Room to roam for African lions Panthera leo: a review of the key drivers of lion habitat use and implications for conservation

1. Globally, large terrestrial carnivores (Carnivora) have suffered precipitous declines in population and range. Today, they must persist in increasingly isolated natural habitat patches within a human-dominated matrix. Effective conservation aimed at supporting carnivores in such landscapes requires species-specific understanding of habitat requirements.
2. We present results from a review of the published literature to assess the current state of knowledge regarding habitat preferences of the African lion Panthera leo, with the aim of identifying common drivers of habitat use across contexts.
3. Using the Web of Science, we identified 154 usable articles and extracted information relating to study topic, location, habitats described, land-use type, and any documented habitat preferences.
4. Only 31 studies documented evidence of habitat use, and collectively, they suggested that preferences for specific habitat types were varied and context-specific. The importance of prey abundance and proximity to water was highlighted in multiple studies. Anthropogenic factors interfered with expected patterns of habitat use. There was evident bias in study locations: 83% of the habitat-use studies were based in only three countries, and 70% were focussed on protected or managed areas.
5. Our synthesis suggests that lions demonstrate behavioural plasticity in habitat use in response to anthropogenic pressures. To understand the limits of this plasticity and to manage Africa’s changing landscapes effectively for roaming lions, future research should be focussed on analysis of habitat use outside protected areas, taking into account gradients of distance to water, prey abundance, and anthropogenic risk.

     

Targeting of the Enhanced Green Fluorescent Protein Reporter to Adrenergic Cells in Mice

Adrenaline and noradrenaline are important neurotransmitter hormones that mediate physiological stress responses in adult mammals, and are essential for cardiovascular function during a critical period of embryonic/fetal development. In this study, we describe a novel mouse model system for identifying and characterizing adrenergic cells. Specifically, we generated a reporter mouse strain in which a nuclear-localized enhanced green fluorescent protein gene (nEGFP) was inserted into exon 1 of the gene encoding Phenylethanolamine n-methyltransferase (Pnmt), the enzyme responsible for production of adrenaline from noradrenaline. Our analysis demonstrates that this knock-in mutation effectively marks adrenergic cells in embryonic and adult mice. We see expression of nEGFP in Pnmt-expressing cells of the adrenal medulla in adult animals. We also note that nEGFP expression recapitulates the restricted expression of Pnmt in the embryonic heart. Finally, we show that nEGFP and Pnmt expressions are each induced in parallel during the in vitro differentiation of pluripotent mouse embryonic stem cells into beating cardiomyocytes. Thus, this new mouse genetic model should be useful for the identification and functional characterization of adrenergic cells in vitro and in vivo.     

Comparison between filament lamps and compact fluorescent lamps

“Produktlinienanalyse” (PLA) and life cycle assessment are analytical approaches which are used as instruments to survey the life cycle of a product, but whose main purpose can be viewed as being the optimization of this life cycle. The lesser known instrument of PLA includes an appraisal of product utility, and assesses the life cycle not only according to environmental, but also according to economic and social impacts. Moreover, PLA involves the agents relevance to the life cycle. This case study, a comparison between filament lamps and compact fluorescent lamps, shows that the purely environmental perspective is insufficient and omits a series of relevant criteria. It illustrates that additional social and economic parameters, and the examination of the utility of a product, have a great impact upon this comparison. The method of product system improvement with agent cooperation is put forward as a technique for the transposition of the results into concrete action. This study was financed from own funds of the Öko-Institut e.V., Freiburg.     

Inhibition of cellular autophagy in kidney tubular cells stimulated to grow by unilateral nephrectomy

Cytoplasmic growth (hypertrophy) presupposes a positive metabolic balance brought about by increased anabolic and/or decreased catabolic processes. Degradation of cytoplasmic components takes place in autophagic vacuoles (AVs) whose volume fraction may be taken as a measure of the relative rate of degradation of cytoplasmic components. Male adult Sprague-Dawley rats (n = 80) were unilaterally nephrectomized (n = 40) or sham-operated (n = 40) and were killed 3.5-57.5 h p.o. The volume density of AVs in parenchymal cells of renal cortical convoluted tubules was determined morphometrically by systematic evaluation of large test fields in the electron microscope. During compensatory renal growth, the volume densities of autophagic vacuoles were reduced at day 0 (3.5-8 h p.o.), day 1 (20.5-33.5 h p.o.) and day 2 (44.5-57.5 h p.o.) by 49% (p less than 0.01), 43% (p less than 0.05), and 19% (n.s.), respectively, when compared with sham-operated controls. No decrease, and even an increase, in the AV-volume fraction was found in liver parenchymal cells of the unilaterally nephrectomized animals. This indicates that inhibition of autophagy is not a general response after unilateral nephrectomy, but is confined to the growing kidney, where it may represent a significant factor in the increase of cytoplasmic mass.     

Structure of mouse DNA (cytosine-5-)-methyltransferase

DNA (cytosine-5-)-methyltransferase was purified as a single polypeptide (190 kDa by SDS-PAGE) from mouse P815 mastocytoma cells. This enzyme transfers methyl groups to unmethylated as well as to hemimethylated DNA sites with a strong preference for the hemimethylated substrate. A structural analysis of the isolated enzyme by electron microscopical techniques was undertaken. On the basis of the results obtained, we propose a model for the enzyme structure. This model describes the enzyme as a hemi-elliptical globular structure with dimensions of 5.4-6.7 nm for the height h and 10.3-10.8 nm for the diameter d, respectively; this globular structure bears a small appendix at the flat side. A molecular mass of 235-250 kDa is calculated from the measured dimensions. Limited trypsin digestion of the enzyme led to a 160-kDa fragment which preserved the gross morphology of the original material. The possible structure function relationships are discussed.     

A morphometric study on growth of bile canaliculi after partial hepatectomy

19-33 h after partial hepatectomy there is a time-dependent increase of the bile canalicular luminal volume, of the total length of bile canaliculi, and of their non-microvillous, smooth surface, when measured per unit volume of lobular parenchyma. On average the luminal volume fraction is increased by a factor of 2.8, the length per volume by a factor of 1.4, and the density of smooth surface by a factor of 2.0, when compared with sham-operated controls. On the other hand, the volume and surface density of bile canalicular microvilli are only slightly increased after partial hepatectomy. These findings are interpreted as indicating disproportional growth of bile canaliculi which is due predominantly to the formation of new, at first non-microvillous, membrane.