Tooth,chin, bone and body size correlations

Correlations of size of teeth, chin, bone and body were investigated in 118 males and 102 females of the Burlington Growth Centre. In the males, the mesiodistal widths of the mandibular lateral incisors and canines were independently related to the thickness of the cortex of the second metacarpal and to body weight. Bone cortex thickness was significantly related to metacarpal width in males and to body weight in females. Chin depth of the males was significantly related to bone width and to body height, and negatively related to tooth width when bone width or body weight was held constant in partial correlations. Bone width and length were significantly related to body height in both sexes.     

Heterochrony and allometry: the analysis of evolutionary change in ontogeny

The connection between development and evolution has become the focus of an increasing amount of research in recent years, and heterochrony has long been a key concept in this relation. Heterochrony is defined as evolutionary change in rates and timing of developmental processes; the dimension of time is therefore an essential part in studies of heterochrony. Over the past two decades, evolutionary biologists have used several methodological frameworks to analyse heterochrony, which differ substantially in the way they characterize evolutionary changes in ontogenies and in the resulting classification, although they mostly use the same terms. This review examines how these methods compare ancestral and descendant ontogenies, emphasizing their differences and the potential for contradictory results from analyses using different frameworks. One of the two principal methods uses a clock as a graphical display for comparisons of size, shape and age at a particular ontogenic stage, whereas the other characterizes a developmental process by its time of onset, rate, and time of cessation. The literature on human heterochrony provides particularly clear examples of how these differences produce apparent contradictions when applied to the same problem. Developmental biologists recently have extended the concept of heterochrony to the earliest stages of development and have applied it at the cellular and molecular scale. This extension brought considerations of developmental mechanisms and genetics into the study of heterochrony, which previously was based primarily on phenomenological characterizations of morphological change in ontogeny. Allometry is the pattern of covariation among several morphological traits or between measures of size and shape; unlike heterochrony, allometry does not deal with time explicitly. Two main approaches to the study of allometry are distinguished, which differ in the way they characterize organismal form. One approach defines shape as proportions among measurements, based on considerations of geometric similarity, whereas the other focuses on the covariation among measurements in ontogeny and evolution. Both are related conceptually and through the use of similar algebra. In addition, there are close connections between heterochrony and changes in allometric growth trajectories, although there is no one-to-one correspondence. These relationships and outline links between different analytical frameworks are discussed.     

The secular trend in human physical growth: a biological view

Nutritionists and anthropometric historians alike are familiar with the secular trend-height and weight in adults, and the rate of physical development in children, increasing since at least the mid 19th century. The social conditions which drive this trend are of interest to anthropometric historians, but the underlying biology is also important. Here the trends for height, weight and menarcheal age are summarised and contrasted. In Northern Europe, adult height has largely stabilised, and the age of menarche has also settled at around 13 years, while weight continues to increase due to obesity. The increase in height from one generation to the next occurs mainly in the first 2 years of life, due to increases in leg length. The height trend has lasted for 150 years or more, i.e. for six generations, because the rate of catch-up from one generation to the next is biologically constrained to avoid the cost of too rapid catch-up.     

Autocrine stimulation by insulin-like growth factor I is involved in the growth, tumorigenicity and chemoresistance of human esophageal carcinoma cells

Insulin-like growth factor I (IGF-I) receptor (IGF-IR)-mediated signals are known to be involved in cell growth and transformation and prevention of apoptosis. In this study, we demonstrated the coexpression of IGF-I and IGF-IR in human esophageal carcinoma tissues. We also demonstrated the IGF-I autocrine system in esophageal carcinoma cell lines. Both the CE48T/VGH and CE81T/VGH cell lines showed proliferative responses to IGF-I stimulation. Autokinase activity of IGF-IR in these cells can be triggered by the exogenous addition of IGF-I. In addition, an IGF-I peptide antagonist, JB1, specifically inhibited ligand-induced receptor autophosphorylation in a dose-dependent manner. Under serum-free conditions, JB1 also reduced the degree of IGF-IR phosphorylation and cell numbers. Furthermore, the addition of JB1 decreased the number of CE81T/VGH colonies formed in methyl cellulose agar and the size and the incidence of tumors which grew in mice with severe combined immunodeficiency. These results imply that an IGF-I autocrine system in human esophageal carcinoma cells could stimulate tumor growth. Finally, we found that IGF-I prevented the apoptosis of CE81T/VGH cells induced by chemotherapeutic drugs, such as cisplatin, 5-fluorouracil and camptothecin. Thus, interruption of IGF-IR function may provide a way to retard tumor growth and increase the sensitivity of esophageal carcinoma to chemotherapy.     

Insulin-Like Growth Factor I Receptor Binding in Brains of Alzheimer''s and Alcoholic Patients

Patients with chronic alcoholism and/or Alzheimer's disease show degenerative changes in the cerebral cortex and hippocampus. To investigate possible changes in insulin-like growth factor I receptor binding sites in brain tissue of patients with these pathological conditions, the number of 125I-insulin-like growth factor I binding sites was determined in tissues obtained from control patients and those with Alzheimer's and/or with a history of alcoholism. The four experimental groups examined consisted of patients from similar age groups. Postmortem histology and a clinical history were used for the diagnosis of Alzheimer's disease and alcoholism, respectively. Careful clinical records were kept concerning other variables such as immediate cause of death and medications administered before death. Specific binding of 125I-insulin-like growth factor I to homogenates prepared from cerebral cortex of Alzheimer's, alcoholic, alcoholic Alzheimer's, and age-matched control patients was similar, although Alzheimer's patients tended to have slightly higher binding values. No significant differences in insulin-like growth factor I binding in cerebral cortex were found with regard to age of patients, the interval between death and autopsy, and CNS-active medications. No statistical differences in 125I-insulin-like growth factor I binding were noted in hippocampal tissue from the four patient groups. Thus, human insulin-like growth factor I binding sites in cerebral cortex and hippocampus appear unaffected by several variables.     

Niche division and abundance: an evolutionary perspective

 In recent years, biodiversity has become an issue of broad academic interest, and its assessment and maintenance are now recognized as an important area of ecological research. While the concept of biodiversity encompasses, first and foremost, the total number of species co-occurring in a locality, it has increasingly been realized that information on the relative abundances of co-occurring species is also required for a better understanding of the patterns and dynamics of biodiversity. In many areas of ecological research, “abundance” constitutes a key variable that characterizes populations and communities. The relative abundances of species in natural communities reflect evolutionary and contemporary processes occurring on different spatiotemporal scales. The idea of niche apportionment has been developed to provide an integrated conceptual framework for the study of species abundance patterns in communities. This article reviews a number of important issues surrounding the concept of niche apportionment, including some aspects that have received very little or no consideration in previous ecological literature. The main emphasis here is on possible evolutionary implications and backgrounds. Further, as a universal factor which affects species abundance in one way or another, body size is highlighted and its relationship with abundance (“density–body-size relation”) is considered, referring in particular to a recent comprehensive analysis of freshwater benthic data. Consideration of this and other studies has led to the formulation of the biomass equivalence rule, that suggests the independence of the biomass measure of abundance from body size, which strengthens the logical basis of niche apportionment models. It is suggested that, compared with Hubbell's neutral theory of biodiversity, niche apportionment with the biomass equivalence rule represents a conceptually more sound and widely applicable approach to elucidating species abundance patterns. Received: February 4, 2002 / Accepted: October 25, 2002 Correspondence to:M. Tokeshi     

Tooth size and morphology in a recent Australian Aboriginal population from Broadbeach,South East Queensland

Odontometric and morphologic observations were made of the dentition of skeletal remains of Australian aborigines from Boradbeach, S.E. Queensland. Tooth size, especially of the molars, was found to be significantly larger than that reported for other recent Aboriginal populations. Tooth morphology also differed, with a higher frequency of five cusped second molars, and a lower frequency of shoveling and Carabelli's cusp than previously reported as typical of Australian aborigines.     

Evidence for an Insulin-Like Growth Factor Autocrine-Paracrine System in the Retinal Photoreceptor-Pigment Epithelial Cell Complex

The interphotoreceptor matrix (IPM), lying between retinal photoreceptor and pigment epithelial (RPE) cells, contains insulin-like growth factor I (IGF-I) immunoreactivity that co-elutes with authentic human IGF-I in HPLC analyses. Cultured human RPE cells synthesize and release IGF-I, raising the possibility that the RPE serves as a source of IPM IGF-I in vivo. Photoreceptor rod outer segments and cultured monkey RPE cells express specific IGF-I receptors with alpha-subunits of 120 and 138 kDa, respectively. They thus appear to be of the "brain" (in photoreceptors) and "peripheral" (in RPE cells) receptor subtypes. Additionally, the IPM contains high levels of an IGF binding protein (IGF-BP) that specifically binds IGF-I and IGF-II. The IPM-BP is visualized as a single radiographic band by both ligand blot and affinity cross-linking procedures. With enzymes specific for removing N- and O-linked oligosaccharides, the IPM-BP was found to contain O- but not N-linked glycosylated side chains. The distinctive size and glycosylation pattern of the IPM-BP indicate that it is not derived from the vitreous or serum but instead is synthesized locally. The presence of IGF-I and IGF-BP in the IPM, together with the presence of IGF-I receptors on both photoreceptor and RPE cells, suggests the presence of an outer retina autocrine-paracrine system.     

Glucose, Insulin, and Insulin-Like Growth Factor I Regulate the Glycogen Content of Astroglia-Rich Primary Cultures

The glycogen content of astroglia-rich primary cultures derived from the brains of newborn rats depends on the concentration of glucose in the culture medium. After administration of culture medium lacking glucose, the glycogen content decreases with a half-time of 7 min. Readdition of glucose results in replenishment of the glycogen stores within 2-3 h, but fully only if glucose is present in a concentration of at least 4 mM. Insulin, or the more potent insulin-like growth factor I, increases the content of glycogen approximately 1.7-fold, with the half-maximal effects being attained at concentrations of 10 and 0.5 nM, respectively. These results suggest that (a) glucose or a metabolite of it and (b) insulin-like growth factor I or a closely related peptide, but not insulin, are likely to be physiological regulators of the level of glycogen in astrocytes.     

Squamate hatchling size and the evolutionary causes of negative offspring size allometry

Although fecundity selection is ubiquitous, in an overwhelming majority of animal lineages, small species produce smaller number of offspring per clutch. In this context, egg, hatchling and neonate sizes are absolutely larger, but smaller relative to adult body size in larger species. The evolutionary causes of this widespread phenomenon are not fully explored. The negative offspring size allometry can result from processes limiting maximal egg/offspring size forcing larger species to produce relatively smaller offspring (‘upper limit’), or from a limit on minimal egg/offspring size forcing smaller species to produce relatively larger offspring (‘lower limit’). Several reptile lineages have invariant clutch sizes, where females always lay either one or two eggs per clutch. These lineages offer an interesting perspective on the general evolutionary forces driving negative offspring size allometry, because an important selective factor, fecundity selection in a single clutch, is eliminated here. Under the upper limit hypotheses, large offspring should be selected against in lineages with invariant clutch sizes as well, and these lineages should therefore exhibit the same, or shallower, offspring size allometry as lineages with variable clutch size. On the other hand, the lower limit hypotheses would allow lineages with invariant clutch sizes to have steeper offspring size allometries. Using an extensive data set on the hatchling and female sizes of > 1800 species of squamates, we document that negative offspring size allometry is widespread in lizards and snakes with variable clutch sizes and that some lineages with invariant clutch sizes have unusually steep offspring size allometries. These findings suggest that the negative offspring size allometry is driven by a constraint on minimal offspring size, which scales with a negative allometry.     

The size–grain hypothesis and interspecific scaling in ants

1. The size–grain hypothesis maintains that as terrestrial walking organisms decrease in size, their environment becomes less planar and more rugose. The benefits of long legs (efficient, speedy movement over a planar environment) may thus decrease with smaller body size, while the costs (larger cross-sectional area limiting access to the interstitial environment) are enhanced.
2. A prediction from this hypothesis – that leg size should increase proportionately with body mass – is examined. Ants are among the smallest walking animals and extend the size gradient five orders of magnitude beyond the traditional 'mouse to elephant' curve. The mass of 135 species of worker ants spans 3·7 orders of magnitude (0·008–53 mg). Larger ants tended to be slimmer and longer legged. Ant subfamilies varied in their scaling relationships, but four out of five showed a positive allometry for hind leg length ( b > 0·33). Mammals, in contrast, show isometry for leg length over six orders of magnitude.
3. It is suggested that ants make a transition from living in an interstitial environment when small to a planar environment when large, a habit continued by most terrestrial mammals. Head length and pronotum width are robust estimators of mass in ants.     

人胰岛素生长因子Ⅰ基因的人工合成,克隆及其表达

采用固相亚磷酸三脂法,化学合成了人胰岛样生长因子Ｉ结构基因的两个１２９聚体长单链ＤＮＡ片段,通过其中的２３ｂｐ互补配对和Ｋｌｅｎｏｗ酶酶促补齐成为ＩＧＦ－Ｉ中进行ＤＮＡ全序列测定分析及寡核苷酸引导的定向点空变校正,获得了人工合成的ＩＧＦ－Ｉ结构基因。进一步分别重组构建了在Ｐｌａｃ和ＰＬＰｒｏｍｏｔｅｒ控制下的人工合成ＩＧＦ－Ｉ基因表达质粒ＰＨＭ５９０和ＰＢＬＥ０１１,在大肠杆菌中进行了表达研究。经     

The origin of allometric scaling laws in biology

The empirical rules relating metabolic rate and body size are described in terms of (i) a scaling exponent, which refers to the ratio of the fractional change in metabolic rate to a change in body size, (ii) a proportionality constant, which describes the rate of energy expenditure in an organism of unit mass. This article integrates the chemiosmotic theory of energy transduction with the methods of quantum statistics to propose a molecular mechanism which, in sharp contrast to competing models, explains both the variation in scaling exponents and the taxon-specific differences in proportionality constants. The new model is universal in the sense that it applies to unicellular organisms, plants and animals.     

Conserved ontogeny and allometric scaling of resource acquisition and allocation in the Daphniidae

Life histories vary widely among taxa, but within phylogenetic groups there may be a fundamental framework around which trait variation is organized, perhaps as a consequence of lineage-specific developmental constraints. In organisms with indeterminate growth, there is an ongoing problem of optimally allocating resources between growth and reproduction, and that allocation decision may manifest itself through allometric scaling. Previous work on freshwater zooplankton has shown that the ontogenetic pattern of resource allocation can be described by simple mathematical functions. An important component of understanding how such functions can explain life-history variation is to discover which parameters in these functions are robust, with respect to both resource availability and evolutionary diversification, and which parameters exhibit interspecific allometry. To shed light on these issues, detailed life table experiments were conducted on eight species in the family Daphniidae (Crustacea) at high and low levels of resources. Using data on growth, reproduction, and instar duration, the ontogeny of resource allocation to growth and reproduction could be described as functions that plateau at or shortly after the onset of maturity. To be sure that the results were not an artifact of phylogenetic structure, the parameters were tested in a phylogenetically controlled fashion. The results suggest a simple set of resource allocation rules for daphniids, whereby all species exhibit a similar form of ontogenetic change in allocation, and reach a plateau where approximately 94% of available resources are allocated to reproduction. The asymptotically maximal rate of net resources incorporated in growth and reproduction was positively related to size at maturity, whereas the rates of approach to plateaus (for both net resource assimilation and proportional allocation to reproduction) were negatively related to body size. Per-offspring investment was positively related to the square root of size at maturity. Using this approach, a wide range of interspecific variation in life-history features can be related to a single underlying trait, the size at first reproductive investment.     

Amino acid transport in a human neuroblastoma cell line is regulated by the type I insulin-like growth factor receptor

Insulin-like growth factor I (IGF-I) and IGF-II stimulate cancer cell proliferation via interaction with the type I IGF receptor (IGF-IR). We put forward the hypothesis that IGF-IR mediates cancer cell growth by regulating amino acid transport, both when sufficient nutrients are present and when key nutrients such as glutamine are in limited supply. We examined the effects of alphaIR3, the monoclonal antibody recognizing IGF-IR, on cell growth and amino acid transport across the cell membrane in a human neuroblastoma cell line, SK-N-SH. In the presence of alphaIR3 (2 micro/ml), cell proliferation was significantly attenuated in both control (2 mM glutamine) and glutamine-deprived (0 mM glutamine) groups. Glutamine deprivation resulted in significantly increased glutamate (system X(AG)(-)), MeAIB (system A), and leucine (system L) transport, which was blocked by alphaIR3. Glutamine (system ASC) and MeAIB transport was significantly decreased by alphaIR3 in the control group. Addition of alphaIR3 significantly decreased DNA and protein biosynthesis in both groups. Glutamine deprivation increased the IGF-IR protein on the cell surface. Our results suggest that activation of IGF-IR promotes neuroblastoma cell proliferation by regulating trans-membrane amino acid transport.     

一种新的胰岛素及生长因子促生长活性测定系统

ＧＲ２Ｈ６细胞是从小鼠乳腺癌细胞衍生来的成纤维细胞样细胞株。该细胞能在特定的无血清培养液中生长,我们发现在此无血清培养条件下,ＧＲ２Ｈ６细胞生长情况与胰岛素、表皮生长因子和类胰岛素生长因子－Ｉ的浓度有较好的相关性,根据细胞数目和ＤＮＡ总量的变化可定量测定胰岛素和上述生长因子对该细胞株的促生长作用。据此,本实验室建立了一种新的胰岛素与生长因子促生长活性测定系统。与已知的胰岛素和生长因子测活系统比较,     

Autoinhibition of the insulin-like growth factor I receptor by the juxtamembrane region

The juxtamembrane (JM) regions of several receptor tyrosine kinases are involved in autoinhibitory interactions that maintain the low basal activity of the receptors; mutations can give rise to constitutive kinase activity and signaling. In this report, we show that the JM region of the human insulin-like growth factor I receptor (IGF1R) plays a role in kinase regulation. We mutated JM residues that were conserved in this subfamily of receptor tyrosine kinases, and expressed and purified the cytoplasmic domains using the Sf9/baculovirus system. We show that a kinase-proximal mutation (Y957F) and (to a lesser extent) a mutation in the central part of the JM region (N947A) increase the autophosphorylation activity of the kinase. Steady-state kinetic measurements show the mutations cause an increase in V(max) for phosphorylation of peptide substrates. When the holoreceptors were expressed in fibroblasts derived from IGF1R-deficient mice, the Y957F mutation led to a large increase in basal and in IGF1-stimulated receptor autophosphorylation. Together, these data demonstrate that the JM region of IGF1R plays an important role in limiting the basal activity of the receptor.     

Ecosystem allometry: the scaling of nutrient stocks and primary productivity across plant communities

A principal challenge in ecology is to integrate physiological function (e.g. photosynthesis) across a collection of individuals (e.g. plants of different species) to understand the functioning of the entire ensemble (e.g. primary productivity). The control that organism size exerts over physiological and ecological function suggests that allometry could be a powerful tool for scaling ecological processes across levels of organization. Here we use individual plant allometries to predict how nutrient content and productivity scale with total plant biomass (phytomass) in whole plant communities. As predicted by our model, net primary productivity as well as whole community nitrogen and phosphorus content all scale allometrically with phytomass across diverse plant communities, from tropical forest to arctic tundra. Importantly, productivity data deviate quantitatively from the theoretically derived prediction, and nutrient productivity (production per unit nutrient) of terrestrial plant communities decreases systematically with increasing total phytomass. These results are consistent with the existence of pronounced competitive size hierarchies. The previously undocumented generality of these 'ecosystem allometries' and their basis in the structure and function of individual plants will likely provide a useful quantitative framework for research linking plant traits to ecosystem processes.