The NAD-dependent alcohol dehydrogenase (ADH) of hansenula polymorpha cbs 4732 – an electrophoretic study (II)

Using gradient polyacrylamide gel electrophoresis (gradient between 10–20%) we were able to show up to six clearly distinguishable ADH-bands in Hansenula polymorpha CBS 4732. In contrast to commercial ADH from Saccharomyces cerevisiae the ADH-forms of Hansenula polymorpha CBS 4732 have a much broader substrate specificity. Furthermore, the occurence of secondary alcohol dehydrogenases and of an aromatic alcohol dehydrogenase could be demonstrated.     

Serotonin transporter protein in pulmonary hypertensive rats treated with atorvastatin

HMG-CoA-reductase inhibitors (statins) influence lipid metabolism and have pleiotropic effects. Several statins reduce various forms of pulmonary hypertension (PH) in animal models. The relationship between atorvastatin and expression of serotonin transporter protein (5-HTT) remains unknown. This study focused on the effects of atorvastatin on the course of monocrotaline (MCT)-induced PH and its relation to 5-HTT expression. Male Sprague-Dawley rats were challenged with MCT with or without subsequent daily oral treatment with 0.1, 1, and 10 mg/kg of atorvastatin for 28 days. Over the 4-wk course, the progression of PH was followed by transthoracic echocardiography [pulmonary artery pressure was assessed by pulmonary artery flow acceleration time (PAAT), an estimate reciprocal to pulmonary artery pressure], and, at the end of the 4-wk course, invasive right ventricular pressure, right ventricular weight, quantitative morphology, and 5-HTT expression were measured. MCT caused significant PH as early as 7 days after injection. Atorvastatin treatment increased PAAT and reduced right ventricular pressure, right ventricular hypertrophy, and vascular remodeling over the 4-wk course. MCT challenge was associated with increased pulmonary vascular 5-HTT expression, and atorvastatin treatment reduced the 5-HTT expression. MCT-induced PH over the course of 4 wk can be easily followed by transthoracic echocardiography, and atorvastatin is effective in reducing the PH. Atorvastatin's effects are associated with a decrease of 5-HTT expression.     

Interaction of interleukin-6 and the BMP pathway in pulmonary smooth muscle

The majority of familial pulmonary arterial hypertension (PAH) cases are caused by mutations in the type 2 bone morphogenetic protein receptor (BMPR2). However, less than one-half of BMPR2 mutation carriers develop PAH, suggesting that the most important function of BMPR2 mutation is to cause susceptibility to a "second hit." There is substantial evidence from the literature implicating dysregulated inflammation, in particular the cytokine IL-6, in the development of PAH. We thus hypothesized that the BMP pathway regulates IL-6 in pulmonary tissues and conversely that IL-6 regulates the BMP pathway. We tested this in vivo using transgenic mice expressing an inducible dominant negative BMPR2 in smooth muscle, using mice injected with an IL-6-expressing virus, and in vitro using small interfering RNA (siRNA) to BMPR2 in human pulmonary artery smooth muscle cells (PA SMC). Consistent with our hypothesis, we found upregulation of IL-6 in both the transgenic mice and in cultured PA SMC with siRNA to BMPR2; this could be abolished with p38(MAPK) inhibitors. We also found that IL-6 in vivo caused a twofold increase in expression of the BMP signaling target Id1 and caused increased BMP activity in a luciferase-reporter assay in PA SMC. Thus we have shown both in vitro and in vivo a complete negative feedback loop between IL-6 and BMP, suggesting that an important consequence of BMPR2 mutations may be poor regulation of cytokines and thus vulnerability to an inflammatory second hit.     

Explaining the scaling of transport costs: the role of stride frequency and stride length

The mechanisms which enable large animals to transport a unit of body mass through a unit distance at a lower metabolic cost than smaller animals have been the subject of numerous studies. Recent investigations have concluded that stride frequency is a main determinant. We examine the role of both stride frequency and stride length in determining the scaling of the cost of transport.
Slopes for regressions between stride frequency and speed and stride length and speed were determined in four species of rodents. These data were pooled with literature values for the slopes of stride frequency, stride length and cost of locomotion (all vs. speed) for a total of 17 species ranging in size from 30 g to 250 kg. Interspecific equations were calculated for each of these slopes versus body mass, and residuals from these allometric lines were calculated. Residuals were compared to see if variation in the rate of cost increase at a given size is related to variation in the rates of stride frequency and/or stride length increase.
The residual analysis revealed that the variation in transport cost is explicable only in terms of the interaction of stride frequency and stride length slopes. The product of the scaling exponents for stride frequency slope and stride length slope is not significantly different from the scaling exponent for the cost of transport. A model seeking to explain the scaling of the cost of transport must therefore consider the influence of both stride length and stride frequency.
We propose that absolutely longer limbs allow large animals to minimize the rate of increase of stride frequency and stride length with speed, and that this allows utilization of muscles with lower intrinsic rates of contraction, which in turn results in a lower mass-specific cost of transport.     

Biodiversity effects on ecosystem functioning change along environmental stress gradients

Positive relationship between biodiversity and ecosystem functioning has been observed in many studies, but how this relationship is affected by environmental stress is largely unknown. To explore this influence, we measured the biomass of microalgae grown in microcosms along two stress gradients, heat and salinity, and compared our results with 13 published case studies that measured biodiversity–ecosystem functioning relationships under varying environmental conditions. We found that positive effects of biodiversity on ecosystem functioning decreased with increasing stress intensity in absolute terms. However, in relative terms, increasing stress had a stronger negative effect on low‐diversity communities. This shows that more diverse biotic communities are functionally less susceptible to environmental stress, emphasises the need to maintain high levels of biodiversity as an insurance against impacts of changing environmental conditions and sets the stage for exploring the mechanisms underlying biodiversity effects in stressed ecosystems.     

Endotoxin priming of thromboxane-related vasoconstrictor responses in perfused rabbit lungs

Steudel, Wolfgang, Hans-Joachim Krämer, DanielaDegner, Simone Rosseau, Hartwig Schütte, Dieter Walmrath, andWerner Seeger. Endotoxin priming of thromboxane-relatedvasoconstrictor responses in perfused rabbit lungs. J. Appl. Physiol. 83(1): 18-24, 1997.In priorstudies of perfused lungs, endotoxin priming markedly enhancedthromboxane (Tx) generation and Tx-mediated vasoconstriction inresponse to secondarily applied bacterial exotoxins. Thepresent study addressed this aspect in more detail by employingprecursor and intermediates of prostanoid synthesis and performingfunctional testing of vasoreactivity and measurement of productformation. Rabbit lungs were buffer perfused in theabsence or presence of 10 ng/ml endotoxin. Repetitive intravascularbolus applications of free arachidonic acid provoked constant pulmonaryarterial pressor responses and constant release reactions ofTxA₂ and prostaglandin (PG)I₂ in nonprimed lungs. Within60-90 min of endotoxin recirculation, which provoked progressiveliberation of tumor necrosis factor- but did not effect anyhemodynamic changes by itself, both pressor responses and prostanoidrelease markedly increased, and both events were fully blocked bycyclooxygenase (Cyclo) inhibition with acetylsalicylic acid(ASA). The unstable intermediatePGG₂ provoked moderate pressorresponses, again enhanced by preceding endotoxin priming and fullysuppressed by ASA. Vasoconstriction also occurred in response to thedirect Cyclo product PGH₂, again amplified after endotoxin pretreatment, together with markedly enhancedliberation of TxA₂ andPGI₂. In the presenceof ASA, the priming-related increase in pressor responses and theprostanoid formation were blocked, but baseline vasoconstrictorresponses corresponding to those in nonprimed lungs were maintained.Pressor responses to the stable Tx analog U-46619 were notsignificantly increased by endotoxin pretreatment, but some generationof TxA₂ andPGI₂ was also noted under theseconditions. We conclude that endotoxin priming exerts profound effectson the lung vascular prostanoid metabolism, increasing the readiness toreact with Tx-mediated vasoconstrictor responses to various stimuli,suggesting that enhanced Cyclo activity is an important underlyingevent.

     

Effect of the autoregulator from Streptomyces griseus JA 5142 on surface cultures of blocked mutant ZIMET 43682

Zero time addition of the autoregulator (L-factor) from S. griseus (Lkm+Amy+) to surface cultures of its bald mutant ZIMET 43 682 (Amy-Lkm-) restored the capacity to form both anthracycline-type antibiotic leukaemomycin and aerial mycelium. The pertinent mycelia displayed the same growth rate and cellular levels of nucleic acids as the asporogeneous phenotype but the composition of fatty acids and phospholipids as well as the ratio of cytochromes b and c were altered. These differences indicate alterations in the cellular architecture of substrate and aerial hyphae. The results suggest that the autoregulator triggers the onset of a complex programme of differentiation at a very early stage.