Late pleistocene paleoclimates of the South Pacific based on statistical analysis of planktonic foraminifers

Statistical analysis applied to foraminiferal data from 78 South Pacific core tops enables the derivation of a transfer function that relates sea surface temperature to foraminiferal assemblages. Application of this transfer function to eight cores from the southern part of the East Pacific Rise yields estimates of the sea surface temperatures of the last glacial maximum, as well as the paleotemperature record of the past 150,000 years. Comparison of the last glacial temperature estimates with the recent sea surface temperature shows that the greatest change between glacial and present conditions (about 5°C) occurs in a climatically sensitive area near 50°S. Stratigraphic correlation of two cores from this area suggests that the last glacial started in this area with rapid cooling, and that the climate stayed generally cold until the end of the glacial. Similar general shape of the climatic record is found in the high latitudes of the North Atlantic as well as in the ice sheets of Greenland and Antarctica. In contrast to the similarity in the shape of these high-latitude records, they differ distinctly from the foraminiferal oxygen isotope record of several deep-sea cores which indicates a general gradual increase of ice volume from the beginning of the last glacial to the maximum glaciation which occurred about 18,000 years B.P.In the study area the rate of sediment accumulation during the last glacial is about two to three times less than in the last interglacial. There is no indication of increased carbonate solution during the glacial, and it is suggested that the change in the accumulation rate results from a reduction in the supply of calcareous shells to the sediment. It seems that with cooling, the environment becomes less favorable to organisms producing calcium carbonate tests, and therefore carbonate production decreases during the glacial.     

Electron spin resonance and photoreaction of Mn(II) in lettuce chloroplasts.

Electron spin resonance (esr) of lettuce chloroplasts yields three types of signals: (i) a broad (~900 G) signal around g = 2.22 (apparently due to Cu²⁺ complexes); (ii) an Mn²⁺ spectrum around g = 2.003 consisting of six hyperfine lines (A = 94.5 G) of ~30 G width; and (iii) a sharp signal at g = 2.00 due to photosignals I and II. The present work is concerned with the Mn²⁺ signal and its relation to the photosynthetic process. Intensity measurements were performed by comparing the intensities of the Mn²⁺ signals of two identical chloroplast preparations, one of which was slightly acidified. The integrated intensity of the signal in the normal preparation was approximately one-fourth of that in the acidified sample, suggesting that only the?$\text{1}\text{2}\text{?}\text{1}\text{2}$ fine structure band is observed in untreated chloroplasts. This indicates that the manganese in the chloroplasts is bound in an asymmetric environment, apparently in protein complexes. The Mn²⁺ signal is light sensitive, decreasing on illumination and reappearing in the dark. Typical values for the half-lives of the light and dark processes in normal chloroplasts are 0.25 and 2.1s, respectively. The effect is interpreted in terms of the photooxidation of Mn²⁺ to higher oxidation states which are invisible to esr spectroscopy. In order to determine whether this process is related to photosynthesis the effect of certain reagents and treatments that are known to affect the photosynthetic system was studied. It was found that the oxygen evolution inhibitors 3-(3,4 dichlorophenyl)-1,1-dimethylurea (DCMU) and carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP) as well as the electron donors, phenylenediamine and sodium ascorbate, reduce or completely eliminate the light effect on the Mn²⁺ signal. Heat treatment and Tris washing caused deceleration of both the light and dark reactions. These effects indicate that the photooxidation of the Mn²⁺ is related to the photosynthetic cycle, the most probable site being the water splitting apparatus of photosystem II.     

Molecular cloning of osteoma-inducing replication-competent murine leukemia viruses from the RFB osteoma virus stock.

We report the molecular cloning of two replication-competent osteoma-inducing murine leukemia viruses from the RFB osteoma virus stock (M. P. Finkel, C. A. Reilly, Jr., B. O. Biskis, and I. L. Greco, p. 353-366, in C. H. G. Price and F. G. M. Ross, ed., Bone--Certain Aspects of Neoplasia, 1973). Like the original RFB osteoma virus stock, viruses derived from the molecular RFB clones induced multiple osteomas in mice of the CBA/Ca strain. The cloned RFB viruses were indistinguishable by restriction enzyme analysis and by nucleotide sequence analysis of their long-terminal-repeat regions and showed close relatedness to the Akv murine leukemia virus.     

Feeding and trapping fish withPiper auritum

The “natives” at Rio Indio, on the central Caribbean slope of Panama, trap the river fishBrycon chagrensis using leaves ofPiper auritum as bait in feeders. The people use this technique because the fish tastes like the leaf after it has fed regularly on the leaf. This technique has potential use in aquaculture. The plant could also be cultivated for marketing as a food-flavoring condiment and fish food.     

Rat hypothalamic extract inhibits vasopressin-stimulated Na+-K+-ATPase activity in the rat renal medulla

Arginine vasopressin stimulates Na⁺-K⁺-ATPase activity located in the rat thick ascending limb of s'Henle loop. Mammalian hypothalamus appears to produce a factor capable of inhibiting Na⁺-K⁺-ATPase activity in a variety of tissues. The effect of a purified rat hypothalamic extract with and without AVP on rat renal Na⁺-K⁺-ATPase activity was evaluated by a cytochemical technique. The hypothalamic extract alone failed to affect basal Na⁺-K⁺-ATPase activity throughout renal segments after 10 min exposure. Na⁺-K⁺-ATPase activity stimulated by AVP (1–10 fmol l^?1) for 10 min was inhibited by rat hypothalamic extract over the concentration range 10^?7–10^?3 U ml^?1 in a dose-dependent manner. Complete inhibition of AVP-stimulated Na⁺-K⁺-ATPase activity occurred at a hypothalamic extract concentration of 10^?3 U ml^?1. Only Na⁺-K⁺-ATPase activity located in the renal medullary thick ascending limb was influenced by the rat hypothalamic extract.     

Loss of Key Riparian Plant Species Impacts Stream Ecosystem Functioning

Ecosystems - Leaf litter of alder (Alnus glutinosa) is a key resource to detrital stream food webs. Due to its high quality and palatability, it is readily colonised by microorganisms and consumed...     

Automated creation and tuning of personalised muscle paths for OpenSim musculoskeletal models of the knee joint

Biomechanics and Modeling in Mechanobiology - Computational modelling is an invaluable tool for investigating features of human locomotion and motor control which cannot be measured except through...     

Molecular underpinnings of the early brain developmental response to differential feeding in the honey bee Apis mellifera

Brain differential morphogenesis in females is one of the major phenotypic manifestations of caste development in honey bees. Brain diphenism appears at the fourth larval phase as a result of the differential feeding regime developing females are submitted during early phases of larval development. Here, we used a forward genetics approach to test the early brain molecular response to differential feeding leading to the brain diphenism observed at later developmental phases. Using RNA sequencing analysis, we identified 53 differentially expressed genes (DEGs) between the brains of queens and workers at the third larval phase. Since miRNAs have been suggested to play a role in caste differentiation after horizontal and vertical transmission, we tested their potential participation in regulating the DEGs. The miRNA-mRNA interaction network, including the DEGs and the royal- and worker-jelly enriched miRNA populations, revealed a subset of miRNAs potentially involved in regulating the expression of DEGs. The interaction of miR-34, miR-210, and miR-317 with Takeout, Neurotrophin-1, Forked, and Masquerade genes was experimentally confirmed using a luciferase reporter system. Taken together, our results reconstruct the regulatory network that governs the development of the early brain diphenism in honey bees.     

Exercise training provides cardioprotection via a reduction in reactive oxygen species in rats submitted to myocardial infarction induced by isoproterenol

Exercise training has demonstrated cardioprotection effects. However, the exact mechanism behind this effect is not is clear. The present study evaluated the effects of 12 weeks of previous treadmill training on the levels of oxidative damage, antioxidant enzyme activity and injury in the myocardium of rats submitted to infarction induced by isoproterenol (ISO). Isoproterenol treatment (80 mg/kg given over 2 days in two equal doses) caused arrhythmias and 60% mortality within 24 h of the last injection in the control group (C + ISO) group when compared with the saline control group (saline). Creatine Kinase ? MB levels were markedly increased in hearts from ISO-treated animals in the C + ISO group. Twelve weeks of treadmill training reduced superoxide production, lipid peroxidation levels and protein carbonylation in these animals, as well as increasing the activities and expressions of SOD and CAT. Previous training also reduced CK-MB levels and numbers of deaths by 40%, preventing the deleterious effects of ISO. Based on the data obtained in this study, it is suggested that 12-week treadmill training increases antioxidant enzymes, decreases oxidative damage and reduces the degree of infarction induced by ISO in the hearts of male rats.