mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Inactivation of avian progesterone receptor binding to ATP-Sepharose by pyridoxal 5'-phosphate

The affinity of progesterone receptor from hen oviduct for ATP-Sepharose was diminished by preincubation with pyridoxal 5′-phosphate. This effect was specific for pyridoxal 5′-phosphate since the related compounds, pyridoxal, pyridoxine, pyridoxamine and pyridoxamine 5′-phosphate, were not effectors. The inactivation was easily reversed by the addition of the primary amine, Tris. However, in the presence of the reducing agent NaBH₄, the inhibitory effect of pyridoxal 5′-phosphate was irreversible. The results suggest that pyridoxal 5′-phosphate forms a Schiff base with a critical amino group, presumably at the nucleotide binding site of the progesterone receptor.     

Metabolic adaptations for isopod specialization in three species of Dysdera spiders from the Canary Islands

The spider genus Dysdera is considered to comprise specialist isopod feeders, although the degree of specialization varies between species, depending on morphological (shape of chelicerae), behavioural (attack tactics) and metabolic (food quality of prey) adaptations. Dysdera has radiated extensively in the Canary Islands (currently 47 endemic species are described) and codistributed species have different cheliceral shapes and body sizes indicating different feeding niches. In the present study, we investigate the existence of metabolic adaptations to feeding on isopods by three endemic species (Dysdera insulana Simon, Dysdera macra Simon and Dysdera verneaui Simon) from Tenerife. We hypothesize that there is enhanced extraction efficiency of fundamental macronutrients from isopods compared with control prey in species with special morphological and behavioural adaptations for this prey type. We measure quantitatively spider growth, dry mass consumption, lipid and nitrogen consumption, and calculate growth efficiency and efficiency of utilization of dry mass, lipid and nitrogen. The results show that all three species are able to utilize both prey types, indicating that none of them are strict isopod specialist. Dysdera insulana shows enhanced growth efficiency and D. macra shows enhanced nitrogen extraction efficiency compared with D. verneaui when feeding on Porcellio rather than on Musca. Both traits indicate likely adaptations for the utilization of isopods. Spider species, sex and prey type all affect lipid and nitrogen extraction efficiencies, indicating that spiders do not simply extract nutrients in the proportions available. The results support the hypothesis that adaptations for enhanced digestion of focal prey evolve in species that already have adaptations for enhanced capture success.     

A Gene Transfer Agent and a Dynamic Repertoire of Secretion Systems Hold the Keys to the Explosive Radiation of the Emerging Pathogen Bartonella

Gene transfer agents (GTAs) randomly transfer short fragments of a bacterial genome. A novel putative GTA was recently discovered in the mouse-infecting bacterium Bartonella grahamii. Although GTAs are widespread in phylogenetically diverse bacteria, their role in evolution is largely unknown. Here, we present a comparative analysis of 16 Bartonella genomes ranging from 1.4 to 2.6 Mb in size, including six novel genomes from Bartonella isolated from a cow, two moose, two dogs, and a kangaroo. A phylogenetic tree inferred from 428 orthologous core genes indicates that the deadly human pathogen B. bacilliformis is related to the ruminant-adapted clade, rather than being the earliest diverging species in the genus as previously thought. A gene flux analysis identified 12 genes for a GTA and a phage-derived origin of replication as the most conserved innovations. These are located in a region of a few hundred kb that also contains 8 insertions of gene clusters for type III, IV, and V secretion systems, and genes for putatively secreted molecules such as cholera-like toxins. The phylogenies indicate a recent transfer of seven genes in the virB gene cluster for a type IV secretion system from a cat-adapted B. henselae to a dog-adapted B. vinsonii strain. We show that the B. henselae GTA is functional and can transfer genes in vitro. We suggest that the maintenance of the GTA is driven by selection to increase the likelihood of horizontal gene transfer and argue that this process is beneficial at the population level, by facilitating adaptive evolution of the host-adaptation systems and thereby expansion of the host range size. The process counters gene loss and forces all cells to contribute to the production of the GTA and the secreted molecules. The results advance our understanding of the role that GTAs play for the evolution of bacterial genomes.     

Blockade of TrkB but not p75NTR activates a subpopulation of quiescent neural precursor cells and enhances neurogenesis in the adult mouse hippocampus

Brain‐derived neurotrophic factor (BDNF) signaling plays a major role in the regulation of hippocampal neurogenesis in the adult brain. While the majority of studies suggest that this is due to its effect on the survival and differentiation of newborn neurons, it remains unclear whether this signaling directly regulates neural precursor cell (NPC) activity and which of its two receptors, TrkB or the p75 neurotrophin receptor (p75^NTR) mediates this effect. Here, we examined both the RNA and protein expression of these receptors and found that TrkB but not p75^NTR receptors are expressed by hippocampal NPCs in the adult mouse brain. Using a clonal neurosphere assay, we demonstrate that pharmacological blockade of TrkB receptors directly activates a distinct subpopulation of NPCs. Moreover, we show that administration of ANA‐12, a TrkB‐selective antagonist, in vivo either by systemic intraperitoneal injection or by direct infusion within the hippocampus leads to an increase in the production of new neurons. In contrast, we found that NPC‐specific knockout of p75^NTR had no effect on the proliferation of NPCs and did not alter neurogenesis in the adult hippocampus. Collectively, these results demonstrate a novel role of TrkB receptors in directly regulating the activity of a subset of hippocampal NPCs and suggest that the transient blockade of these receptors could be used to enhance adult hippocampal neurogenesis.     

Food and specific macronutrient limitation in an assemblage of predatory beetles

Habitats vary in food resources with carnivores often being prey limited, but it is unclear whether habitats facilitate a nutritionally balanced diet. Two paradigms in nutritional ecology, ecological stoichiometry and nutritional geometry, predict that carnivores are limited mainly by protein or lipid, respectively. Using the carabid beetle Anchomenus dorsalis and 10 other predatory beetles from agricultural fields, we developed and tested two simple procedures for quantifying macronutrient‐specific habitat conditions without requiring information about the natural prey. Both procedures assume that predators forage for nutrients rather than specific prey. Our results show that 10 of 11 species were food limited. Five species were lipid limited and one species was protein limited in the field. Co‐existing predator species showed considerable segregation of fundamental macronutritional niches. A linear relationship between specific nutrient limitation and the target lipid:protein (L:P) intake ratio indicates that species with high L:P target are more protein limited while species with low L:P target are more lipid limited. The study illustrates how species within a natural assemblage vary in nutritional niche and in specific nutrient limitation.     

Interaction of murine progesterone receptors with specific monoclonal antibodies to the avian progesterone receptor

Monoclonal antibodies raised against purified chicken progesterone receptor (PgR) have been described and characterized recently. In this study we have screened these antibodies for cross-reactivity with murine PgR. Of the six anti-PgR antibodies tested, one (alpha PR6) precipitates murine PgR in an assay using protein A-sepharose as an absorbent for the antibody. The antibody is specific for PgR and does not react with the estrogen receptor or the glucocorticoid receptor in the same cytosol. In immunoblot experiments, both alpha PR6 and alpha PR11 recognize a 115,000 Da protein, however, alpha PR11 gives a weaker signal than alpha PR6. In photoaffinity labeling experiments, a 115,000 Da and an 83,000 Da protein covalently bind tritiated R5020 in a receptor-specific way. We conclude that the alpha PR6 antibody can be used as a tool to study the structure and function of the murine PgR.     

Prevention and correction of temporal hair loss in rhytidectomy

Routine incisions in the temporal area for rhytidectomy often remove hair-bearing skin anterior to the ear. This results in a cosmetic deformity, making the surgical intervention clearly visible. This is especially problematic for revision rhytidectomy or for patients with naturally high hairlines. This article describes a systematic approach to the temporal hairline and introduces a novel, hair-bearing, transposition flap that corrects iatrogenic loss of the preauricular tuft of hair.     

Influence of oxygen tension on myocardial performance. Evaluation by tissue Doppler imaging

Background

Endothelial function in hypercholesterolemic rabbits is usually evaluated ex vivo on isolated aortic rings. In vivo evaluation requires invasive imaging procedures that cannot be repeated serially.

Aim

We evaluated a non-invasive ultrasound technique to assess early endothelial function in rabbits and compare data with ex vivo measurements.

Methods

Twenty-four rabbits (fed with a cholesterol diet (0.5%) for 2 to 8 weeks) were given progressive infusions of acetylcholine (0.05–0.5 μg/kg/min) and their endothelial function was assessed in vivo by transcutaneous vascular ultrasound of the abdominal aorta. Ex vivo endothelial function was evaluated on isolated aortic rings and compared to in vivo data.

Results

Significant endothelial dysfunction was demonstrated in hypercholesterolemic animals as early as 2 weeks after beginning the cholesterol diet (aortic cross-sectional area variation: -2.9% vs. +4% for controls, p < 0.05). Unexpectedly, response to acetylcholine at 8 weeks was more variable. Endothelial function improved in 5 rabbits while 2 rabbits regained a normal endothelial function. These data corroborated well with ex vivo results.

Conclusion

Endothelial function can be evaluated non-invasively in vivo by transcutaneous vascular ultrasound of the abdominal aorta in the rabbit and results correlate well with ex vivo data.     

Bone bank service in Odense, Denmark. Audit of the first ten years with bone banking at the Department of Orthopaedics, Odense University Hospital

There has been an increase in the demand for allograft bone in recentyears. The Odense University Hospital bone bank has been in function since1990,and this paper outlines our results during the 10 year period 1990–1999.Potential donors were screened by contemporary banking techniques which includea social history, donor serum tests for HIV, hepatitis B and C, and graftmicrobiology. The bones were stored at –80 °C. No typeofsecondary sterilisation was made. 423 femoral heads were approved and donatedto300 patients,1–6 heads/operation. The allografts have been used mainly toreconstruct defects at revision hip arthroplasty (34%), and for fracturesurgery(24%). 7 % of all transplanted patients were reoperated because of infection.Inthe hip revision group the infection rate was 4 %. There were no cases ofdisease transmission. During the 10 year period there was a change in theclinical use of the allografts. In the first years the allografts were mainlyused for spinal fusion surgery, but today the majority are used in hip revisionand fracture surgery. The clinical results correspond to those reported inlarger international series.