Brainstem mechanisms underlying feeding behaviors

The essential elements controlling trigeminal motoneurons during feeding lie between the trigeminal and facial motor nuclei. These include populations of neurons in the medial reticular formation and pre-motoneurons in the lateral brainstem that reorganize to generate various patterns. Orofacial sensory feedback, antidromic firing in spindle afferents and intrinsic properties of motoneurons also contribute to the final masticatory motor output.     

A deletion panel of the long arm of the X chromosome: subregional localization of 22 DNA probes

Summary Two males and two females with different but overlapping deletions on the proximal long arm of the X chromosomes have been investigated. Their karyotypes, which have been well characterized by high resolution banding techniques, are 46,Y,del(X)(pterq21.1:: q21.33qter); 46,Y,del(X) (pterq21.2::q21.31qter); 46,X,del(X) (pterq21.31::q24.3qter) and 46,X,del (X)(pterq21.1:). A deletion panel, which makes it possible to subdivide the long arm of the X chromosome into seven subregions, has been established using the genomic DNA from the four families, and applied to the fine subregional localization of the loci for 22 DNA probes. Based on the results obtained, the possible location of the loci in question has been narrowed down considerably, in some cases to an area of only 5% of the previously assigned region; hybridization to Southern blots of a panel with well-characterized chromosome deletions is thus a powerful means of localizing DNA probes, especially with respect to the X probes.Part of the results from this investigation were published at Human Gene Mapping 9 as abstracts     

Multiple chaperonins in bacteria – why so many?

A significant proportion of bacteria express two or more chaperonin genes. Chaperonins are a group of molecular chaperones, defined by sequence similarity, required for the folding of some cellular proteins. Chaperonin monomers have a mass of c . 60 kDa, and are typically found as large protein complexes containing 14 subunits arranged in two rings. The mechanism of action of the Escherichia coli GroEL protein has been studied in great detail. It acts by binding to unfolded proteins and enabling them to fold in a protected environment where they do not interact with any other proteins. GroEL can assist the folding of many proteins of different sizes, sequences, and structures, and homologues from many different bacteria can functionally replace GroEL in E. coli . What then are the functions of multiple chaperonins? Do they provide a mechanism for cells to increase their general chaperoning ability, or have they become specialized to take on specific novel cellular roles? Here I will review the genetic, biochemical, and phylogenetic evidence that has a bearing on this question, and show that there is good evidence for at least some specificity of function in multiple chaperonin genes.     

Does Plasminogen Activator Inhibitor-1 Drive Lymphangiogenesis?

The purpose of this study is to explore the function of plasminogen activator inhibitor-1 (PAI-1) during pathological lymphangiogenesis. PAI-1, the main physiological inhibitor of plasminogen activators is involved in pathological angiogenesis at least by controlling extracellular proteolysis and by regulating endothelial cell survival and migration. Protease system''s role in lymphangiogenesis is unknown yet. Thus, based on its important pro-angiogenic effect, we hypothesized that PAI-1 may regulate lymphangiogenesis associated at least with metastatic dissemination of cancer cells. To address this issue, we studied the impact of PAI-1 deficiency in various murine models of tumoral lymphangiogenesis. Wild-type PAI-1 proficient mice were used as controls. We provide for the first time evidence that PAI-1 is dispensable for tumoral lymphangiogenesis associated with breast cancers either induced by mammary carcinoma cell injection or spontaneously appearing in transgenic mice expressing the polyomavirus middle T antigen (PymT) under the control of a mouse mammary tumor virus long-terminal repeat promoter (MMTV-LTR). We also investigated inflammation-related lymphatic vessel recruitment by using two inflammatory models. PAI-1 deficiency did neither affect the development of lymphangioma nor burn-induced corneal lymphangiogenesis. These novel data suggest that vascular remodelling associated with lymphangiogenesis and angiogenesis involve different molecular determinants. PAI-1 does not appear as a potential therapeutic target to counteract pathological lymphangiogenesis.     

Late Pleistocene and Holocene whale remains (Cetacea) from Denmark and adjacent countries: Species,distribution, chronology,and trace element concentrations

We describe and review the subfossil whale bones (mammalian order Cetacea) material from the southern Scandinavian area, that is, Skagerrak, Kattegat, the inner Danish waters and the southwestern Baltic Sea. Fifteen species were identified from the subfossil records of which all, except for the bowhead whale (Balaena mysticetus), have also been encountered in the modern times. Fifty-one specimens were radiocarbon dated covering 12 of the subfossil species. The dates fell in three distinct clusters with a few specimens before the last glacial maximum (LGM), a large group between LGM and the Pleistocene/Holocene boundary (ca. 17.0–11.7 cal. kyr BP), and another large group from ca. 8.0 cal. kyr BP onward. Seventeen of the radiocarbon dated specimens have been subjected to trace element analysis by Instrumental Neutron Activation Analysis. Cross plots of the concentrations of Fe and Zn, and Fe and Co show that it is possible to distinguish crayfish eaters from fish/squid eaters. This can be used as a novel and independent method for the determination to species of whale remains of otherwise uncertain speciation.     

Ecophysiology of an Ammonia-Oxidizing Archaeon Adapted to Low-Salinity Habitats

Ammonia oxidation in marine and terrestrial ecosystems plays a pivotal role in the cycling of nitrogen and carbon. Recent discoveries have shown that ammonia-oxidizing archaea (AOA) are both abundant and diverse in these systems, yet very little is known about their physiology. Here we report a physiological analysis of a novel low-salinity-type AOA enriched from the San Francisco Bay estuary, Candidatus Nitrosoarchaeum limnia strain SFB1. N. limnia has a slower growth rate than Nitrosopumilus maritimus and Nitrososphaera viennensis EN76, the only pure AOA isolates described to date, but the growth rate is comparable to the growth of marine AOA enrichment cultures. The growth rate only slightly decreased when N. limnia was grown under lower-oxygen conditions (5.5?% oxygen in the headspace). Although N. limnia was capable of growth at 75?% of seawater salinity, there was a longer lag time, incomplete oxidation of ammonia to nitrite, and slower overall growth rate. Allylthiourea (ATU) only partially inhibited growth and ammonia oxidation by N. limnia at concentrations known to completely inhibit bacterial ammonia oxidation. Using electron microscopy, we confirmed the presence of flagella as suggested by various flagellar biosynthesis genes in the N. limnia genome. We demonstrate that N. limnia is representative of a low-salinity estuarine AOA ecotype and that more than 85?% of its proteins have highest identity to other coastal and estuarine metagenomic sequences. Our findings further highlight the physiology of N. limnia and help explain its ecological adaptation to low-salinity niches.     

Host-specificity of uropathogenic Escherichia coli depends on differences in binding specificity to Gal alpha 1-4Gal-containing isoreceptors.

Four G adhesins, cloned from uropathogenic Escherichia coli strains, were examined for binding to glycolipids and various eukaryotic cells. PapGAD110 and PapGIA2 showed virtually identical binding patterns to Gal alpha 1-4Gal-containing glycolipids, while PapGJ96 differed slightly and PrsGJ96 markedly with respect to the effect of neighbouring groups on the binding. Their hemagglutination patterns confirmed the existence of three receptor-binding specificities. While the PapG adhesins bound to uroepithelial cells from man (T24) but not to those from the dog (MDCK II), the reverse was true of PrsG. These binding patterns were largely explained by the absence or presence of appropriate glycolipid isoreceptors, although the inability of the PapG adhesins to bind MDCK II cells was attributed to an inappropriate presentation of their receptor epitopes. The high prevalence of PrsG-like specificities observed among wild-type dog uropathogenic E. coli isolates, together with the determined isoreceptor composition of human and dog kidney target tissues, suggest variation in receptor specificity as a mechanism for shifting host specificity, and that this variation has evolved in response to the topography of the host cellular receptors. The receptor-binding half proposed for the predicted amino acid sequences of the four G adhesins and the corresponding adhesin of one of the dog E. coli isolates varied considerably among the three receptor-binding groups of adhesins, but only little within each group.     

Breakdown in the Process of Incipient Speciation in Anopheles gambiae

Understanding genetic causes and effects of speciation in sympatric populations of sexually reproducing eukaryotes is challenging, controversial, and of practical importance for controlling rapidly evolving pests and pathogens. The major African malaria vector mosquito Anopheles gambiae sensu stricto (s.s.) is considered to contain two incipient species with strong reproductive isolation, hybrids between the M and S molecular forms being very rare. Following recent observations of higher proportions of hybrid forms at a few sites in West Africa, we conducted new surveys of 12 sites in four contiguous countries (The Gambia, Senegal, Guinea-Bissau, and Republic of Guinea). Identification and genotyping of 3499 A. gambiae s.s. revealed high frequencies of M/S hybrid forms at each site, ranging from 5 to 42%, and a large spectrum of inbreeding coefficient values from 0.11 to 0.76, spanning most of the range expected between the alternative extremes of panmixia and assortative mating. Year-round sampling over 2 years at one of the sites in The Gambia showed that M/S hybrid forms had similar relative frequencies throughout periods of marked seasonal variation in mosquito breeding and abundance. Genome-wide scans with an Affymetrix high-density single-nucleotide polymorphism (SNP) microarray enabled replicate comparisons of pools of different molecular forms, in three separate populations. These showed strong differentiation between M and S forms only in the pericentromeric region of the X chromosome that contains the molecular form-specific marker locus, with only a few other loci showing minor differences. In the X chromosome, the M/S hybrid forms were more differentiated from M than from S forms, supporting a hypothesis of asymmetric introgression and backcrossing.     

PECAM1+/Sca1+/CD38+ Vascular Cells Transform into Myofibroblast-Like Cells in Skin Wound Repair

Skin injury induces the formation of new blood vessels by activating the vasculature in order to restore tissue homeostasis. Vascular cells may also differentiate into matrix-secreting contractile myofibroblasts to promote wound closure. Here, we characterize a PECAM1⁺/Sca1⁺ vascular cell population in mouse skin, which is highly enriched in wounds at the peak of neoangiogenesis and myofibroblast formation. These cells express endothelial and perivascular markers and present the receptor CD38 on their surface. PECAM1⁺/Sca1⁺/CD38⁺ cells proliferate upon wounding and could give rise to α-SMA⁺ myofibroblast-like cells. CD38 stimulation in immunodeficient mice reduced the wound size at the peak of neoangiogenesis and myofibroblast formation. In humans a corresponding cell population was identified, which was enriched in sprouting vessels of basal cell carcinoma biopsies. The results indicate that PECAM1⁺/Sca1⁺/CD38⁺ vascular cells could proliferate and differentiate into myofibroblast-like cells in wound repair. Moreover, CD38 signaling modulates PECAM1⁺/Sca1⁺/CD38⁺ cell activation in the healing process implying CD38 as a target for anti-angiogenic therapies in human basal cell carcinoma.