and penned individually. Animals were weighed on day 28 (M2). Doubling the amount offered did not affect straw intake (g DM per kg M3 per day; M3= mean of M1and M2) during days 22 to 28 (steers: 17·9, 17·2; heifers 14·3, 13·3; s.e. 0·50) but increased the proportion (g DM per kg DM offered) refused (steers: 258, 635; heifers: 412, 721; s.e. 22). During days 22 to 28, at each level of offer (25, 50), refused straw contained (g DM per kg DM) less leaf-plus-sheath than offered straw (25 g steers: 251, 430, s.e. 16·7; 50 g steers: 393, 450, s.e. 19·7; 25 g heifers: 304, 420, s.e. 7·2; 50 g heifers: 405, 446, s.e. 9·6). The sex/genotype effect on intake was attributed to differences in growth potential. Straw intakes increased significantly over the first 14 days, but there were no differences between days 15 to 21 and days 22 to 28. It is concluded that an excess-feeding strategy, involving a doubling of the ad libitum amount of barley straw offered did not result in growing cattle consuming more straw, in contrast to published results with sheep and goats. However, the cattle did show a limited ability to selectively consume leaf-plus-sheath in preference to stem but the improvement in diet digestible organic content (estimated in vitro) was presumably insufficient to stimulate intake.

Human Telomerase RNA Expression and MIB-1 (Ki-67) Proliferation Index Distinguish Hemangioblastomas From Metastatic Renal Cell Carcinomas

Hemangioblastomas are low-grade, capillary rich neoplasms of the cerebellum and spinal cord that can occur sporadically or in the setting of Von Hippel-Lindau syndrome. The present study analyzed the utility of proliferation potential in differentiating hemangioblastoma from RCC metastatic to the central nervous system using a MIB-1 (Ki-67) labeling index and assessment of expression of the RNA component of telomerase. Immunohistochemical analysis for epithelial membrane antigen (EMA) and MIB-1 was performed on paraffin-embedded sections of 27 hemangioblastomas and 5 RCC metastatic to the central nervous system. All but one hemangioblastoma demonstrated low or negative MIB-1 immunoreactivity, while 4 of 5 RCC metastases had moderate or high labeling indices. Telomerase RNA expression was assessed in 10 hemangioblastomas and in all 5 metastatic RCC by in situ hybridization. All 10 hemangioblastomas demonstrated a lack of expression of telomerase RNA, while all 5 metastatic RCCs showed moderate to strong expression. Our results suggest that the MIB-1 labeling index is useful in differentiating hemangioblastoma from metastatic RCC and assessment of telomerase expression can also provide novel information on the difference in growth potential of these tumors.

Human telomerase RNA expression and MIB-1 (Ki-67) proliferation index distinguish hemangioblastomas from metastatic renal cell carcinomas.

Hemangioblastomas are low-grade, capillary rich neoplasms of the cerebellum and spinal cord that can occur sporadically or in the setting of Von Hippel-Lindau syndrome. The present study analyzed the utility of proliferation potential in differentiating hemangioblastoma from RCC metastatic to the central nervous system using a MIB-1 (Ki-67) labeling index and assessment of expression of the RNA component of telomerase. Immunohistochemical analysis for epithelial membrane antigen (EMA) and MIB-1 was performed on paraffin-embedded sections of 27 hemangioblastomas and 5 RCC metastatic to the central nervous system. All but one hemangioblastoma demonstrated low or negative MIB-1 immunoreactivity, while 4 of 5 RCC metastases had moderate or high labeling indices. Telomerase RNA expression was assessed in 10 hemangioblastomas and in all 5 metastatic RCC by in Situ hybridization. All 10 hemangioblastomas demonstrated a lack of expression of telomerase RNA, while all 5 metastatic RCCs showed moderate to strong expression. Our results suggest that the MIB-1 labeling index is useful in differentiating hemangioblastoma from metastatic RCC and assessment of telomerase expression can also provide novel information on the difference in growth potential of these tumors.

Apoptosis in astrocytic neoplasms.

Apoptosis is a form of programmed cell death characterized by specific morphologic and biochemical properties. Tumorgenesis is the consequence not only of cell proliferation but also the loss of the ability to undergo apoptosis [2]. Bcl-2 is a protooncogene which has the ability to block apoptosis in many cell types. Astrocytic neoplasms are very aggressive tumors which many times fail to respond to surgery, radiation or chemotherapy. They frequently overexpress wild-type p53 which is associated with the expression of bcl-2, and thus they may have evolved a mechanism to subvert apoptosis and allow continued growth. We examined the apoptotic index in fifty-nine astrocytic tumors of various histological grades (Oncor ApopTag Plus In Situ Detection Kit) and compared this with the level of bcl-2 expression. Low grade astrocytomas (0.21 +/- 0.05; range 0.0-0.9) and anaplastic astrocytomas (0.27 +/- 0.13; range 0.0-2.6) had significantly less apoptosis than glioblastomas (0.70 +/- 0.13; range 0.0-2.1; Kruskal-Wallis test, P < or = 0.01). In contrast, bcl-2 expression was similar in all grades of astrocytic tumors and did not correlate with the apoptotic index. Cells of low grade and anaplastic astrocytomas are less likely to undergo apoptosis; however, this does not seem to be a direct consequence of the regulation of bcl-2 expression. The difference in growth potential despite differences in apoptotic index is likely to be attributed to differences in mitotic not apoptotic activity.

HIV-1 Env Glycoproteins from Two Series of Primary Isolates: Replication Phenotype and Immunogenicity

Seven envelope regions from two series of patient isolates have been molecularly cloned and analyzed for replication phenotypes and immunogenicity. Growth potential was analyzed forenvsequences substituted into an HIV-1-NL4-3 backbone (NL4-3/env recombinants). Immunogenicity studies were conducted on secreted monomeric (gp120) and oligomeric (gp140) forms of the Envs using Env-expressing plasmid DNAs for immunizations. Theenvregions of the patient isolates conferred a spectrum of replication kinetics and cytotropisms on the NL4-3/env recombinants. Both patient series included non-syncytium-inducing viruses with no ability to grow on T-cell lines, and highly syncytium inducing viruses which grew well on T-cell lines. These differences in growth potential did not correlate with the ability of the DNA-expressed Envs to raise antibody in rabbits. Rather, the relative immunogenicity of the Envs was patient and form specific. The Envs from patient 5 raised higher titers of antibody than the Envs from patient 6. For each primary Env, the gp120 form of the Env raised higher titers of antibody than the gp140 form. Thus, structural features of Env that affect replication do not necessarily affect the ability to raise antibody.

Percentiles of Modern Height Standards for Use in Historical Research

Percentiles of modern height standards are useful in historical research because children differ systematically in height by age, and differences in growth potential exist by gender and might exist across some ethnic groups. Modern height standards are needed to make relative comparisons of nutritional status in these circumstances. The standards are also used to assess progress or deprivation against a level that we know is attainable under good environmental circumstances. Historical researchers in need of modern height standards encounter several problems, including the choice of standards, manipulation of those standards to meet the requirements of historical data, and calculation of percentiles. Following a discussion of criteria used in selecting standards, which lead to the choice of NCHS heights as a reference, the paper gives percentiles calculated in line with the requirements of historical data. Results are given in centimeters and inches and by age at last birthday and age at nearest birthday.

Growth of five landlocked Arctic charr stocks under hatchery conditions

Growth dynamics of five stocks of Arctic charr, were compared from the fry stage in June 1986 until December 1987. Each stock originated from a different lake in Sweden: Hornavan; Nackten; Torron; Rensjon and Visjon. Hornavan charr reached the highest final mean weight (237 g), but they were not significantly heavier than Visjon charr (206 g). Growth of fish of the three remaining stocks was similar but less rapid. The superior growth performance of Hornavan charr was most pronounced during autumn. Coefficients of variation for individual size within stocks was between 30 and 54%, with Hornavan and Nackten charr displaying least variability. Charr from Lake Visjon had a significantly lower proportion of mature males (6%) than the other stocks (19–29%) at the end of the experiment. The results demonstrate that differences in growth potential exist between stocks of charr, and these differences may be related to differential seasonal rhythms in growth. Variations in early growth, size distributions and sexual maturation seemed to be subordinate factors affecting overall growth performance.

Early childhood growth of Chachi Amerindians and Afro-Ecuadorians in Northwest Ecuador.

This study compares the growth of Chachi Amerindian and Afro-Ecuadorian children living in the tropical forest of northwest Ecuador. Measurements of height and weight were taken on 148 Chachi and 148 Afro-Ecuadorian children under 5 years of age. Triceps and subscapular skinfolds, arm circumference, chest circumference, and sitting height were measured on a subsample of children. Socioeconomic information was collected from the households of 145 children, and a general socioeconomic index was derived. Afro-Ecuadorian children are substantially taller than Chachi children, with significant differences in height for age z-scores in most age groups. On the other hand, Chachi children tend to have greater weight for height z-scores, with significant differences in some age groups. The greater weight for height of Chachi children may be related to their larger trunks. Estimates of body composition suggest that Afro-Ecuadorian children may have somewhat better nutritional status than Chachi children, but this does not appear to fully account for the greater height of Afro-Ecuadorian children. The socioeconomic index is positively correlated with all anthropometric dimensions, but even after controlling for the socioeconomic index, Afro-Ecuadorian children are significantly taller than Chachi children. These findings raise the possibility of genetic differences in growth potential between the two groups. © 1996 Wiley-Liss, Inc.