Somatomedin-C stimulates somatostatin release to a maximum of 390 percent of basal release during short-term (20-minute) incubation of rat hypothalamus. It has no effect on basal or stimulated growth hormone release from primary cultures of rat adenohypophyseal cells during a 4-hour incubation, but inhibits stimulated release by more that 90 percent after 24 hours. These findings suggest that somatomedin-C participates in the growth hormone negative feedback loop with an immediate effect on hypothalamic somatostatin and a delayed effect on the anterior pituitary.

http://science.sciencemag.org/content/sci/212/4500/1279.full.pdf

Somatomedin-C mediates growth hormone negative feedback by effects on both the hypothalamus and the pituitary

The gene for the human platelet alpha 2-adrenergic receptor has been cloned with oligonucleotides corresponding to the partial amino acid sequence of the purified receptor. The identity of this gene has been confirmed by the binding of alpha 2-adrenergic ligands to the cloned receptor expressed in Xenopus laevis oocytes. The deduced amino acid sequence is most similar to the recently cloned human beta 2- and beta 1-adrenergic receptors; however, similarities to the muscarinic cholinergic receptors are also evident. Two related genes have been identified by low stringency Southern blot analysis. These genes may represent additional alpha 2-adrenergic receptor subtypes.

http://science.sciencemag.org/content/sci/238/4827/650.full.pdf

Cloning, sequencing, and expression of the gene coding for the human platelet alpha 2-adrenergic receptor

The alpha 2 and beta 2 adrenergic receptors, both of which are activated by epinephrine, but which can be differentiated by selective drugs, have opposite effects (inhibitory and stimulatory) on the adenylyl cyclase system. The two receptors are homologous with each other, rhodopsin, and other receptors coupled to guanine nucleotide regulatory proteins and they contain seven hydrophobic domains, which may represent transmembrane spanning segments. The function of specific structural domains of these receptors was determined after construction and expression of a series of chimeric alpha 2-,beta 2-adrenergic receptor genes. The specificity for coupling to the stimulatory guanine nucleotide regulatory protein lies within a region extending from the amino terminus of the fifth hydrophobic domain to the carboxyl terminus of the sixth. Major determinants of alpha 2- and beta 2-adrenergic receptor agonist and antagonist ligand binding specificity are contained within the seventh membrane spanning domain. Chimeric receptors should prove useful for elucidating the structural basis of receptor function.

https://science.sciencemag.org/content/sci/240/4857/1310.full.pdf

Chimeric alpha 2-,beta 2-adrenergic receptors: delineation of domains involved in effector coupling and ligand binding specificity

The chemokines CXCL9/Mig, CXCL10/IP-10, and CXCL11/I-TAC regulate lymphocyte chemotaxis, mediate vascular pericyte proliferation, and act as angiostatic agents, thus inhibiting tumor growth. These multiple activities are apparently mediated by a unique G protein-coupled receptor, termed CXCR3. The chemokine CXCL4/PF4 shares several activities with CXCL9, CXCL10, and CXCL11, including a powerful angiostatic effect, but its specific receptor is still unknown. Here, we describe a distinct, previously unrecognized receptor named CXCR3-B, derived from an alternative splicing of the CXCR3 gene that mediates the angiostatic activity of CXCR3 ligands and also acts as functional receptor for CXCL4. Human microvascular endothelial cell line-1 (HMEC-1), transfected with either the known CXCR3 (renamed CXCR3-A) or CXCR3-B, bound CXCL9, CXCL10, and CXCL11, whereas CXCL4 showed high affinity only for CXCR3-B. Overexpression of CXCR3-A induced an increase of survival, whereas overexpression of CXCR3-B dramatically reduced DNA synthesis and up-regulated apoptotic HMEC-1 death through activation of distinct signal transduction pathways. Remarkably, primary cultures of human microvascular endothelial cells, whose growth is inhibited by CXCL9, CXCL10, CXCL11, and CXCL4, expressed CXCR3-B, but not CXCR3-A. Finally, monoclonal antibodies raised to selectively recognize CXCR3-B reacted with endothelial cells from neoplastic tissues, providing evidence that CXCR3-B is also expressed in vivo and may account for the angiostatic effects of CXC chemokines.

https://rupress.org/jem/article-pdf/197/11/1537/1143482/jem197111537.pdf

An alternatively spliced variant of CXCR3 mediates the inhibition of endothelial cell growth induced by IP-10, Mig, and I-TAC, and acts as functional receptor for platelet factor 4.

Effects of sildenafil on the relaxation of human corpus cavernosum tissue in vitro and on the activities of cyclic nucleotide phosphodiesterase isozymes

Enzyme changes in neonatal skeletal muscle: effect of thyroid deficiency

The effects of thyroid deficiency (Td) and of chemical sympathectomy (Sx) were studied on marker enzymes of energy metabolism in cardiac muscle of neonatal and of adult rats. Td prevented the normal development of neonatal body weight, relative heart mass, and cardiac levels of cytochrome c (-22%), citrate synthase (-27%), phosphofructokinase (-20%) and Mg2+- and Ca2+-ATPase activity of purified myofibrils (-33%, -44%). Exogenous thyroxin replacement restored those parameters studied to normal with the exception that it persistently elevated citrate synthase activity significantly above normal control levels. Responses similar to those of Td neonates occurred when adult rats were similarly treated. Sx produced no consistent effects on respiratory and glycogenolytic marker enzymes, but caused a 20% reduction in Ca2+-ATPase activity of both neonatal and adult cardiac myofibrils. These findings suggest that cardiac muscle cells require thyroxin for normal growth and enzyme development. Also, Sx may impair cardiac functional capacity by altering Ca2+ activity of actomyosin ATPase.

Effects of thyroid deficiency and sympathectomy on cardiac enzymes

/pdf/estimating-the-natural-mortality-rate-of-saucer-scallops-hx8xj75a.pdf

Estimating the natural mortality rate of saucer scallops (Ylistrum balloti) on the Queensland east coast from tag-recaptures

The last major episode of cordilleran‐style tectonism in eastern Australia was the late Paleozoic‐early Mesozoic Gondwanide Orogeny. When exactly this deformation commenced and what caused this phase of orogenesis is still debated. Using previous stratigraphic and sedimentological data from pre‐orogenic to syn‐orogenic strata, integrated with new detrital zircon U‐Pb geochronology, we investigated the onset of the Gondwanide Orogeny in the northern New England Orogen (Gogango Overfolded Zone, eastern Australia). The lowermost syn‐orogenic strata display evidence of rapid base‐level change coeval with increasingly abundant and more proximal mass‐wasting deposits, which reflect a shift to static loading‐induced subsidence and the establishment of a ∼1,600‐km long foreland basin system. The syn‐orogenic strata contain abundant detritus sourced from syn‐depositional magmatism, alongside an up‐section increase in detritus derived from uplifted older rocks of the New England Orogen. Detrital zircons show maximum depositional age of ∼276 Ma from immediately above the sequence boundary, and ∼269 Ma from an overlying formation. These results confirm previous suggestions that tectonic forcing of the orogenic hinterland affected subsidence and sedimentation patterns in the easternmost part of the basin during the middle Permian, >11 Myr prior to deformation in the western part of the foreland basin. The onset of the Gondwanide Orogeny in eastern Australia, and in other sectors of the Gondwanan margin, likely resulted from a tectonic switch from crustal extension to contraction, which was driven by increased convergence rates due to a plate reorganization event following the final assembly of Pangea.

The Onset of Gondwanide Orogeny in Eastern Australia: Insight From the Provenance of Syn‐Orogenic Strata in the New England Orogen (Australia)

The gummy shark ( Mustelus antarcticus ) is endemic to Australia and is the target of commercial ﬁ sheries in southern Australia. However, the Queensland population is subjected to low levels of ﬁ shing mortality. The present study re-analysed a limited length-at-age dataset collected from central Queensland to estimate growth parameters in a Bayesian framework, with informative priors for size-at-birth and maximum size. Growth parameters were estimated using a multimodel approach. This study showed that M. antarcticus caught in Queensland exhibits slow growth compared with conspeci ﬁ cs in southern Australia, and females grow slower and larger than do males. The combined length-at-age data for males and females was best described by the von Bertalanffy growth function and the growth parameters were L ∞ = 1852 mm (total length, TL), L 0 = 261 mm TL and k = 0.044 year − 1 for males and females combined. The ‘ BayesGrowth ’ R package offers a simple method to minimise bias in the estimation of growth parameters from a limited length-at-age dataset in a Bayesian framework.

/pdf/a-re-examination-of-the-growth-of-the-gummy-shark-mustelus-30zxl2kn.pdf

P. J. Campbell

Papers

Enzyme changes in neonatal skeletal muscle: effect of thyroid deficiency

Effects of thyroid deficiency and sympathectomy on cardiac enzymes

Estimating the natural mortality rate of saucer scallops (Ylistrum balloti) on the Queensland east coast from tag-recaptures

The Onset of Gondwanide Orogeny in Eastern Australia: Insight From the Provenance of Syn‐Orogenic Strata in the New England Orogen (Australia)

A re-examination of the growth of the gummy shark (Mustelus antarcticus) from Queensland, Australia