Particle retention in the forestomach of a browsing ruminant, the roe deerCapreolus capreolus

A combination of a flotation/sedimentation experiment and sieve analysis for the reticulorumen (RR) contents of roe deerCapreolus capreolus Linnaeus, 1758, a browsing ruminant, showed that there was no correlation between particle size and particle density. Large particles were present in both the sedimented and the buoyant fraction, which is in accord with the reported absence of stratification of RR contents in browsing ruminants. Comparative sieve analysis of roe deer RR and caecal/rectal material demonstrated that there must be some selective particle retention in the browsing ruminant as well, as a certain fraction of large particles in RR contents does not occur in the caecal/rectal material. These results lead to the explanatory dilemma that, while selective particle retention is observed, it cannot be due to the mechanisms known to work in grazing ruminants.     

Active site characteristics of CYP4B1 probed with aromatic ligands.

The active site topography of rabbit CYP4B1 has been studied relative to CYP2B1 and CYP102 using a variety of aromatic probe substrates. Oxidation of the prochiral substrate cumene by CYP4B1, but not CYP2B1 or CYP102, resulted in the formation of the thermodynamically disfavored omega-hydroxy metabolite, 2-phenyl-1-propanol, with product stereoselectivity for the (S)-enantiomer. Reaction of CYP4B1, CYP2B1, and CYP102 with phenyldiazene produced spectroscopically observable sigma-complexes for each enzyme. Subsequent oxidation of the CYP2B1 and CYP102 complexes followed by LC/ESI--MS analysis yielded heme pyrrole migration patterns similar to those in previous literature reports. Upon identical treatment, no migration products were detected for CYP4B1. Intramolecular deuterium isotope effects for the benzylic hydroxylation of o-xylene-alpha-(2)H(3), p-xylene-alpha-(2)H(3), 2-(2)H(3),6-dimethylnaphthalene, and 4-(2)H(3),4'-dimethylbiphenyl were determined for CYP4B1 and CYP2B1 to further map their active site dimensions. These probes permit assessment of the ease of equilibration, within P450 active sites, of oxidizable methyl groups located between 3 and 10 A apart [Iyer et al. (1997) Biochemistry 36, 7136--7143]. Isotope effects for the CYP4B1-mediated benzylic hydroxylation of o- and p-xylenes were fully expressed (k(H)/k(D) = 9.7 and 6.8, respectively), whereas deuterium isotope effects for the naphthyl and biphenyl derivatives were both substantially masked (k(H)/k(D) approximately equal to 1). In contrast, significant suppression of the deuterium isotope effects for CYP2B1 occurred only with the biphenyl substrate. Therefore, rapid equilibration between two methyl groups more than 6 A apart is impeded within the active site of CYP4B1, whereas for CYP2B1, equilibration is facile for methyl groups distanced by more than 8 A. Collectively, all data are consistent with the conclusion that the active site of CYP4B1 is considerably restricted relative to CYP2B1.     

Proliferative diabetic retinopathy is associated with a low level of the natural ocular anti-angiogenic agent pigment epithelium-derived factor (PEDF) in aqueous humor. a pilot study.

Retinopathy is the most common microvascular diabetes complication and represents a major threat to the eyesight. The aim of this study was to address the role of pro- and anti-angiogenic molecules in diabetic retinopathy in the aqueous humor of the eye. Aqueous humor was collected at cataract surgery from 19 diabetic patients and from 13 age- and sex-matched normoglycemic controls. Levels of pro-angiogenic vascular endothelial growth factor (VEGF) and angiogenic inhibitor pigment epithelium-derived factor (PEDF) were determined. Angiogenic activity of the aqueous humor was quantified by measuring its effect on the migration of capillary endothelial cells. In the aqueous fluid, VEGF levels were increased in diabetics (mean values: 501 vs. 367 pg/ml; p = 0.05), compared to controls. PEDF was found to be decreased in diabetics (mean values: 2080 vs. 5780 ng/ml; p = 0.04) compared to controls. In seven diabetic patients with proliferative retinopathy, the most profound finding was a significant decrease of the PEDF level (mean value: 237 ng/ml), whereas VEGF levels were comparable to diabetic patients without proliferation (mean value: 3153; p = 0.003). Angiogenic activity in samples of patients from the control group was generally inhibitory due to PEDF, and inhibition was blocked by neutralizing antibodies to PEDF. Likewise, in diabetics without proliferation, angiogenic activity was also blocked by antibodies to PEDF. We will demonstrate here that the level of the natural ocular anti-angiogenic agent PEDF is inversely associated with proliferative retinopathy. PEDF is an important negative regulator of angiogenic activity of aqueous humor. Our data may have implications for the development of novel regimens for diabetic retinopathy.     

Are human beings part of the rest of nature?

Unified explanations seek to situate the traits of human beings in a causal framework that also explains the trait values found in nonhuman species. Disunified explanations claim that the traits of human beings are due to causal processes not at work in the rest of nature. This paper outlines a methodology for testing hypotheses of these two types. Implications are drawn concerning evolutionary psychology, adaptationism, and anti-adaptationism. This revised version was published online in July 2006 with corrections to the Cover Date.     

Do female degus communally nest and nurse their pups?

We examined the nesting and nursing behavior of females of the caviomorph rodent Octodon degus. We recorded the behavior of two, three-female groups of lactating degus kept in captivity and compared it with that of singly housed lactating females. Grouped females spontaneously nested communally. Five of six lactating females had non-offspring pups hanging from their teats, which suggests that some non-offspring nursing took place. Non-mothers increased their maternal behavior after the delivery of their own pups. Although time allocated to parental care by each communally nesting dam did not differ from that of solitary lactating females, young of communal litters spent less time alone and enjoyed more time cared for by a lactating female than young of single dams. Electronic Publication     

Regional analysis of litter quality in the central grassland region of North America

Abstract. The central grassland region of North America is characterized by large gradients of temperature and precipitation. These climatic variables are important determinants of the distribution of plant species, and strongly influence plant morphology and tissue chemistry. We analysed regional patterns of plant litter quality as they vary with climate in grassland ecosystems throughout central North America including tall‐grass prairie, mixed grass prairie, shortgrass steppe, and hot desert grasslands. An extensive database from the International Biological Program and the Long‐Term Ecological Research Program allowed us to isolate the effects of climate from those of plant functional types on litter quality. Our analysis of grass species confirms a previously recognized positive correlation between C/N ratios and precipitation. Precipitation exhibited a similar positive relationship with lignin/N and percent lignin. Although there was no significant correlation between temperature and C/N, there was a significant positive relationship between temperature and both percent lignin and lignin/N. Among functional types, C₃ grasses had a slightly lower C/N ratio than C₄ grasses. Tall grass species exhibited higher C/N, lignin/N, and percent lignin than short grass species. This understanding of the regional patterns of litter quality and the factors controlling them provides us with a greater knowledge of the effect that global change and the accompanying feedbacks may have on ecosystem processes.     

Distribution of serotonergic and dopaminergic nerve fibers in the salivary gland complex of the cockroach Periplaneta americana

Background  

Iron deficiency (ID) results in ventricular hypertrophy, believed to involve sympathetic stimulation. We hypothesized that with ID 1) intravenous norepinephrine would alter heart rate (HR) and contractility, 2) abdominal aorta would be larger and more distensible, and 3) the beta-blocker propanolol would reduce hypertrophy.     

In vitro and in vivo inhibition of LPS-induced tumor necrosis factor-alpha production by dimeric gallotannin analogues.

Designed dimeric gallotannin analogues featuring two tetragalloylglucopyranose cores connected by various hydrocarbon linkers inhibit tumor necrosis factor-alpha secretion from lipopolysaccharide-stimulated human peripheral blood mononuclear cells by up to 53% (5-24 microM concentration range) compared to control. Comparable suppression of tumor necrosis factor-alpha levels (approximately 50% vs control) was observed in the plasma of rats co-treated with lipopolysaccharide and specific tannin analogues selected for their lack of interleukin 1-beta stimulating activity.     

The brefeldin A resistance protein Bfr1p is a component of polyribosome-associated mRNP complexes in yeast

The yeast gene BFR1 was originally isolated from a genetic screen for high-copy suppressors of brefeldin A-induced lethality in Saccharomyces cerevisiae. While this result suggested a possible role for the encoded protein, Bfr1p, in the secretory pathway, subsequent data have not fully supported this conclusion. Alternatively, Bfr1p has also been found by yeast two-hybrid analysis to interact with Bbp1p, a component of the spindle pole body. Finally, we have reported that Bfr1p associates with cytoplasmic mRNP complexes containing Scp160p, raising the possibility that Bfr1p may function in mRNA metabolism. Here, we have explored this possibility further. We report that Bfr1p associates with yeast polyribosomes and mRNP complexes even in the absence of Scp160p, and that its interaction with Scp160p-containing mRNP complexes is RNA-dependent. Furthermore, we have determined by fluorescence microscopy and subcellular fractionation that Bfr1p and Scp160p demonstrate similar cytoplasmic localization with enrichment around the nuclear envelope/endoplasmic reticulum. Finally, we report that loss of Bfr1p disrupts the interaction of Scp160p with polyribosomes, thereby demonstrating that the relationship between these two proteins is functional as well as physical. Considered together, these data raise the intriguing possibility that Bfr1p may provide a link between mRNA metabolism, the chromosomal segregation machinery and perhaps secretion in yeast.