Actions and interactions of growth hormone and insulin-like growth factor-II: body and organ growth of transgenic mice

To characterize long-term actions and interactions of growth hormone (GH) and insulin-like growth factor-II (IGF-II) on postnatal body and organ growth, hemizygous phosphoenolpyruvate carboxykinase (PEPCK)-human IGF-II transgenic mice were crossed with hemizygous PEPCK-bovine GH transgenic mice. The latter are characterized by two-fold increased serum levels of IGF-I and exhibit markedly increased body, skeletal and organ growth. Four different genetic groups were obtained: mice harbouring the IGF-II transgene (I), the bGH transgene (B), or both transgenes (IB), and non- transgenic controls (C). These groups of mice have previously been studied for circulating IGF-I levels (Wolf et al., 1995a), whereas the present study deals with body and organ growth. Growth curves (week 3 to 12) were estimated by regression with linear and quadratic components of age on body weight and exhibited significantly (p < 0.001) greater linear coefficients in B and IB than in I and C mice. The linear coefficients of male I and C mice were significantly (p < 0.001) greater than those of their female counterparts, whereas this sex-related difference was absent in the bGH transgenic groups. The weights of internal organs as well as the weights of abdominal fat, skin and carcass were recorded from 3.5- to 8- month-old mice. In addition, organ weight-to-body weight-ratios (relative organ weights) were calculated. Except for the weight of abdominal fat, absolute organ weights were as a rule significantly greater in B and IB than in I and C mice. IGF-II overproduction as a tendency increased the weights of kidneys, adrenal glands, pancreas and uterus both in the absence and presence of the bGH transgene. Analysis of relative organ weights demonstrated significant (p < 0.05) effects of elevated IGF- II on the relative growth of kidneys (males and females) and adrenal glands (females), confirming our previous report on organ growth of PEPCK-IGF-II transgenic mice. In females, IGF-II and GH overproduction were additive in stimulating the growth of spleen and uterus, providing evidence for tissue-specific postnatal growth promoting effects by IGF-II in the presence of elevated IGF-I     

Scission of COPI and COPII Vesicles Is Independent of GTP Hydrolysis

Intracellular transport and maintenance of the endomembrane system in eukaryotes depends on formation and fusion of vesicular carriers. A seeming discrepancy exists in the literature about the basic mechanism in the scission of transport vesicles that depend on GTP‐binding proteins. Some reports describe that the scission of COP‐coated vesicles is dependent on GTP hydrolysis, whereas others found that GTP hydrolysis is not required. In order to investigate this pivotal mechanism in vesicle formation, we analyzed formation of COPI‐ and COPII‐coated vesicles utilizing semi‐intact cells. The small GTPases Sar1 and Arf1 together with their corresponding coat proteins, the Sec23/24 and Sec13/31 complexes for COPII and coatomer for COPI vesicles were required and sufficient to drive vesicle formation. Both types of vesicles were efficiently generated when GTP hydrolysis was blocked either by utilizing the poorly hydrolyzable GTP analogs GTPγS and GMP‐PNP, or with constitutively active mutants of the small GTPases. Thus, GTP hydrolysis is not required for the formation and release of COP vesicles.     

Shear Viscosity Investigation on Mango Juice with High Frequency Longitudinal Ultrasonic Waves and Rotational Viscosimetry

Ultrasonic velocity and attenuation measurements were performed on mango juices at 25 MHz in order to estimate longitudinal viscosity. Juices were extracted from fruits, removed periodically from fruit batches undergoing ripening for 3 weeks under controlled conditions. The correlation between longitudinal viscosity and apparent dynamic shear viscosity, obtained from flow tests, showed that up to 12–13 wt.% of Soluble Solids Content (SSC), the juices presented a Newtonian behavior. In this case the relation between longitudinal viscosity measured by ultrasound and shear viscosity measured by flow tests was very simple leading to the conclusion that ultrasound could replace rotating viscosimeters for specific applications. Over this limit, the results were also clearly correlated but the correlation depended on the shear rate because of the shear thinning behavior of the juices certainly due to soluble pectins. The use of longitudinal ultrasonic waves as a tool for viscosity determination on large batches of samples is discussed at the end of this communication.     

Do diversity of plants,soil fungi and bacteria influence aggregate stability on ultramafic Ferralsols? A metagenomic approach in a tropical hotspot of biodiversity

Plant and Soil - Understanding how soil aggregate stability (MWD) is influenced by microbial diversity and abundance can be crucial for ecological restoration in severely disturbed areas. We...     

Estimating Ecosystem Metabolism to Entire River Networks

Ecosystems - River ecosystem metabolism (REM) is a promising cost-effective measure of ecosystem functioning, as it integrates many different ecosystem processes and is affected by both rapid...     

Soil bio- and eco-engineering in China: past experience and future priorities

China has the world's longest history of soil bioengineering, with the first mention of giant fascines to control torrential floodwaters dating from over 2000 BC. However, soil degradation on steep slopes has accelerated hugely over the last 50 years, due to poor farming practice, deforestation, road and dam construction. The central government has therefore devised a series of major programs to reduce the exploitation of forest resources (Natural Forest Protection Program – NFPP) and to rehabilitate steep slopes by encouraging the conversion of cropland to forest and orchards (Sloping Land Conversion Program – SLCP). In this review, we define soil bio- and eco-engineering and examine China's past experience in both domains. We focus on case studies whereby vegetation has been used in conjunction with civil engineering to prevent landslides in Hong Kong and the social and practical aspects of planting on steep slopes to conserve soil on a large-scale in mainland China. The successes and failures of tree planting and forest management in the NFPP and SLCP are discussed along with the priorities for future research and practical applications. This review introduces a special edition of the journal Ecological Engineering, whereby a selection of papers presented at the Second International Conference ‘Ground Bio- and Eco-engineering: The Use of Vegetation to Improve Slope Stability – ICGBE2’ held in Beijing, China, 14–18 July 2008, are published. This congress joined together scientists and practitioners with the aim of discussing new theory, methods and applications for using vegetation to fix soil on steep slopes prone to landslides and erosion. In this review, we consider the key points from the conference and place them in the context of managing and restoring degraded slopes in China, one of the world's most pertinent study sites.     

Root anchorage of inner and edge trees in stands of Maritime pine (<Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait.) growing in different podzolic soil conditions

Static winching tests were carried out in order to determine the mechanical resistance of Maritime pine to overturning. The tested stands were selected according to podzolic soil conditions: wet Lande, characterised by a shallow ground water table and a hard pan horizon, and dry Lande, with a deeper ground water table and a hard pan absent or broken up. As this soil horizon limits the vertical growth of tree roots, anchorage resistance was investigated with regards to the presence or absence of a hard pan underneath each tree. To determine if mechanical behaviour differed within a stand, trees from inside the stand and edge trees at the border exposed to prevailing winds were also tested. The critical turning moment (TM_crit,total) at the base of the stem was positively related to the variable (H × DBH²) (H, total tree height; DBH, tree diameter). Linear regression analyses between TM_crit,total and (H × DBH²) showed that the presence of a hard pan had no significant effect on anchorage resistance in uprooted trees. Stem failure occurred for 82% of trees on dry Lande when (H × DBH²) < 1 m³. Moreover, stem failure type on dry Lande indicated that trees were better anchored. On soil with a hard pan, edge trees were found to be 20% more resistant to overturning than inner trees. Edge trees differed from inner trees in that the soil-root plate was two times larger and also possessed a larger surface area on the windward side.     

Influence of oxygen partial pressures on protein synthesis in feeding crabs

Many water-breathing animals have a strategy that consists of maintaining low blood PO2 values in a large range of water oxygenation level (4-40 kPa). This study examines the postprandial changes in O2 consumption, arterial blood PO2, and tissue protein synthesis in the shore crab Carcinus maenas in normoxic, O2-depleted, and O2-enriched waters to study the effects of this strategy on the O2 consumption and peptide bond formation after feeding. In normoxic water (21 kPa), the arterial PO2 was 1.1 kPa before feeding and 1.2 kPa 24 h later. In water with a PO2 of 3 kPa (arterial PO2 0.6 kPa), postprandial stimulation of protein synthesis and O2 consumption were blocked. The blockade was partial at a water PO2 of 4 kPa (arterial PO2 0.8 kPa). An increase in environmental PO2 (60 kPa, arterial PO2 10 kPa) resulted in an increase in protein synthesis compared with normoxic rates. It is concluded that the arterial PO2 spontaneously set in normoxic Carcinus limits the rates of protein synthesis. The rationale for such a strategy is discussed.     

Natriuretic peptide-dependent lipolysis in fat cells is a primate specificity

We have recently demonstrated that natriuretic peptides (NPs), which are known for regulation of blood pressure via membrane guanylyl cyclase (GC) receptors, are lipolytic in human adipose tissue. In this study, we compared the NP control of lipolysis in adipocytes from humans, nonhuman primates (macaques), rodents (rats, mice, hamsters), and nonrodent mammals (rabbits, dogs). Isolated adipocytes from these species were exposed to increasing concentrations of atrial NP (ANP) or isoproterenol (beta-adrenergic agonist). Although isoproterenol was lipolytic in all of the species, ANP only enhanced lipolysis in human and macaque adipocytes. In primate fat cells, NP-induced lipolysis involved a cGMP-dependent pathway. Binding studies and real-time quantitative PCR assays revealed that rat adipocytes expressed a higher density of NP receptors compared with humans but with a different subtype pattern of expression; type-A GC receptors predominate in human fat cells. This was also confirmed by the weak GC-activity stimulation and the reduced cGMP formation under ANP exposure in rat adipocytes compared with human fat cells. In conclusion, NP-induced lipolysis is a primate specificity, and adipocytes from ANP-nonresponsive species present a predominance of "clearance" receptors and very low expression of "biologically active" receptors.     

Activation of alpha2-adrenergic receptors blunts epinephrine-induced lipolysis in subcutaneous adipose tissue during a hyperinsulinemic euglycemic clamp in men

The aim of this study was to investigate whether hyperinsulinemia modifies adrenergic control of lipolysis, with particular attention paid to the involvement of antilipolytic alpha2-adrenergic receptors (AR). Eight healthy male subjects (age: 23.9 +/- 0.9 yr; body mass index: 23.8 +/- 1.9) were investigated during a 6-h euglycemichyperinsulinemic clamp and in control conditions. Before and during the clamp, the effect of graded perfusions of isoproterenol (0.1 and 1 microM) or epinephrine (1 and 10 microM) on the extracellular glycerol concentration in subcutaneous abdominal adipose tissue was evaluated by using the microdialysis method. Both isoproterenol and epinephrine induced a dose-dependent increase in extracellular glycerol concentration when infused for 60 min through the microdialysis probes before and during hours 3 and 6 of the clamp. The catecholamine-induced increase was significantly lower during the clamp than before it, with the inhibition being more pronounced in hour 6 of the clamp. Isoproterenol (1 microM)-induced lipolysis was reduced by 28 and 44% during hours 3 and 6 of the clamp, respectively, whereas the reduction of epinephrine (100 microM)-induced lipolysis was significantly greater (by 63 and 70%, P < 0.01 and P < 0.04, respectively) during the same time intervals. When epinephrine was infused in combination with 100 microM phentolamine (a nonselective alpha-AR antagonist), the inhibition of epinephrine (10 microM)-induced lipolysis was only of 19 and 40% during hours 3 and 6 of the clamp, respectively. The results demonstrate that, in situ, insulin counteracts the epinephrine-induced lipolysis in adipose tissue. The effect involves 1) reduction of lipolysis stimulation mediated by the beta-adrenergic pathway and 2) the antilipolytic component of epinephrine action mediated by alpha2-ARs.