Fetal breathing movements and lung maturation in the congenitally abnormal human fetus

Fetal breathing movements have been studied in conjunction with features of anatomical and biochemical development of the lung at birth in fetuses with congenital abnormalities affecting the respiratory system. Total absence of fetal breathing movements or abnormal fetal breathing movements were associated with lung hypoplasia and failure of normal surfactant release into saline extracts of lung fluid. Surfactant synthesis was demonstrated regardless of the presence or absence of fetal breathing movements. The study supports the hypothesis that normal fetal breathing movements are important for fetal lung development and suggests that surfactant synthesis and its release are independent. The latter process may be dependent upon fetal breathing movements while the former is not.     

The composition of intracellular granules from the metal-accumulating cells of the common garden snail (Helix aspersa).

Certain cells in the hepatopancreas of the common garden snail (Helix aspersa) contain intracellular granules that are sites of metal-ion accumulation. These granules have been extracted and investigated by u.v. and i.r. spectroscopy, atomic-absorption spectroscopy, X-ray microanalysis, thermogravimetric analysis, enzymic assay and microanalysis. The deposits contain about 18% (w/w) water, 5% (w/w) organic matter and 76% (w/w) inorganic material of which the main components are Ca2+, Mg2+ and P2O7(4)-. The possible origin of these granules is discussed, as is their role in detoxifying heavy-metal ions.     

Tumor necrosis factor induction of endothelial cell surface antigens is independent of protein kinase C activation or inactivation. Studies with phorbol myristate acetate and staurosporine.

We have investigated whether TNF-induced changes in human endothelial cell (EC) surface Ag expression are mediated by protein kinase C (PKC). This suggestion arose from the observations that PMA, a potent PKC activator, can mimic TNF by inducing expression of endothelial leukocyte adhesion molecule 1, intercellular adhesion molecule 1 (ICAM-1), and class I MHC molecules on human EC. However, in contrast to the actions of PMA, TNF neither causes membrane translocation of PKC nor induces the phosphorylation of the myristoylated alanine-rich C kinase substrate, two measures of PKC activation. Moreover, the PKC inhibitor staurosporine can block PMA-induced endothelial leukocyte adhesion molecule 1 expression at 4 h, but does not inhibit the actions of TNF. At 24 h, staurosporine itself induces intercellular adhesion molecule 1 and class I MHC, and acts additively with TNF. Twenty four hour treatment with PMA causes loss of PKC. We propose that at 24 h, staurosporine and PMA share a mechanism of action, namely diminution of PKC activity. However, 24 h treatment with TNF does not reduce the amount of PKC nor does it prevent activation of PKC by PMA. We conclude that TNF effects in EC are not mediated by PKC activation or inactivation.     

Molecular weight and amino acid composition of purified spinach beet phenolase

The purification of spinach beet phenolase has been modified to include equilibration of the crude macerate with 0.5% cetyl-trimethylammonium bromide a     

Effects of grazing on grassland soil carbon: a global review

Soils of grasslands represent a large potential reservoir for storing CO₂, but this potential likely depends on how grasslands are managed for large mammal grazing. Previous studies found both strong positive and negative grazing effects on soil organic carbon (SOC) but explanations for this variation are poorly developed. Expanding on previous reviews, we performed a multifactorial meta‐analysis of grazer effects on SOC density on 47 independent experimental contrasts from 17 studies. We explicitly tested hypotheses that grazer effects would shift from negative to positive with decreasing precipitation, increasing fineness of soil texture, transition from dominant grass species with C₃ to C₄ photosynthesis, and decreasing grazing intensity, after controlling for study duration and sampling depth. The six variables of soil texture, precipitation, grass type, grazing intensity, study duration, and sampling depth explained 85% of a large variation (±150 g m^?2 yr^?1) in grazing effects, and the best model included significant interactions between precipitation and soil texture (P = 0.002), grass type, and grazing intensity (P = 0.012), and study duration and soil sampling depth (P = 0.020). Specifically, an increase in mean annual precipitation of 600 mm resulted in a 24% decrease in grazer effect size on finer textured soils, while on sandy soils the same increase in precipitation produced a 22% increase in grazer effect on SOC. Increasing grazing intensity increased SOC by 6–7% on C₄‐dominated and C₄–C₃ mixed grasslands, but decreased SOC by an average 18% in C₃‐dominated grasslands. We discovered these patterns despite a lack of studies in natural, wildlife‐dominated ecosystems, and tropical grasslands. Our results, which suggest a future focus on why C₃ vs. C₄‐dominated grasslands differ so strongly in their response of SOC to grazing, show that grazer effects on SOC are highly context‐specific and imply that grazers in different regions might be managed differently to help mitigate greenhouse gas emissions.     

Cloning and analysis of DNA sequences from Streptomyces hygroscopicus encoding geldanamycin biosynthesis

A gene library constructed from large (20 kb) fragments of total DNA from the geldananmycin-producing strain Streptomyces hygroscopicus 3602 cloned in the plasmid vector pIJ61 were used to transform S. lividans TK24. Three transformants of about 800 tested were found to have acquired the ability to produce an antibiotic lethal to a geldanamycin-sensitive strain of Bacillus subtilis. The plasmids isolated from these transformants, pIA101, pIA102 and pIA103, each contained an insert of 15 kb. A 4.5 kb DNA fragment from the insert in pIA102 hybridised to DNA from S. hygroscopicus 3602 and to DNA encoding part of the erythromycin polyketide synthase but not to S. lividans TK24 DNA. The integration-defective phage vector C31 KC515 containing this 4.5 kb fragment was able to lysogenise S. hygroscopicus 3602 to produce lysogens defective in geldanamycin production. Loss of the prophage restored the ability to produce geldanamycin. Extracts of fermentation broth cultures of S. lividans containing pIA101, pIA102 and pIA102 and pIA103 analysed by thin-layer chromatography (TLC) contained compounds identical or very similar to purified geldanamycin, which were not present in S. lividans. These compounds showed a mass spectrum indistinguishable from geldanamycin. The evidence suggests that the clones contain DNA sequences encoding functions required for geldanamycin biosynthesis including components of the polyketide synthase.     

Rosiglitazone stimulates nitric oxide synthesis in human aortic endothelial cells via AMP-activated protein kinase

The thiazolidinedione anti-diabetic drugs increase activation of endothelial nitric-oxide (NO) synthase by phosphorylation at Ser-1177 and increase NO bioavailability, yet the molecular mechanisms that underlie this remain poorly characterized. Several protein kinases, including AMP-activated protein kinase, have been demonstrated to phosphorylate endothelial NO synthase at Ser-1177. In the current study we determined the role of AMP-activated protein kinase in rosiglitazone-stimulated NO synthesis. Stimulation of human aortic endothelial cells with rosiglitazone resulted in the time- and dose-dependent stimulation of AMP-activated protein kinase activity and NO production with concomitant phosphorylation of endothelial NO synthase at Ser-1177. Rosiglitazone stimulated an increase in the ADP/ATP ratio in endothelial cells, and LKB1 was essential for rosiglitazone-stimulated AMPK activity in HeLa cells. Infection of endothelial cells with a virus encoding a dominant negative AMP-activated protein kinase mutant abrogated rosiglitazone-stimulated Ser-1177 phosphorylation and NO production. Furthermore, the stimulation of AMP-activated protein kinase and NO synthesis by rosiglitazone was unaffected by the peroxisome proliferator-activated receptor-gamma inhibitor GW9662. These studies demonstrate that rosiglitazone is able to acutely stimulate NO synthesis in cultured endothelial cells by an AMP-activated protein kinase-dependent mechanism, likely to be mediated by LKB1.