Further evidence that there is more than one adrenal 21-hydroxylase system

The 21-hydroxylase activity of microsomes isolated from bovine adrenal cortex have been assayed using [21-3H]17-hydroxypregnenolone and [1,2-3H]17-hydroxyprogesterone as substrates. When the assays are performed in the presence of an NADH regenerating system, to inhibit steroid 3 beta-hydroxy isomerase-dehydrogenase activity, the microsomes oxidize the 3 beta-hydroxy-5-ene steroid at a rate of 0.37 nmol/min.nmol cytochrome P-450 and the 3-keto-4-ene steroid at a rate of 6.4 nmol/min.nmol. When the microsomes are solubilized with Triton CF-54 they lose the ability to oxidize the 3-hydroxy-5-ene steroid, while the specific activity of the microsomes for the 3-keto-4-ene steroid is enhanced 3-fold. In contrast, when the microsomes are solubilized with sodium cholate, their specific activity towards the 4-ene steroid is decreased by 50% while the specific activity for a low concentration of the 5-ene steroid, 1 microM, is unchanged. In addition, when the oxidations of the labeled steroids (at 1 microM) by the microsomes, are examined in the presence of unlabeled 17-hydroxyprogesterone (at 20 microM) the oxidation of the 3-keto-4-ene steroid is inhibited by 92% while the oxidation of the 3 beta-hydroxy-5-ene steroid is only inhibited by 20%. These results all suggest that there are at least two 21-hydroxylases in bovine adrenal tissue, one of which can utilize the 3-keto-4-ene steroids only, the other of which, in addition, can utilize the 3 beta-hydroxy-5-ene steroids as substrates.     

When two is better than one

Gene duplication and divergence has long been considered an important route to adaptation and phenotypic evolution. Reporting in Nature, Hittinger and Carroll (2007) provide the first clear example of adaptations in both regulatory regions and protein-coding regions after gene duplication. This combination of evolutionary changes appears to have resolved an adaptive conflict, leading to increased organismal fitness.     

Why genomics is more than genomes

A report on the 2004 meeting on Molecular Genetics of Bacteria and Bacteriophages, Cold Spring Harbor, USA, 25-29 August 2004.     

Bilateral olfaction: two is better than one for navigation

Do animals require bilateral input to track odors? A recent study reveals that fruit fly larvae can localize odor sources using unilateral inputs from a single functional sensory neuron, but that an enhanced signal-to-noise ratio provided by dual inputs is helpful in more challenging environments.     

A little bit is better than nothing: the incomplete parthenogenesis of salamanders,frogs and fish

A re-examination of the mitochondrial genomes of unisexual salamander lineages, published in BMC Evolutionary Biology, shows them to be the oldest unisexual vertebrates known, having been around for 5 million years. This presents a challenge to the prediction that lack of genetic recombination is a fast track to extinction.     

How much is there really? Why stereology is essential in lung morphometry.

Quantitative data on lung structure are essential to set up structure-function models for assessing the functional performance of the lung or to make statistically valid comparisons in experimental morphology, physiology, or pathology. The methods of choice for microscopy-based lung morphometry are those of stereology, the science of quantitative characterization of irregular three-dimensional objects on the basis of measurements made on two-dimensional sections. From a practical perspective, stereology is an assumption-free set of methods of unbiased sampling with geometric probes, based on a solid mathematical foundation. Here, we discuss the pitfalls of lung morphometry and present solutions, from specimen preparation to the sampling scheme in multiple stages, for obtaining unbiased estimates of morphometric parameters such as volumes, surfaces, lengths, and numbers. This is demonstrated on various examples. Stereological methods are accurate, efficient, simple, and transparent; the precision of the estimates depends on the size and distribution of the sample. For obtaining quantitative data on lung structure at all microscopic levels, state-of-the-art stereology is the gold standard.     

Complete culture medium is better than low folate medium for detecting increased chromosome aberrations in smokers in 48-h lymphocyte cultures

We compared chromosome breakage in parallel, 48-h lymphocyte cultures established from smokers and nonsmokers using minimal essential medium (MEM) and MEM without folate (MEM-FA). There was a statistically significant, higher frequency of aberrations for smokers than for nonsmokers in cells cultured in MEM, but not in those cultured in MEM-FA. Thus, these data support the recommendation of the World Health Organization (1985) that population monitoring studies for exposure assessment should not use a low folate medium.     

Dimethylformamide is no better than glycerol for cryopreservation of canine semen

The objective of this study was to compare the effects of dimethylformamide (DMF) and glycerol in canine (Canis lupus familiaris) semen cryopreservation based on postthaw motility and velocity evaluated by computer-assisted sperm analysis (CASA) and the effects on subjective progressive motility, percentage of live sperm, and plasma membrane functional integrity. The semen was diluted in two steps with an egg-yolk Tris extender containing 6% glycerol or DMF, frozen in 0.25-mL straws, and stored in liquid nitrogen. Immediately after thawing, samples were accessed for subjective sperm motility, sperm membrane functional integrity, percentage of live sperm, and evaluation by CASA. There were differences (P < 0.05) between glycerol and DMF with regard to subjective progressive motility (43.1% vs. 21.5%), objective progressive motility (11.8% vs. 6.2%), velocity average pathway (31.1 vs. 23.1 μm/sec), and amplitude of lateral head (3.3 vs. 3.9 μm), which confirmed the efficiency of glycerol. In conclusion, objective analysis performed by CASA confirmed that no benefits were derived by using DMF to replace glycerol for cryopreservation of canine semen.     

An ascomycota coculture in batch bioreactor is better than polycultures for cellulase production

Efficient hydrolysis of holocellulose depends on a proper balance between cellulase (endoglucanase, exoglucanase, β-glucosidase) and xylanase activities. The present study aimed to induce the production of cellulases and xylanases using liquid cultures (one, two, three, and four fungal strains on the same bioreactor) of wild strains of Trichoderma harzianum, Aspergillus niger, and Fusarium oxysporum. The strains were identified by amplification and analysis of the ITS rDNA region and the obtained sequences were deposited in Genbank. Enzymes (endoglucanase, exoglucansae, β-glucosidase, and xylanase activities) and the profile of extracellular protein isoforms (SDS-PAGE) produced by different fungal combinations (N?=?14) were analyzed by Pearson’s correlation matrix and principal component analysis (PCA). According to our results, induction of endoglucanase (19.02%) and β-glucosidase (6.35%) were obtained after 4 days when A. niger and F. oxysporum were cocultured. The combination of A. niger–T. harzianum produced higher endoglucanase in a shorter time than monocultures. On the contrary, when more than two strains were cultured in the same reactor, the relationships of competition were established, trending to diminish the amount of enzymes and the extracellular protein isoforms produced. The xylanase production was sensible to stress produced by mixed cultures, decreasing their activity. This is important when the aim is to produce cellulase-free xylanase. In addition, exoglucanase activity did not change in the combinations tested.     

Modeling the signaling endosome hypothesis: Why a drive to the nucleus is better than a (random) walk

Background  

Information transfer from the plasma membrane to the nucleus is a universal cell biological property. Such information is generally encoded in the form of post-translationally modified protein messengers. Textbook signaling models typically depend upon the diffusion of molecular signals from the site of initiation at the plasma membrane to the site of effector function within the nucleus. However, such models fail to consider several critical constraints placed upon diffusion by the cellular milieu, including the likelihood of signal termination by dephosphorylation. In contrast, signaling associated with retrogradely transported membrane-bounded organelles such as endosomes provides a dephosphorylation-resistant mechanism for the vectorial transmission of molecular signals. We explore the relative efficiencies of signal diffusion versus retrograde transport of signaling endosomes.     

Leaf-swallowing in Nigerian chimpanzees: evidence for assumed self-medication

A field study in Gashaka, Nigeria, adds the fourth subspecies of chimpanzee, Pan troglodytes vellerosus, to the list of African ape populations in which leaf-swallowing occurs. Unchewed herbaceous leaves of Desmodium gangeticum (Leguminosae-Papilionoideae) were recovered in 4% of 299 faecal samples of wild chimpanzees and clumps of sharp-edged grass leaves in 2%. The ingestion is believed to serve self-medicatory purposes because the leaves had a rough surface or were sharp-edged (which could be related to parasite control through a self-induced increase of gut motility), were not chewed, were excreted whole (indicating that they were not ingested for nutritional purposes), leaf-swallowing was restricted to the rainy season (during which time parasite re-infections are more common), and parasitic worms (Oesophagostomum stephanostomum) were found together with the leaves. Submitted to: Primates, May 2005; revision: 26 Oct 2005