Localization of liver myofibroblasts and hepatic stellate cells in normal and diseased rat livers: distinct roles of (myo-)fibroblast subpopulations in hepatic tissue repair

Previous in vitro studies indicated that hepatic stellate cells (HSC) and rat liver myofibroblasts (rMF) have to be regarded as different cell populations of the myofibroblastic lineage with fibrogenic potential. Employing the discrimination features defined by these studies the localization of HSC and rMF was analyzed in diseased livers. Normal and acutely as well as chronically carbon tetrachloride-injured livers were analyzed by immunohistochemistry and by in situ hybridization. In normal livers HSC [desmin/glial fibrillary acid protein (GFAP)-positive cells] were distributed in the hepatic parenchyma, while rMF (desmin/smooth muscle alpha actin-positive, GFAP-negative cells colocalized with fibulin-2) were located in the portal field, the walls of central veins, and only occasionally in the parenchyma. Acute liver injury was characterized almost exclusively by an increase in the number of HSC, while the amount of rMF was nearly unchanged. In early stages of fibrosis, HSC and rMF were detected within the developing scars. In advanced stages of fibrosis, HSC were mainly present at the scar–parenchymal interface, while rMF accounted for the majority of the cells located within the scar. At every stage of fibrogenesis, rMF, in contrast to HSC, were only occasionally detected in the hepatic parenchyma. HSC and rMF are present in normal and diseased livers in distinct compartments and respond differentially to tissue injury. Acute liver injury is followed by an almost exclusive increase in the number of HSC, while in chronically injured livers not only HSC but also rMF are involved in scar formation. Accepted: 16 September 1999     

Identification of a biochemically unique DNA-membrane interaction involving the Escherichia coli origin of replication.

DNA-membrane complexes have been obtained from Escherichia coli by using a freeze-thaw lysis procedure that avoids lysozyme and detergents. Complexes made in this manner and containing DNA near the origin of replication are uniquely sensitive to ionic strength, Pronase, and trypsin. There is approximately one such complex per chromosomal origin. The sensitivities suggest that origin-specific binding is mediated by a protein. By using these unique characteristics to distinguish origin-specific complexes from the majority of DNA-membrane binding sites, it was found that the origin-specific binding persists after termination of chromosomal replication.     

Nesting behavior of greater eelpout (Lycodes esmarkii), identified through a predation event by spotted wolffish (Anarhichas minor)

The stomach of a spotted wolffish (Anarhichas minor) caught in Icelandic waters was found to contain ~727 greater eelpout larvae (Lycodes esmarkii). All the larvae were of similar size and at a similar state of digestion, indicating they were all consumed together. The likely explanation for this observation is that greater eelpout lay their eggs in a nest, with the larvae remaining in the nest for a short period after hatching. The larvae were then predated upon by the spotted wolffish while still in the nest. This study sheds new light on greater eelpout in Icelandic waters, with recently hatched larvae being present in March, breeding at a depth of ~200–250 m, and likely exhibiting nesting behavior, which has not previously been documented.     

Structure of the Large Subunit rDNA from a Diatom, and Comparison Between Small and Large Subunit Ribosomal RNA for Studying Stramenopile Evolution

The aim of this study was to compare the usefulness of complete small and large subunit rRNA, and a combination of both molecules, for reconstructing stramenopile evolution. To this end, phylogenies from species of which both sequences are known Acre constructed with the neighbor-joining, maximum parsimony, and maximum likelihood methods. Also the use of structural features of the rRNAs was evaluated. The large subunit rRNA from the diatom Skeletonema pseudocostatum was sequenced in order to have a more complete taxon sampling, and a group I intron was identified. Our results indicated that heterokont algae are monophyletic, with diatoms diverging first. However, as the analysis was restricted to a particular data set containing merely six taxa, the outcome has limited value for elucidating stramenopile relationships. On the other hand, this approach permits comparison of the performance of both rRNA molecules without interference from other factors, such as a different species selection for each molecule. For the taxa used, the large subunit rRNA clearly contained more phylogenetic information than the small subunit rRNA. Although this result can definitely not be generalized and depends on the phvlogeny to be studied, in some cases determining complete large subunit rRNA sequences certainly seems worthwhile.     

Serine/threonine protein phosphatases in Dictyostelium discoideum: no evidence for type I activity.

Extracts from Dictyostelium discoideum contain type 2A and 2C serine/threonine-specific protein phosphatases with properties very similar to those from mammals according to their sensitivity to okadaic acid and to their dependence for divalent cations. In contrast, no type 1 protein phosphatase is found at any time of development, neither in the cytosolic nor in the particulate fraction, using glycogen phosphorylase a, casein, histone or the non-proteinous 4-Methylumbelliferyl phosphate as substrates. Both type 2A and 2C protein phosphatase activities remain constant throughout the development cycle.     

Significant increase in natural disturbance impacts on European forests since 1950

Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long-term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground-based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m³ of disturbed timber volume per year over the 70-year study period. This value is likely a conservative estimate due to under-reporting, especially of small-scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m³/year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long-term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes.     

Sexually mature and immature yearling male European ground squirrels: a comparison of behavioral and physiological parameters

Early puberty may increase lifetime reproductive success, but may also entail diverse costs. In male European ground squirrels (Spermophilus citellus), age at sexual maturity varies among individuals. We compared sexually active and inactive yearling males under standardized conditions in outdoor enclosures. Non-reproductive yearling males hibernated significantly longer than mature males and emerged when the mating period had already started. Testosterone concentrations peaked in the precocious males during premating and mating, and were depressed in the non-reproductive individuals throughout the study period. Emergence body mass was similar in both groups, although sexually immature males were significantly heavier at the end of the active season. Additionally, non-reproductive yearlings grew faster than precocious individuals. Male–male aggression peaked during mating and the following 4 weeks. Intense aggressive interactions like chases and fights were mostly initiated by reproductive males and were directed towards mature competitors. Aggressive behavior in immature males was mainly expressed as spatial displacements. Non-agonistic interactions with females were only observed in sexually active males. Concentrations of fecal cortisol metabolites did not differ between the two male groups and were elevated in the second half of the active season. Leucocyte numbers were reduced during mating in mature males, whereas in immature animals, cell numbers did not change significantly. Our results indicate that early puberty in European ground squirrels involves lower growth rates, high intrasexual aggression, lower prehibernatory body mass, and probably worse immunological condition during mating.     

Testing generalized allometries in allocation modeling within an individual-based simulation framework

The allocation of carbohydrates from photosynthesis to various plant compartments is a key process in ecophysiology and consequently an important element in process-based ecosystem modeling. In this study, we tested generalized empirical equations in a widely applied partitioning concept based on compartment-specific biomass allometries. For an 88-year chronosequence of European beech (Fagus sylvatica L.) in Austria, we used the individual-based hybrid forest model PICUS v1.4 to compare simulations employing foliage biomass functions at different levels of generalization against runs with site-specific parameterization and observations. Sensitivities of the individual tree model were generally in line with the original stand-level partitioning concept and ecological process understanding. While stand-level leaf area increased with increasing allocation to foliage, net primary productivity showed no significant response due to saturated radiation interception in the dense chronosequence stands. Strong sensitivities were revealed at the individual tree level, where favoring allocation to the foliage compartment resulted in increasing asymmetry of competition and height–diameter relationships. Applying a generalized parameterization based on data from the full range of continental species distribution resulted in a significant overestimation of mean tree height and subsequently standing volume stock at the chronosequence. At a lower hierarchical level of generality, however, simulations with a representative regional parameterization performed satisfactorily compared to model runs using the site-specific allometry. In relation to common accuracy demands, e.g., in forest management decision support, the study suggests the rejection of a generic parameterization while corroborating the use of regional generalizations in ecosystem models.     

Comparison of Water,Oils and Emulsifiable Adjuvant Oils as Formulating Agents for <Emphasis Type="Italic">Metarhizium Anisopliae</Emphasis> for Use in Control of <Emphasis Type="Italic">Boophilus Microplus</Emphasis>

Studies were conducted to identify oil-based formulating agents (paraffinic oil, palm oil and emulsifiable adjuvant oils (EAOs)) for Metarhizium anisopliae that were superior to water with simple surfactants using a germination test and a bioassay against Boophilus microplus. Germination of conidia in all formulations, except 10% coconut EAO, produced more than 68% germination at 24 h and nearly 100% at 48 h. Coconut oil (average survival time (AST)=4.6±0.28 days) and 10% liquid paraffin EAO (AST=4.4±0.15 days) enhanced the pathogenicity of M. anisopliae to B. microplus relative to water (AST=8.4±0.42 days). M. anisopliae in 10% liquid paraffin EAO was the most effective formulation having a moderately high germination after 24 h and a low AST as well as a high AST in the control. In the second experiment, germination of conidia in 2% liquid paraffin EAO and 2% Cropspray was higher than in 2% Codacide oil at 24 h, however, all treatments reached 100% germination after 48 h. The ASTs of the EAO based M. anisopliae formulations (Average AST=6.4±0.54 days) were similar but lower that the ASTs of the controls (Average AST=9.6±0.28 days).