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At least 1,333 records · Page 74Linked to original sources
PubMed1991

The distribution of neuropeptides in the ocular tissues of several mammals: a comparative study.

1. The distribution of several neuropeptides (vasoactive intestinal peptide, substance P, somatostatin and neurotensin) was assessed in ocular tissues from the cow, sheep, rabbit and rat. 2. Vasoactive intestinal peptide was most abundant in the choroid and sclera in all species except the rat. Substance P was most abundant in the retina of cow and rat and in the iris/ciliary body of sheep and rabbit. Somatostatin and neurotensin were most abundant in the retina of all species examined. 3. Regulatory peptides thus display distinct regional distributions within the ocular tissues of a single species of mammal and, in addition, exhibit interspecific variation.

Animals↗
PubMed1994

Comparative genome mapping in mammals.

The mammals all have similar amounts of DNA, usually distributed over 40-60 chromosomes. Most of the differences in karyotype are related to fixation of less than 100 reciprocal translocations which have occurred over less than 100 million years. This allows the genome mapping of the main laboratory and farmyard species to help, and to be helped by, mapping of the human genome.

Animals↗
PubMed1994

Regeneration of hair cells in the vestibulocochlear system of birds and mammals.

Regeneration of hair cells leads to a structural and functional recovery in the mature avian vestibular and auditory sensory epithelia. This regeneration replaces hair cells that have been lost as a result of noise damage, ototoxic drug poisoning, or other trauma. Recent findings suggest that it may be possible to induce a similar mechanism for repair in the vestibular and auditory epithelia of mammals, including humans.

Animals↗
PubMed1995

Generation of respiratory rhythm and pattern in mammals: insights from developmental studies.

Our understanding of the cellular, synaptic and network mechanisms underlying respiratory rhythm generation in mammals is progressing rapidly as researchers focus on a site hypothesized as the source of rhythm generation, the preBötzinger complex, in the rostral ventrolateral medulla. Furthermore, ontogenetic and modulatory factors affecting respiratory neuronal circuits are receiving considerable attention, as postnatal development of motor systems becomes increasingly apparent.

Animals↗
PubMed2006

Long-term reduction of Trypanosoma cruzi infection in sylvatic mammals following deforestation and sustained vector surveillance in northwestern Argentina.

Long-term variations in the dynamics and intensity of sylvatic transmission of Trypanosoma cruzi were investigated around eight rural villages in the semiarid Argentine Chaco in 2002-2004 and compared to data collected locally in 1984-1991. Of 501 wild mammals from 13 identified species examined by xenodiagnosis, only 3 (7.9%) of 38 Didelphis albiventris opossums and 1 (1.1%) of 91 Conepatus chinga skunks were infected by T. cruzi. The period prevalence in opossums was four-fold lower in 2002-2004 than in 1984-1991 (32-36%). The infection prevalence of skunks also decreased five-fold from 4.1-5.6% in 1984-1991 to 1.1% in 2002-2004. Infection in opossums increased with age and from summer to spring in both study periods. The force of infection per 100 opossum-months after weaning declined more than six-fold from 8.2 in 1988-1991 to 1.2 in 2002-2004. Opossums were mainly infected by T. cruzi lineage I and secondarily by lineage IId in 1984-1991, and only by T. cruzi I in 2002-2004; skunks were infected by T. cruzi IId in 1984-1991 and by IIc in 2002-2004. The striking decline of T. cruzi infection in opossums and skunks occurred in parallel to community-wide insecticide spraying followed by selective sprays leading to very low densities of infected Triatoma infestans in domestic and peridomestic habitats since 1992; to massive deforestation around one of the villages or selective extraction of older trees, and apparent reductions in opossum abundance jointly with increases in foxes and skunks. These factors may underlie the dramatic decrease of T. cruzi infection in wild reservoir hosts.

Animal Diseases↗
PubMed2004

Characterization of the zebrafish vascular endothelial growth factor A gene: comparison with vegf-A genes in mammals and Fugu.

Vascular endothelial growth factor (VEGF-A) is a key angiogenic growth factor which regulates vertebrate embryonic vascularization, adult physiology such as wound healing and reproduction as well as many human diseases. To understand the evolution and regulation of this gene in vertebrates, we have isolated and characterized the zebrafish vegf-A gene and compared it with VEGF-A genes of human, mouse as well as an in silico isolated VEGF-A homologue from pufferfish. Our results indicate that the zebrafish vegf-A gene is organized similarly to mammalian and Fugu VEGF-A genes, with eight exons interrupted by seven introns. However, zebrafish vegf-A introns are generally larger than mammalian introns while Fugu VEGF-A introns are much smaller. Furthermore, zebrafish exon 6 (z6) has a unique sequence while Fugu's exon 6 is highly homologous to the mammalian counterparts. Alternative splicing generates multiple vegf-A mRNA isoforms in zebrafish with Vegf(121) as the dominant isoform in adult and Vegf(165) as the dominant isoform in early embryos. The exon z6 containing isoform Vegf(12345z678) is only detected in heart, muscle, and early embryos while another isoform Vegf-A(1234577)(a)(8) is only detected in heart. Furthermore, no conserved 5' flanking sequences between zebrafish and Fugu were observed while numerous conserved regions exist between human and mouse in this area. These results suggest both conserved and diverged functions of VEGF-A from fish to mammals since the separation of these two groups from their common ancestor about 450 million years ago and a diverged regulation of this gene since the separation of zebrafish from Fugu. These data will be valuable for future studies of VEGF-A gene regulation and function in different vertebrates.

Amino Acid Sequence↗
PubMed2006

Biosynthesis of heme in mammals.

Most iron in mammalian systems is routed to mitochondria to serve as a substrate for ferrochelatase. Ferrochelatase inserts iron into protoporphyrin IX to form heme which is incorporated into hemoglobin and cytochromes, the dominant hemoproteins in mammals. Tissue-specific regulatory features characterize the heme biosynthetic pathway. In erythroid cells, regulation is mediated by erythroid-specific transcription factors and the availability of iron as Fe/S clusters. In non-erythroid cells the pathway is regulated by heme-mediated feedback inhibition. All of the enzymes in the heme biosynthetic pathway have been crystallized and the crystal structures have permitted detailed analyses of enzyme mechanisms. All of the genes encoding the heme biosynthetic enzymes have been cloned and mutations of these genes are responsible for a group of human disorders designated the porphyrias and for X-linked sideroblastic anemia. The biochemistry, structural biology and the mechanisms of tissue-specific regulation are presented in this review along with the key features of the porphyric disorders.

Animals↗
PubMed2005

Circadian regulation of sleep in mammals: role of the suprachiasmatic nucleus.

Despite significant progress in elucidating the molecular basis for circadian oscillations, the neural mechanisms by which the circadian clock organizes daily rhythms of behavioral state in mammals remain poorly understood. The objective of this review is to critically evaluate a conceptual model that views sleep expression as the outcome of opponent processes-a circadian clock-dependent alerting process that opposes sleep during the daily wake period, and a homeostatic process by which sleep drive builds during waking and is dissipated during sleep after circadian alerting declines. This model is based primarily on the evidence that in a diurnal primate, the squirrel monkey (Saimiri sciureus), ablation of the master circadian clock (the suprachiasmatic nucleus; SCN) induces a significant expansion of total daily sleep duration and a reduction in sleep latency in the dark. According to this model, the circadian clock actively promotes wake but only passively gates sleep; thus, loss of circadian clock alerting by SCN ablation impairs the ability to sustain wakefulness and causes sleep to expand. For comparison, two additional conceptual models are described, one in which the circadian clock actively promotes sleep but not wake, and a third in which the circadian clock actively promotes both sleep and wake, at different circadian phases. Sleep in intact and SCN-damaged rodents and humans is first reviewed, to determine how well the data fit these conceptual models. Neuroanatomical and neurophysiological studies are then reviewed, to examine the evidence for direct and indirect interactions between the SCN circadian clock and sleep-wake circuits. Finally, sleep in SCN-ablated squirrel monkeys is re-examined, to consider its compatibility with alternative models of circadian regulation of sleep. In aggregate, the behavioral and neurobiological evidence suggests that in rodents and humans, the circadian clock actively promotes both wake and sleep, at different phases of the circadian cycle. The hypersomnia of SCN-ablated squirrel monkeys is unique in magnitude, but is not incompatible with a role for the SCN pacemaker in actively promoting sleep.

Animals↗
PubMed2006

The complex multidomain organization of SCO-spondin protein is highly conserved in mammals.

The multidomain organization of SCO-spondin protein is a special feature of the chordate phylum. This protein is expressed in the central nervous system (CNS) from the time a dorsal neural tube appears in the course of phylogenetical evolution. With the advance of the systematic whole genomes sequencing, we were able to determine the SCO-spondin amino acid sequence in four mammalian species using the Wise2 software. From the ClustalW alignment of bovine (Bos taurus), human (Homo sapiens), murine (Mus musculus) and rat (Rattus norvegicus) proteins, a consensus sequence for mammalian SCO-spondin was determined and further validated with the dog (Canis familiaris) SCO-spondin sequence. The analysis of this consensus sequence is consistent with a very high degree of conservation in the amino acids composition and multidomain organization of SCO-spondin in mammals. In addition, the identification of conserved domains, namely, Emilin (EMI), von Willebrand factor D (vWD), low-density lipoprotein receptor type A (LDLrA) domains, SCO repeats (SCOR), thrombospondin type 1 repeats (TSR), a coagulation factor 5/8 type C (FA5-8C) or discoidin motif and a C-terminal cystine knot (CTCK) domain, provides a greater insight into the putative function of this multidomain protein. SCO-spondin belongs to the TSR superfamily given the presence of a great number of TSR (26). A finer classification of the TSR motifs in groups 1, 2 and 3 is proposed on the basis of different cysteine patterns. Interestingly, group 2 TSR are present in a number of CNS developmental proteins including R-spondins, F-spondins and Mindins.

Animals↗
PubMed2005

Molecular mechanism of the photoperiodic response of gonads in birds and mammals.

Appropriate timing of various seasonal processes is crucial to the survival and reproductive success of animals living in temperate regions. When seasonally breeding animals are subjected to annual changes in day length, dramatic changes in neuroendocrine-gonadal activity take place. However, the molecular mechanism underlying the photoperiodic response of gonads remains unknown for all living organisms. It is well known that a circadian clock is somehow involved in the regulation of photoperiodism. Recently, rhythmic expression of circadian clock genes was observed in the mediobasal hypothalamus (MBH) of Japanese quail. The MBH is believed to be the center for photoperiodism. In addition, long-day-induced hormone conversion of the prohormone thyroxine (T(4)) to the bioactive triiodothyronine (T(3)) by deiodinase in the MBH has been proven to be important to the photoperiodic response of the gonads. Although the regulating mechanism for the photoperiodic response of gonads in birds and mammals has long been considered to be quite different, the long-day-induced expression of the deiodinase gene in the hamster hypothalamus suggests the existence of a conserved regulatory mechanism in avian and mammalian photoperiodism.

Animals↗
PubMed2006

Marine mammal strandings in the New Caledonia region, Southwest Pacific.

Four hundred twenty three marine mammals, in 72 stranding events, were recorded between 1877 and 2005 in New Caledonia, the Loyalty Islands, and Vanuatu in the southwest Pacific. Sixteen species were represented in this count, including: minke whale, Balaenoptera acutorostrata (1 single stranding), sei whale, B. borealis (1 single stranding), blue whale, B. musculus (1 single stranding), humpback whale, Megaptera novaeangliae (2 single strandings), giant sperm whale, Physeter macrocephalus (18 single strandings, 2 pair strandings), pygmy sperm whale, Kogia breviceps (5 single strandings), dwarf sperm whale, K. sima (2 single strandings, 1 triple stranding), Blainville's beaked whale, Mesoplodon densirostris (2 single strandings), short-finned pilot whale, Globicephala macrorhynchus (4 strandings, 56 individuals), melon-headed whale, Peponocephala electra (1 single stranding and 2 mass strandings totalling 231 individuals), common dolphin, Delphinus delphis (1 single stranding), spinner dolphin, Stenella longirostris (1 pair stranding and 2 mass strandings of groups of approximately 30 individuals each), Indian Ocean bottlenose dolphin, Tursiops aduncus (2 single strandings), dugong, Dugong dugon (14 single strandings), and New Zealand fur seal, Arctocephalus forsteri (3 single strandings). A stranded rorqual identified as an Antarctic minke whale (B. bonaerensis), with coloration patterns that did not match known descriptions, was also reported. Sei whale was recorded for the first time in the tropical Southwest Pacific region and Antarctic minke whale, melon-headed whale, and Indian Ocean bottlenose dolphin were recorded for the first time in New Caledonia. Strandings of sperm whales were most frequent in the spring, but also occurred in autumn months, suggesting a seasonal pattern of occurrence possibly related to seasonal migration. One stranded humpback whale bore the scars of a killer whale's attack and one dugong was injured by a shark. Scars left by propellers were noted on several stranded animals including one Antarctic minke whale, one pygmy sperm whale, one dwarf sperm whale, and four dugongs. Collisions with vessels were suspected to be a frequent cause of death for dugong.

Animals↗
PubMed2006

Various domains of the B-cell regulatory molecule CD72 has diverged at different rates in mammals: cloning, transcription and mapping of porcine CD72.

We report the cloning of the porcine B-cell co-receptor CD72, as well as genomic mapping and examination of transcription. The B-cell receptor (BCR) complex mediates signalling upon antigen recognition by the membrane bound BCR. Several co-receptors modulate this signal positively or negatively. CD72 has been shown to be a negatively regulating BCR co-receptor. We isolated and sequenced three porcine CD72 transcript variants. Using a pig radiation hybrid panel we found the porcine CD72 gene to be located on chromosome 1q21-28 in a region syntenic to human chromosome 9. The porcine CD72 gene is highly transcribed in lymph node, thymus and lung tissues as well as in pulmonary alveolar macrophages. The predicted porcine CD72 polypeptide shows conservation of immunoreceptor tyrosine-based inhibitory motifs and an extracellular C-type lectin domain. Compared to CD72 sequences from other mammals as well as from chicken, the polypeptide is highly conserved in the intracellular part and much less conserved in the extracellular part. We suggest that this difference might be due to the different nature of ligands and the constrains on these to co-evolve.

Alternative Splicing↗
PubMed2006

The insulin signaling cascade from nematodes to mammals: insights into innate immunity of Anopheles mosquitoes to malaria parasite infection.

As revealed over the past 20 years, the insulin signaling cascade plays a central role in regulating immune and oxidative stress responses that affect the life spans of mammals and two model invertebrates, the nematode Caenorhabitis elegans and the fruit fly Drosophila melanogaster. In mosquitoes, insulin signaling regulates key steps in egg maturation and immunity and likely affects aging, although the latter has yet to be examined in detail. Reproduction, immunity and aging critically influence the capacity of mosquitoes to effectively transmit malaria parasites. Current work has demonstrated that molecules from the invading parasite and the blood meal elicit functional responses in female mosquitoes that are regulated through the insulin signaling pathway or by cross-talk with interacting pathways. Defining the details of these regulatory interactions presents significant challenges for future research, but will increase our understanding of mosquito/malaria parasite transmission and of the conservation of insulin signaling as a key regulatory nexus in animal biology.

Animals↗
PubMed2006

Divergence of hedgehog signal transduction mechanism between Drosophila and mammals.

The Hedgehog (Hh) signaling pathway has conserved roles in development of species ranging from Drosophila to humans. Responses to Hh are mediated by the transcription factor Cubitus interruptus (Ci; GLIs 1-3 in mammals), and constitutive activation of Hh target gene expression has been linked to several types of human cancer. In Drosophila, the kinesin-like protein Costal2 (Cos2), which associates directly with the Hh receptor component Smoothened (Smo), is essential for suppression of the transcriptional activity of Ci in the absence of ligand. Another protein, Suppressor of Fused (Su(Fu)), exerts a weak negative influence on Ci activity. Based on analysis of functional and sequence conservation of Cos2 orthologs, Su(Fu), Smo, and Ci/GLI proteins, we find here that Drosophila and mammalian Hh signaling mechanisms have diverged, and that, in mouse cells, major Cos2-like activities are absent and the inhibition of the Hh pathway in the absence of ligand critically depends on Su(Fu).

Amino Acid Sequence↗
PubMed2005

Preliminary screening of perfluorooctane sulfonate (PFOS) and other fluorochemicals in fish, birds and marine mammals from Greenland and the Faroe Islands.

Extensive screening analyses of perfluorooctane sulfonate (PFOS) and related perfluorinated compounds in biota samples from all over the world have identified PFOS as a global pollutant and have shown its bioaccumulation into higher trophic levels in the food chain. Perfluorinated compounds have been found in remote areas as the Arctic. In this study a preliminary screening of PFOS and related compounds has been performed in liver samples of fish, birds and marine mammals from Greenland and the Faroe Islands. PFOS was the predominant fluorochemical in the biota analyzed, followed by perfluorooctane sulfonamide (PFOSA). PFOS was found at concentrations above LOQ (10 ng/g wet weight) in 13 out of 16 samples from Greenland and in all samples from the Faroe Islands. The results from Greenland showed a biomagnification of PFOS along the marine food chain (shorthorn sculpin < ringed seal < polar bear). The greatest concentration of PFOS was found in liver of polar bear from east Greenland (mean: 1285 ng/g wet weight, n = 2). The geographical distribution of perfluorinated compounds in Greenland was similar to that of persistent organohalogenated compounds (OHCs), with the highest concentrations in east Greenland, indicating a similar geographical distribution to that of OHCs, with higher concentrations in east Greenland than in west Greenland.

Alkanesulfonic Acids↗
PubMed2006

Identification of highly brominated analogues of Q1 in marine mammals.

Three novel halogenated organic compounds (HOCs) have been identified in the blubber of marine mammals from coastal New England with the molecular formulae C(9)H(3)N(2)Br(6)Cl, C(9)H(3)N(2)Br(7), and C(9)H(4)N(2)Br(5)Cl. They were identified using high and low resolution gas chromatography mass spectrometry (GCMS) and appear to be highly brominated analogues of Q1, a heptachlorinated HOC suspected to be naturally produced. These compounds were found in Atlantic white sided dolphin (Lagenorhynchus acutus), bottlenose dolphin (Tursiops truncatus), common dolphin (Delphinus delphis), Risso's dolphin (Grampus griseus), harbor porpoise (Phocoena phocoena), beluga whale (Delphinapterus leucas), fin whale (Balaenoptera physalus), grey seal (Halichoerus grypus), harp seal (Phoca groenlandica) and a potential food source (Loligo pealei) with concentrations as high as 2.7 microg/g (lipid weight). The regiospecificity of C(9)H(3)N(2)Br(6)Cl is suggestive of a biogenic origin. Debromination of C(9)H(3)N(2)Br(6)Cl may be significant in the formation of C(9)H(4)N(2)Br(5)Cl.

Animals↗
PubMed2005

The insulin/IGF-1 signaling in mammals and its relevance to human longevity.

Hormones, like insulin and insulin-like growth factor 1 (IGF-1), are thought to be deeply involved with longevity. Lower species have been the source for most of our current knowledge on the role of the insulin/IGF-1 signaling in modulating lifespan. This hormonal system may have originated from a very early common ancestor and is involved in many functions that are necessary for metabolism, growth, and fertility in animal models like flies, nematodes and mammalians. Disruption of the insulin/IGF-1 receptor in nematodes and flies increases lifespan significantly. With evolution, mammals developed two well characterized hormonal systems: insulin and growth hormone (GH)/IGF-1, with different metabolic and developmental functions. Abnormalities in the insulin signaling pathway generate age-related diseases and increased mortality, whereas the GH/IGF-1 axis could potentially modulate longevity in many species. In this review we briefly describe the lifespan regulatory role of the insulin/IGF-1 signaling of nematodes, flies and rodent models and compare it with the human equivalent.

Animals↗