Sex‐specific growth in chicks of the sexually dimorphic Black‐tailed Godwit

Sexual size dimorphism (SSD) is common in birds and has been linked to various selective forces. Nevertheless, the question of how and when the sexes start to differentiate from each other is poorly studied. This is a critical knowledge gap, as sex differences in growth may cause different responses to similar ecological conditions. In this study, we describe the sex‐specific growth – based on body mass and five morphometric measurements – of 56 captive Black‐tailed Godwit Limosa limosa limosa chicks raised under ad libitum food conditions, and conclude that all six growth curves are sex‐specific. Females are the larger sex in terms of body mass and skeletal body size. To test whether sex‐specific growth leads to sex‐specific susceptibility to environmental conditions, we compared the age‐specific sizes of male and female chicks in the wild with those of Black‐tailed Godwits reared in captivity. We then tested for a relationship between residual growth and relative hatching date, age, sex and habitat type in which the wild chicks were born. Early‐hatched chicks were relatively bigger and in better condition than late‐hatched chicks, but body condition and size were not affected by natal habitat type. Female chicks deviated more negatively from the sex‐specific growth curves than male chicks for body mass and total‐head length. This suggests that the growth of the larger females is more susceptible to limiting environmental conditions. On average, the deviations of wild chicks from the predicted growth curves were negative for all measurements, which suggests that conditions are limiting in the current agricultural landscape. We argue that in estimating growth curves for sexually dimorphic species, it is critical first to make accurate sex and age determinations.     

Serum concentrations of insulin‐like growth factor‐i and insulin‐like growth factor binding protein‐2 and ‐3 in eight hoofstock species

The somatotropic axis, which includes growth hormone, insulin‐like growth factor (IGF)‐I, and IGF binding proteins (IGFBP), is involved in the regulation of growth and metabolism. Measures of the somatotropic axis can be predictive of nutritional status and growth rate that can be utilized to identify nutritional status of individual animals. Before the somatotropic axis can be a predictive tool, concentrations of hormones of the somatotropic axis need to be established in healthy individuals. To begin to establish these data, we quantified IGF‐I, IGFBP‐2, and IGFBP‐3 in males and females of eight threatened hoofstock species at various ages. Opportunistic blood samples were collected from Bos javanicus (Java banteng), Tragelaphus eurycerus isaaci (bongo), Gazella dama ruficollis (addra gazelle), Taurotragus derbianus gigas (giant eland), Kobus megaceros (Nile lechwe), Hippotragus equines cottoni (roan antelope), Ceratotherium simum simum (white rhinoceros), and Elephas maximus (Asian elephant). Serum IGF‐I and IGFBPs were determined by radioimmunoassay and ligand blot, respectively. Generally, IGF‐I and IGFBP‐3 were greater in males, and IGFBP‐2 was greater in females. In banteng (P = 0.08) and male Nile lechwe (P<0.05), IGF‐I increased with age, but decreased in rhinoceros (P = 0.07) and female Nile lechwe (P<0.05). In banteng, IGFBP‐3 was greater (P<0.01) in males. In elephants (P<0.05) and antelope (P = 0.08), IGFBP‐2 were greater in females. Determination of concentrations of hormones in the somatotropic axis in healthy animals makes it possible to develop models that can identify the nutritional status of these threatened hoofstock species. Zoo Biol 30:275–284, 2011. © 2010 Wiley‐Liss, Inc.     

Fibroblast growth factor‐2/platelet‐derived growth factor enhances atherosclerotic plaque stability

Increased immature neovessels contribute to plaque growth and instability. Here, we investigated a method to establish functional and stable neovessel networks to increase plaque stability. Rabbits underwent aortic balloon injury and were divided into six groups: sham, vector and lentiviral transfection with vascular endothelial growth factor‐A (VEGF)‐A, fibroblast growth factor (FGF)‐2, platelet‐derived growth factor (PDGF)‐BB and FGF‐2 + PDGF‐BB. Lentivirus was percutaneously injected into the media‐adventitia of the abdominal aorta by intravascular ultrasound guidance, and plaque‐rupture rate, plaque‐vulnerability index and plaque neovessel density at the injection site were evaluated. Confocal microscopy, Prussian Blue assay, Evans Blue, immunofluorescence and transmission electron microscopy were used to assess neovessel function and pericyte coverage. To evaluate the effect of FGF‐2/PDGF‐BB on pericyte migration, we used the mesenchymal progenitor cell line 10T1/2 as an in vitro model. VEGF‐A‐ and FGF‐2‐overexpression increased the number of immature neovessels, which caused intraplaque haemorrhage and inflammatory cell infiltration, eventually resulting in the plaque vulnerability; however, FGF‐2/PDGF‐BB induced mature and functional neovessels, through increased neovessel pericyte coverage. Additionally, in vitro analysis of 10T1/2 cells revealed that FGF‐2/PDGF‐BB induced epsin‐2 expression and enhanced the VEGF receptor‐2 degradation, which negatively regulated pericyte function consistent with the in vivo data. These results showed that the combination of FGF‐2 and PDGF‐BB promoted the function and maturation of plaque neovessels, thereby representing a novel potential treatment strategy for vulnerable plaques.     

Effects of age‐based movement on the estimation of growth assuming random‐at‐age or random‐at‐length data

Simulation methods were used to generate paired data from a simulated population that included the age‐based process of movement and the length‐based process of gear selection. The age‐based process caused bias in the estimates of growth parameters assuming random at length, even when relatively few age classes were affected. Methods that assumed random at age were biased by the subsequent inclusion of the length‐based process of gear selection. Additional knowledge of the age structure of the sampled area is needed to ensure an unbiased estimate of the growth parameters when using the length‐conditional approach in the presence of age‐based movement. Estimates of the variability in the length‐at‐age relationship were better estimated with the length‐conditional than the traditional method even when the assumptions of random at length were violated. Inclusion of paired observations of length and associated age inside the population dynamics model may be the most appropriate way of estimating growth.     

Continental‐scale tree‐ring‐based projection of Douglas‐fir growth: Testing the limits of space‐for‐time substitution

A central challenge in global change research is the projection of the future behavior of a system based upon past observations. Tree‐ring data have been used increasingly over the last decade to project tree growth and forest ecosystem vulnerability under future climate conditions. But how can the response of tree growth to past climate variation predict the future, when the future does not look like the past? Space‐for‐time substitution (SFTS) is one way to overcome the problem of extrapolation: the response at a given location in a warmer future is assumed to follow the response at a warmer location today. Here we evaluated an SFTS approach to projecting future growth of Douglas‐fir (Pseudotsuga menziesii), a species that occupies an exceptionally large environmental space in North America. We fit a hierarchical mixed‐effects model to capture ring‐width variability in response to spatial and temporal variation in climate. We found opposing gradients for productivity and climate sensitivity with highest growth rates and weakest response to interannual climate variation in the mesic coastal part of Douglas‐fir's range; narrower rings and stronger climate sensitivity occurred across the semi‐arid interior. Ring‐width response to spatial versus temporal temperature variation was opposite in sign, suggesting that spatial variation in productivity, caused by local adaptation and other slow processes, cannot be used to anticipate changes in productivity caused by rapid climate change. We thus substituted only climate sensitivities when projecting future tree growth. Growth declines were projected across much of Douglas‐fir's distribution, with largest relative decreases in the semiarid U.S. Interior West and smallest in the mesic Pacific Northwest. We further highlight the strengths of mixed‐effects modeling for reviving a conceptual cornerstone of dendroecology, Cook's 1987 aggregate growth model, and the great potential to use tree‐ring networks and results as a calibration target for next‐generation vegetation models.     

Hepatoma‐derived growth factor promotes growth and metastasis of hepatocellular carcinoma cells

We aimed to elucidate the effects of hepatoma‐derived growth factor (HDGF) on growth and metastasis of hepatocellular carcinoma (HCC) cells. Tissue microarrays with 236 HCC specimens and 18 extrahepatic metastases were utilized to detect the HDGF expression by immunohistochemistry. Meanwhile, HDGF expressions in HCC cell lines with different metastatic potentials were examined using immunofluorescence staining, real‐time PCR and western blotting. After HDGF silencing, the growth and metastatic potentials of HCC cells were evaluated by soft agar assay, invasion assay, together with tumorigenicity assay in nude mice. The gelatin zymography was performed by detecting MMP‐2 and MMP‐9 levels. Additionally, western blotting was conducted to determine the levels of total and phosphorylated ERK1/2, JNK, p38 and Akt. The results showed that HDGF was overexpressed in HCC metastasis tumour, and the expression increased with the differentiation degree of tumours (Grade I 44.0%, Grade II 48.4% and Grade III 65.6%). Consistently, HDGF levels were positively associated with the metastatic capability of HCC cells (MHCC97L < MHCC97H < HCCLM3). The growth and metastasis were suppressed by HDGF‐siRNA. Gelatinolytic activities were enhanced in the three metastatic HCC cell lines, but had no significant difference among them. The tumourigenicity and metastatic capability of HCCLM3 cells in nude mice were inhibited after silencing HDGF. Meanwhile, HDGF‐siRNA specifically suppressed the total and phosphorylated protein levels of ERK1/2, while not JNK, p38 and Akt. In conclusion, HDGF was overexpressed in HCC patients and cells, and HDGF might be closely correlated with HCC metastasis via regulating ERK signalling pathway. Copyright © 2016 John Wiley & Sons, Ltd.     

Non‐exponential growth of Mycobacterium leprae Thai‐53 strain cultured in vitro

In this study, attempts were made to culture this bacterium in media supplemented with a variety of biological materials to determine why cultivation of Mycobacterium leprae in vitro has not this far been successful. A slight increase in the number of cells in medium supplemented with human blood plasma and an extract of nude mouse tissue as observed after more than 3 months of cultivation at 30 °C. To ascertain whether this increase was real growth, the growth was analyzed by droplet digital PCR, which showed a slow increase in the copy number of cell‐associated DNA and the release of a large amount of DNA into the culture medium from bacterial cells during cultivation. These results were supported by electron microscopic examination of M. leprae in infected mouse tissues, which showed that most of the replicated bacteria had degenerated and only a few cells survived. Based on these results, it was postulated that many of the replicated cells degenerate during M. leprae growth and that only a few cells remain to participate in the next growth stage. This means that, unlike other cultivable bacteria, the growth of M. leprae is not exponential and the number of cells therefore increase extremely slowly. Thus, accurate judging of the success of M. leprae cultivation requires observation of growth over a long period of time and careful measurement of the increase in number of viable cells.     

Density‐dependent and density‐independent growth in a population of juvenile sea‐trout,Salmo trutta,assessed using long‐term data from a small stream in Northwest England

相似文献   

A growth‐rate composition formula for the growth of E. coli on co‐utilized carbon substrates

When bacteria are cultured in medium with multiple carbon substrates, they frequently consume these substrates simultaneously. Building on recent advances in the understanding of metabolic coordination exhibited by Escherichia coli cells through cAMP‐Crp signaling, we show that this signaling system responds to the total carbon‐uptake flux when substrates are co‐utilized and derive a mathematical formula that accurately predicts the resulting growth rate, based only on the growth rates on individual substrates.     

miRNA‐210‐3p regulates trophoblast proliferation and invasiveness through fibroblast growth factor 1 in selective intrauterine growth restriction

Selective intrauterine growth restriction (sIUGR), which affects approximately 10%‐15% of monochorionic (MC) twin pregnancies, is highly associated with intrauterine foetal death and neurological impairment in both twins. Data suggest that unequal sharing of the single placenta is the main contributor to birth weight discordance. While MC twins and their placenta derive from a single zygote and harbour almost identical genetic material, the underlying mechanisms of phenotypic discrepancies in MC twins remain unclear. MicroRNAs are small non‐coding RNA molecules that regulate gene expression but do not change the DNA sequence. Our preliminary study showed that microRNA‐210‐3p (miR‐210‐3p) was significantly upregulated in the placental share of the smaller sIUGR twin. Here, we investigate the potential role of miR‐210‐3p in placental dysplasia, which generally results from dysfunction of trophoblast cells. Functional analysis revealed that miR‐210‐3p, induced by hypoxia‐inducible factor 1α (HIF1α) under hypoxic conditions, suppressed the proliferation and invasiveness of trophoblast cell lines. Further RNA sequencing analysis and luciferase reporter assays were performed, revealing that fibroblast growth factor 1 (FGF1) is an influential target gene of miR‐210‐3p. Moreover, correlations among miR‐210‐3p levels, HIF1α and FGF1 expression and the smaller placental share were validated in sIUGR specimens. These findings suggest that upregulation of miR‐210‐3p may contribute to impaired placentation of the smaller twin by decreasing FGF1 expression in sIUGR.     

Cell wall and cell growth characteristics of giant‐celled algae

Because of their large sizes and simple shapes, giant‐celled algae have been used to study how the structural and mechanical properties of cell walls influence cell growth. Here we review known relationships between cell wall and cell growth properties that are characteristic of three representative taxa of giant‐celled algae, namely, Valonia ventricosa, internodal cells of characean algae, and Vaucheria frigida. Tip‐growing cells of the genus Vaucheria differ from cells undergoing diffuse growth in V. ventricosa and characean algae in terms of their basic architectures (non‐lamellate vs. multilamellate) and their dependence upon pH and Ca²⁺ for cell wall extensibility. To further understand the mechanisms controlling cell growth by cell walls, comparative analyses of cell wall structures and/or associated growth modes will be useful. The giant‐celled algae potentially serve as good models for such investigations because of their wide variety of developmental processes and cell shapes exhibited.     

Targeted high‐throughput growth hormone 1 gene sequencing reveals high within‐breed genetic diversity in South African goats

This study assessed the genetic diversity in the growth hormone 1 gene (GH1) within and between South African goat breeds. Polymerase chain reaction‐targeted gene amplification together with Illumina MiSeq next‐generation sequencing (NGS) was used to generate the full length (2.54 kb) of the growth hormone 1 gene and screen for SNPs in the South African Boer (SAB) (n = 17), Tankwa (n = 15) and South African village (n = 35) goat populations. A range of 27–58 SNPs per population were observed. Mutations resulting in amino acid changes were observed at exons 2 and 5. Higher within‐breed diversity of 97.37% was observed within the population category consisting of SA village ecotypes and the Tankwa goats. Highest pairwise F_ST values ranging from 0.148 to 0.356 were observed between the SAB and both the South African village and Tankwa feral goat populations. Phylogenetic analysis indicated nine genetic clusters, which reflected close relationships between the South African populations and the other international breeds with the exception of the Italian Sarda breeds. Results imply greater potential for within‐population selection programs, particularly with SA village goats.     

Choosing the right sigmoid growth function using the unified‐models approach

Growth of the young is an important part of the life history in birds. However, modelling methods have paid little attention to the choice of regression model used to describe its pattern. The aim of this study was to evaluate whether a single sigmoid model with an upper asymptote could describe avian growth adequately. We compared unified versions of five growth models of the Richards family (the four‐parameter U‐Richards and the three‐parameter U‐logistic, U‐Gompertz, U‐Bertalanffy and U4‐models) for three traits (body mass, tarsus‐length and wing‐length) for 50 passerine species, including species with varied morphologies and life histories. The U‐family models exhibit a unified set of parameters for all models. The four‐parameter U‐Richards model proved a good choice for fitting growth curves to various traits – its extra d‐parameter allows for a flexible placement of the inflection point. Which of the three‐parameter U‐models was the best performing varied greatly between species and between traits, as each three‐parameter model had a different fixed relative inflection value (fraction of the upper asymptote), implying a different growth pattern. Fixing the asymptotes to averages for adult trait value generally shifted the model preference towards one with lower relative inflection values. Our results illustrate an overlooked difficulty in the analysis of organismal growth, namely, that a single traditional three‐parameter model does not suit all growth data. This is mostly due to differences in inflection placement. Moreover, some biometric traits require more attention when estimating growth rates and other growth‐curve characteristics. We recommend fitting either several three‐parameter models from the U‐family, where the parameters are comparable between models, or only the U‐Richards model.     

Sympathetic neurons synthesize and secrete pro‐nerve growth factor protein

Postmitotic sympathetic neuronal survival is dependent upon nerve growth factor (NGF) provided by peripheral targets, and this dependency serves as a central tenet of the neurotrophic hypothesis. In some other systems, NGF has been shown to play an autocrine role, although the pervasiveness and significance of this phenomenon within the nervous system remain unclear. We show here that rat sympathetic neurons synthesize and secrete NGF. NGF mRNA is expressed in nearly half of superior cervical ganglion sympathetic neurons at embryonic day 17, rising to over 90% in the early postnatal period, and declining in the adult. Neuronal immunoreactivity is reduced when retrograde transport is interrupted by axotomy, but persists in a subpopulation of neurons despite diminished mRNA expression, suggesting that intrinsic protein synthesis occurs. Cultured neonatal neurons express NGF mRNA, which is maintained even when they are undergoing apoptosis. To determine which NGF isoforms are secreted, we performed metabolic labeling and immunoprecipitation of NGF‐immunoreactive proteins synthesized by cultured NGF‐dependent and ‐independent neurons. Conditioned medium contained high molecular weight NGF precursor proteins, which varied depending upon the state of NGF dependence. Mature NGF was undetectable by these methods. High molecular weight NGF isoforms were also detected in ganglion homogenates, and persisted at diminished levels following axotomy. We conclude that sympathetic neurons express NGF mRNA, and synthesize and secrete pro‐NGF protein. These findings suggest that a potential NGF‐sympathetic neuron autocrine loop may exist in this prototypic target‐dependent system, but that the secreted forms of this neurotrophin apparently do not support neuronal survival. © 2003 Wiley Periodicals, Inc. J Neurobiol 38–53, 2003     

Old‐growth forests buffer climate‐sensitive bird populations from warming

Aim

Habitat loss and climate change constitute two of the greatest threats to biodiversity worldwide, and theory predicts that these factors may act synergistically to affect population trajectories. Recent evidence indicates that structurally complex old‐growth forest can be cooler than other forest types during spring and summer months, thereby offering potential to buffer populations from negative effects of warming. Old growth may also have higher food and nest‐site availability for certain species, which could have disproportionate fitness benefits as species approach their thermal limits.

Location

Pacific Northwestern United States.

Methods

We predicted that negative effects of climate change on 30‐year population trends of old‐growth‐associated birds should be dampened in landscapes with high proportions of old‐growth forest. We modelled population trends from Breeding Bird Survey data for 13 species as a function of temperature change and proportion old‐growth forest.

Results

We found a significant negative effect of summer warming on only two species. However, in both of these species, this relationship between warming and population decline was not only reduced but reversed, in old‐growth‐dominated landscapes. Across all 13 species, evidence for a buffering effect of old‐growth forest increased with the degree to which species were negatively influenced by summer warming.

Main conclusions

These findings suggest that old‐growth forests may buffer the negative effects of climate change for those species that are most sensitive to temperature increases. Our study highlights a mechanism whereby management strategies to curb degradation and loss of old‐growth forests—in addition to protecting habitat—could enhance biodiversity persistence in the face of climate warming.

     

Heterochrony and post‐natal growth in mammals – an examination of growth plates in limbs

Mammals display a broad spectrum of limb specializations coupled with different locomotor strategies and habitat occupation. This anatomical diversity reflects different patterns of development and growth, including the timing of epiphyseal growth plate closure in the long bones of the skeleton. We investigated the sequence of union in 15 growth plates in the limbs of about 400 specimens, representing 58 mammalian species: 34 placentals, 23 marsupials and one monotreme. We found a common general pattern of growth plate closure sequence, but one that is universal neither between species nor in higher‐order taxa. Locomotor habitat has no detectable correlation with the growth plate closure sequence, but observed patterns indicate that growth plate closure sequence is determined more strongly through phylogenetic factors. For example, the girdle elements (acetabulum and coracoid process) always ossify first in marsupials, whereas the distal humerus is fused before the girdle elements in some placentals. We also found that heterochronic shifts (changes in timing) in the growth plate closure sequence of marsupials occur with a higher rate than in placentals. This presents a contrast with the more limited variation in timing and morphospace occupation typical for marsupial development. Moreover, unlike placentals, marsupials maintain many epiphyses separated throughout life. However, as complete union of all epiphyseal growth plates is recorded in monotremes, the marsupial condition might represent the derived state.     

Sodium 5,6‐benzylidene‐L‐ascorbate induces oxidative stress,autophagy, and growth arrest in human colon cancer HT‐29 cells

Our previous studies have demonstrated the oxidative stress properties of sodium ascorbate (SAA) and its benzaldehyde derivative (SBA) on cancer cell lines, but the molecular mechanisms mediating their cytotoxicity remain unclear. In this study, we treated human colon cancer HT‐29 cells with SAA and SBA, and found a significant exposure time‐dependent increase of cytotoxicity in both treatments, with a higher cytotoxicity for 24 h with SAA (IC₅₀ = 5 mM) than SBA (IC₅₀ = 10 mM). A short‐term treatment of cells with 10 mM SAA for 2 h revealed a destabilization of the lysosomes and subsequent induction of cell death, whereas 10 mM SBA triggered a remarkable production of reactive oxidative species, phosphorylation of survival kinase AKT, expression of cyclin kinase‐dependent inhibitor p21, and induction of transient growth arrest. The crucial role of p21 mediating this cytotoxicity was confirmed by isogenic derivatives of the human colon carcinoma HCT116 cell lines (p21^+/+ and p21^?/?), and immunoprecipitation studies with p21 antibody. The SAA cytotoxicity was blocked by co‐incubation with catalase, whereas the SBA cytotoxicity and its subsequent growth arrest were abolished by N‐acetyl‐L‐cysteine (NAC), but was not affected by PI3K phosphorylation inhibitor LY294002, or catalase, suggesting two separated oxidative stress pathways were mediated by these two ascorbates. In addition, neither active caspase 3 nor apoptotic bodies but autophagic vacuoles associated with increased LC3‐II were found in SBA‐treated HT‐29 cells; implicating that SBA induced AKT phosphorylation‐autophagy and p21‐growth arrest in colon cancer HT‐29 cells through an NAC‐inhibitable oxidative stress pathway. J. Cell. Biochem. 111: 412–424, 2010. © 2010 Wiley‐Liss, Inc.