Developmental changes in alcohol-dehydrogenase activity in rat and guinea-pig liver

1. Alcohol-dehydrogenase activity is first detectable in the rat foetus on about the eighteenth day of gestation, after which time it increases to about 25% of the adult activity at birth. Adult activity is reached at about 18 days after birth. The ethanol-oxidizing capacity of liver slices from rats correlates well with the increase of the enzyme activity in vitro. 2. In the guinea pig there is a steady linear increase from about 17 days before term to 5 days after birth. Adult activity is reached between the sixth and eighth postnatal day. 3. Some kinetic properties of liver alcohol dehydrogenase are very similar in newborn and adult rats. 4. Administration of ethanol to pregnant rats during the latter half of gestation had no effect on alcohol-dehydrogenase activity in the liver of the newborn offspring. Intraperitoneal injections of ethanol to newborn and young rats had no effect on the alcohol-dehydrogenase activity of the livers. 5. Intraperitoneal injections of hydrocortisone and triamcinolone to newborn and adult non-adrenalectomized rats had no significant effect on the increase of the alcohol-dehydrogenase activity as studied up to 4 days after the injection.     

Substantial Organic and Particulate Nitrogen and Phosphorus Export from Geomorphologically Stable African Tropical Forest Landscapes

Ecosystems - Aquatic losses of nutrients are important loss vectors in the nutrient budgets of tropical forests. Traditionally, research has focused mainly on losses of inorganic nutrient forms,...     

Growth of the metal framework in linear ruthenium and osmium carbonyls

Formation of the linear chain ruthenium and osmium carbonyls by successive linkage of mononuclear [M(CO)₄Cl₂] units and by opening trinuclear clusters [M₃(CO)₁₂] and [FeM₂(CO)₁₂] (M = Ru, Os) with chlorine gas have been studied by computational DFT methods. Energetically the formation of dinuclear [M₂(CO)₈Cl₂] from [M(CO)₄Cl₂] units is the most demanding step. The following chain growth by adding new mononuclear units proceeds more easily with nearly constant energy per step. Cluster opening by chlorine gas to obtain trinuclear [M₃(CO)₁₂Cl₂] is a facile reaction for both ruthenium and osmium clusters as well as for mixed metal clusters. Mixed metal clusters [FeOs₂(CO)₁₂] and [FeRu₂(CO)₁₂] open preferably between iron-osmium or iron-ruthenium bonds producing linear trinuclear Fe-M-M-type of compound. In the case of mixed metal Os-Ru clusters, the cleavage of Os-Ru bond is not clearly preferred. Fragmentation of the cluster to shorter units cis(Cl)-[M(CO)₄Cl₂] or [M₂(CO)₈Cl₂] with equatorial chlorides is highly favorable and competes with the cluster opening. No preferences on the bond type (Os-Ru, Os-Os, or Ru-Ru) that are broken can be found in the case of mixed metal Os-Ru clusters.     

Metabolic adaptation allows Amacr-deficient mice to remain symptom-free despite low levels of mature bile acids

Bile acids play multiple roles in the physiology of vertebrates; they facilitate lipid absorption, serve as signaling molecules to control carbohydrate and lipid metabolism, and provide a disposal route for cholesterol. Unexpectedly, the α-methylacyl-CoA racemase (Amacr) deficient mice, which are unable to complete the peroxisomal cleavage of C27-precursors to the mature C24-bile acids, are physiologically asymptomatic when maintained on a standard laboratory diet. The aim of this study was to uncover the underlying adaptive mechanism with special reference to cholesterol and bile acid metabolism that allows these mice to have a normal life span. Intestinal cholesterol absorption in Amacr −/− mice is decreased resulting in a 2-fold increase in daily cholesterol excretion. Also fecal excretion of bile acids (mainly C27-sterols) is enhanced 3-fold. However, the body cholesterol pool remains unchanged, although Amacr-deficiency accelerates hepatic sterol synthesis 5-fold. Changes in lipoprotein profiles are mainly due to decreased phospholipid transfer protein activity. Thus Amacr-deficient mice provide a unique example of metabolic regulation, which allows them to have a normal lifespan in spite of the disruption of a major metabolic pathway. This metabolic adjustment can be mainly explained by setting cholesterol and bile acid metabolism to a new balanced level in the Amacr-deficient mouse.     

30 years brings changes to the arthropod community of Kibale National Park,Uganda

World-wide declines in arthropod abundance and diversity are a major concern, particularly given their importance in ecosystem functioning. Yet, data documenting long-term trends are rare from the tropics, particularly the Afrotropics. Here we evaluate changes in the arthropod communities in Kibale National Park, Uganda across almost four decades. Systematic sweep-net sampling was conducted in two forested sections of the park that had been logged and in one old-growth forest area over 12 consecutive months in 1983/1984 and 2020/2021. This data was augmented with intermittent samples taken in 1986 and 1995. Arthropod abundance declined in all areas, but only significantly so in the moderately logged forestry compartment (41%). Permutational multivariate analysis of variance indicated that community compositions of arthropods differed between the censuses. Understanding the drivers of changes in the arthropod communities is difficult as the system is complex and dynamic. We document an increase in temperature, but no change in rainfall, increases in 11 mammal species, including a marked increase in elephant numbers, and changes in forest structure. We also report on changes in the landscape outside of the park, which includes the human population increasing by a factor of four and agricultural intensification that now includes the use of pesticides. We document that many components of the ecosystem we studied changed simultaneously, which signals that for effective conservation planning, more long-term multi-disciplinary efforts are needed.     

Structural Co-Evolution of Viruses and Cells in the Primordial World

Viruses and cells co-evolve due to the parasitic nature of viruses. Yet there are no models suggesting how the unicellular organisms and their viruses might co-evolve structurally. Here, in this study, we plunge into this unexplored field from a wide perspective and try to describe some of the intriguing ways in which viruses may have shaped the cellular life forms on the ancient Earth. At first we propose a scenario where viruses act as a driving force in the emergence of bacterial cell walls by providing favorable intermediates for the otherwise improbable steps in the cell wall generation. We also discuss the role of viruses in the evolution of cell surface components such as receptors and second membranes. Finally we focus on hypothetical proto-viruses, the selfish abusers of the RNA-world, in explaining some of the very early stages in the origin and evolution of life. Proto-viruses may be responsible for creating the first true cells in order to support their selfish needs. In this model we also suggest a logical pathway to explaining the emergence of modern viruses.     

Gap felling as a forest harvesting method in boreal forests: responses of carabid beetles (Coleoptera, Carabidae)

In order to study the ecological effects of logging combined with mechanical soil preparation, we sampled carabid beetles with pitfall trapping in nine spruce-dominated stands in central Finland in 1995–1998. Three of the stands were left intact as controls. Three 1600-m² openings per stand were logged in the winter 1995–1996 into six stands. In three of these stands, light soil preparation was applied. Logging affected the species assemblages, but soil preparation per se had no clear effects. Open-habitat species increased in abundance in the openings one year after logging, but catches of generalist species in the different treatments did not differ from each other. A forest species, Calathus micropterus , was least abundant in the prepared openings. The amounts of logging residue, exposed mineral soil and aggregated humus, as well as the abundance of red wood ants, significantly explained variation in carabid assemblages.