排序方式: 共有46条查询结果,搜索用时 328 毫秒
1.
2.
Guerrera William Sleeman Jonathan M. Jasper Ssebide B. Pace Lonny B. Ichinose Travers Y. Reif John S. 《International journal of primatology》2003,24(1):197-207
There has been increasing contact between mountain gorillas (Gorilla gorilla beringei) and the human population surrounding Bwindi Impenetrable Forest National Park (BIFNP) in Uganda. Due to the close taxonomic relationship between humans and gorillas there is potential for disease transmission between them. Preventing the introduction or spread of transmissible diseases to the gorillas is essential to protect them. We interviewed 301 villagers living in close proximity to BIFNP with a medical questionnaire in July, 2000. We collected information on demographics, vaccination and health history, and human/gorilla interaction. Our objectives were to estimate the prevalence of several diseases in the human population and to evaluate the risk of anthropozoonotic transmission from humans to gorillas. We found a high prevalence of disease symptoms such as coughing (72.1%) and fever (56.1%) compatible with acute infectious diseases; over half of the respondents (59.1%) had a specific disease diagnosis within the 6 mo preceding the study. We compared villagers who had visual contact with gorillas in the 6 mo preceding the study (53.5%) to villagers who had no visual contact (46.5%). Men were 2.3 times more likely than women to have visual contact with gorillas. In general, the frequency of disease history and symptoms was similar for people with and without contact. The high prevalence of acute infectious diseases in the population surrounding BIFNP and the high rate of contact with gorillas creates the potential for anthropozoonotic disease transmission. 相似文献
3.
The deep ocean greater than 1 km covers the majority of the earth''s surface. Interspersed on the abyssal plains and continental slope are an estimated 14000 seamounts, topographic features extending 1000 m off the seafloor. A variety of hypotheses are posited that suggest the ecological, evolutionary, and oceanographic processes on seamounts differ from those governing the surrounding deep sea. The most prominent and oldest of these hypotheses, the seamount endemicity hypothesis (SMEH), states that seamounts possess a set of isolating mechanisms that produce highly endemic faunas. Here, we constructed a faunal inventory for Davidson Seamount, the first bathymetric feature to be characterized as a ‘seamount’, residing 120 km off the central California coast in approximately 3600 m of water (Fig 1). We find little support for the SMEH among megafauna of a Northeast Pacific seamount; instead, finding an assemblage of species that also occurs on adjacent continental margins. A large percentage of these species are also cosmopolitan with ranges extending over much of the Pacific Ocean Basin. Despite the similarity in composition between the seamount and non-seamount communities, we provide preliminary evidence that seamount communities may be structured differently and potentially serve as source of larvae for suboptimal, non-seamount habitats.Open in a separate windowFigure 1Bathymetric map of the Central California Coast with Monterey Canyon and Davidson Seamount. 相似文献
4.
Kenneth R. Hallows Huamin Wang Robert S. Edinger Michael B. Butterworth Nicholas M. Oyster Hui Li Jochen Buck Lonny R. Levin John P. Johnson N��ria M. Pastor-Soler 《The Journal of biological chemistry》2009,284(9):5774-5783
Alkalosis impairs the natriuretic response to diuretics, but the underlying
mechanisms are unclear. The soluble adenylyl cyclase (sAC) is a chemosensor
that mediates bicarbonate-dependent elevation of cAMP in intracellular
microdomains. We hypothesized that sAC may be an important regulator of
Na+ transport in the kidney. Confocal images of rat kidney revealed
specific immunolocalization of sAC in collecting duct cells, and immunoblots
confirmed sAC expression in mouse cortical collecting duct
(mpkCCDc14) cells. These cells exhibit aldosterone-stimulated
transepithelial Na+ currents that depend on both the apical
epithelial Na+ channel (ENaC) and basolateral
Na+,K+-ATPase. RNA interference-mediated 60-70%
knockdown of sAC expression comparably inhibited basal transepithelial short
circuit currents (Isc) in mpkCCDc14 cells.
Moreover, the sAC inhibitors KH7 and 2-hydroxyestradiol reduced
Isc in these cells by 50-60% within 30 min.
8-Bromoadenosine-3′,5′-cyclic-monophosphate substantially rescued
the KH7 inhibition of transepithelial Na+ current. Aldosterone
doubled ENaC-dependent Isc over 4 h, an effect that was
abolished in the presence of KH7. The sAC contribution to
Isc was unaffected with apical membrane nystatin-mediated
permeabilization, whereas the sAC-dependent Na+ current was fully
inhibited by basolateral ouabain treatment, suggesting that the
Na+,K+-ATPase, rather than ENaC, is the relevant
transporter target of sAC. Indeed, neither overexpression of sAC nor treatment
with KH7 modulated ENaC currents in Xenopus oocytes. ATPase and
biotinylation assays in mpkCCDc14 cells demonstrated that sAC
inhibition decreases catalytic activity rather than surface expression of the
Na+,K+-ATPase. In summary, these results suggest that
sAC regulates both basal and agonist-stimulated Na+ reabsorption in
the kidney collecting duct, acting to enhance
Na+,K+-ATPase activity.Maintenance of intracellular pH depends in part on the extracellular to
intracellular Na+ gradient, and elevation of intracellular
[Na+] can lead to acidification of the cytoplasm. It has been shown
that acidification of the cytoplasm of cells from frog skin and toad bladder
by increased partial pressure of CO2 reduces Na+
transport and permeability (1,
2). Conversely, the rise in
plasma bicarbonate caused by metabolic alkalosis with chronic diuretic use has
been shown to increase net renal Na+ reabsorption independently of
volume status, electrolyte depletion, and/or increased aldosterone secretion
(3,
4). However, the underlying
mechanisms involved in these phenomena remain unclear.The soluble adenylyl cyclase
(sAC)2 is a
chemosensor that mediates the elevation of cAMP in intracellular microdomains
(5-7).
Unlike transmembrane adenylyl cyclases (tmACs), sAC is insensitive to
regulation by forskolin or heterotrimeric G proteins
(8) and is directly activated
by elevations of intracellular calcium
(9,
10) and/or bicarbonate ions
(11). Thus, sAC mediates
localized intracellular increases in cAMP in response to variations in
bicarbonate levels or its closely related parameters, partial pressure of
CO2 and pH. Mammalian sAC is more similar to bicarbonate-regulated
cyanobacterial adenylyl cyclases than to other mammalian nucleotidyl cyclases,
which may indicate that there is a unifying mechanism for the regulation of
cAMP signaling by bicarbonate across biological systems. Although sAC appears
to be encoded by a single gene, there is significant isoform diversity for
this ubiquitously expressed enzyme
(11,
12) generated by alternative
splicing (reviewed in Ref.
13). sAC has been shown to
regulate the subcellular localization and/or activity of membrane transport
proteins such as the vacuolar H+-ATPase (V-ATPase) and cystic
fibrosis transmembrane conductance regulator in epithelial cells
(14,
15). Functional activity of
sAC has been reported in the kidney
(16), and sAC has been
localized to epithelial cells in the distal nephron
(14,
17).Given that natriuresis is decreased during metabolic alkalosis, when
bicarbonate is elevated, and Na+ reabsorption is impaired by high
partial pressure of CO2, we hypothesized that bicarbonate-regulated
sAC may play a key role in the regulation of transepithelial Na+
transport in the distal nephron. Reabsorption of Na+ in the kidney
and other epithelial tissues is mediated by the parallel operation of apical
ENaC and basolateral Na+,K+-ATPase, and both transport
proteins can be stimulated by cAMP via the cAMP-dependent protein kinase (PKA)
(18,
53). The aims of this study
were to investigate the role of sAC in the regulation of transepithelial
Na+ transport in the kidney through the use of specific sAC
inhibitors and electrophysiological measurements. We found that sAC inhibition
blocks transepithelial Na+ reabsorption in polarized
mpkCCDc14 cells under both basal and hormone-stimulated conditions.
Selective membrane permeabilization studies revealed that although ENaC
activity appears to be unaffected by sAC inhibition, flux through the
Na+,K+-ATPase is sensitive to sAC modulation. Inhibiting
sAC decreases ATPase activity without affecting plasma membrane expression of
the pump; thus, tonic sAC activity appears to be required for Na+
reabsorption in kidney collecting duct. 相似文献
5.
Two relatively low-copy plasmids of 9 and 16 kb were found to comprise the extrachromosomal DNA of a Paracoccus strain. Reduction of nitrate by plasmid-cured cells resulted in a significant intermediate nitrite accumulation as compared to wild-type cells. By examining nitrate reduction by transformants containing one of the two plasmids, it was found that nitrite accumulation was influenced by the 9.0-kb plasmid, designated as pYR1. Subcloning analysis showed that a 1.8-kb fragment of this plasmid affected nitrite accumulation. Sequence analysis of this fragment revealed the presence of five open reading frames. One of the six deduced proteins showed a strong homology to ABC transporters. 相似文献
6.
Stessin AM Zippin JH Kamenetsky M Hess KC Buck J Levin LR 《The Journal of biological chemistry》2006,281(25):17253-17258
Nerve growth factor (NGF) and the ubiquitous second messenger cyclic AMP (cAMP) are both implicated in neuronal differentiation. Multiple studies indicate that NGF signals to at least a subset of its targets via cAMP, but the link between NGF and cAMP has remained elusive. Here, we have described the use of small molecule inhibitors to differentiate between the two known sources of cAMP in mammalian cells, bicarbonate- and calcium-responsive soluble adenylyl cyclase (sAC) and G protein-regulated transmembrane adenylyl cyclases. These inhibitors, along with sAC-specific small interfering RNA, reveal that sAC is uniquely responsible for the NGF-elicited rise in cAMP and is essential for the NGF-induced activation of the small G protein Rap1 in PC12 cells. In contrast and as expected, transmembrane adenylyl cyclase-generated cAMP is responsible for Rap1 activation by the G protein-coupled receptor ligand PACAP (pituitary adenylyl cyclase-activating peptide). These results identify sAC as a mediator of NGF signaling and reveal the existence of distinct pathways leading to cAMP-dependent signal transduction. 相似文献
7.
Welton L. Lee Henry M. Reiswig William C. Austin Lonny Lundsten 《Invertebrate Biology》2012,131(4):259-284
Chondrocladia (Symmetrocladia) lyra subgen. nov., sp. nov., is described from northeast Pacific sites at Escanaba Ridge and Monterey Canyon at depths of 3316–3399 m. Two retrieved specimens are described in detail, while variations are described in ten photographed or videotaped specimens. The basic structure, termed a vane, is harp‐ or lyre‐shaped. From 1 to 6 vanes extend by radial growth from the organism's center. The orientation among the vanes is approximately equiangular, such that together they display pentaradiate, tetraradiate, triradiate, or biradiate symmetries. Each vane is formed by a horizontal stolon supporting a series of upright, equidistantly spaced branches each of which terminates at its apex in a swollen ball in all observed specimens except the paratype. Swellings occur midway along the branches in the holotype, but not in the paratype. A linear row of filaments project from the sides, front, and back of each branch, and also from the tops of each stolon. The terminal balls are the sites of spermatophore production and release; mid‐branch swellings are sites of oocyte maturation. The two megasclere spicule types have specific distributions; styles support rhizoids, stolons, and branches, while subtylostyles support filaments and terminal balls. Anchorate isochelae cover all surfaces. Enclosed crustacean prey on branches and stolons provide direct evidence of carnivory. The structure of the vanes maximizes surface area for passive suspension feeding. Increased surface area could also maximize spermatophore capture, with the sigmas projecting from the spermatophore surface being caught by projecting isochelae on filaments. Swellings on filaments are snared spermatophores, firmly fused to recipient tissues and undergoing destruction. Spermatophores on filaments are present in branch swellings containing early and mature oocytes. Oogenesis and maturation occur only in proximity to branch swellings, suggesting that development is induced by spermatophore reception. Symmetrical development of uniserial branched stolons (the vanes) characterized members of the new subgenus Symmetrocladia. 相似文献
8.
Selina J. Hein Lorenz H. Lehmann Mandy Kossack Lonny Juergensen Dieter Fuchs Hugo A. Katus David Hassel 《PloS one》2015,10(4)
Translucent zebrafish larvae represent an established model to analyze genetics of cardiac development and human cardiac disease. More recently adult zebrafish are utilized to evaluate mechanisms of cardiac regeneration and by benefiting from recent genome editing technologies, including TALEN and CRISPR, adult zebrafish are emerging as a valuable in vivo model to evaluate novel disease genes and specifically validate disease causing mutations and their underlying pathomechanisms. However, methods to sensitively and non-invasively assess cardiac morphology and performance in adult zebrafish are still limited. We here present a standardized examination protocol to broadly assess cardiac performance in adult zebrafish by advancing conventional echocardiography with modern speckle-tracking analyses. This allows accurate detection of changes in cardiac performance and further enables highly sensitive assessment of regional myocardial motion and deformation in high spatio-temporal resolution. Combining conventional echocardiography measurements with radial and longitudinal velocity, displacement, strain, strain rate and myocardial wall delay rates after myocardial cryoinjury permitted to non-invasively determine injury dimensions and to longitudinally follow functional recovery during cardiac regeneration. We show that functional recovery of cryoinjured hearts occurs in three distinct phases. Importantly, the regeneration process after cryoinjury extends far beyond the proposed 45 days described for ventricular resection with reconstitution of myocardial performance up to 180 days post-injury (dpi). The imaging modalities evaluated here allow sensitive cardiac phenotyping and contribute to further establish adult zebrafish as valuable cardiac disease model beyond the larval developmental stage. 相似文献
9.
10.
An early feature of acute pancreatitis is activation of zymogens, such as trypsinogen, within the pancreatic acinar cell. Supraphysiologic concentrations of the hormone cholecystokinin (CCK; 100 nM), or its orthologue cerulein (CER), induce zymogen activation and elevate levels of cAMP in pancreatic acinar cells. The two classes of adenylyl cyclase, trans-membrane (tmAC) and soluble (sAC), are activated by distinct mechanisms, localize to specific subcellular domains, and can produce locally high concentrations of cAMP. We hypothesized that sAC activity might selectively modulate acinar cell zymogen activation. sAC was identified in acinar cells by PCR and immunoblot. It localized to the apical region of the cell under resting conditions and redistributed intracellularly after treatment with supraphysiologic concentrations of cerulein. In cerulein-treated cells, pre-incubation with a trans-membrane adenylyl cyclase inhibitor did not affect zymogen activation or amylase secretion. However, treatment with a sAC inhibitor (KH7), or inhibition of a downstream target of cAMP, protein kinase A (PKA), significantly enhanced secretagogue-stimulated zymogen activation and amylase secretion. Activation of sAC with bicarbonate significantly inhibited secretagogue-stimulated zymogen activation; this response was decreased by inhibition of sAC or PKA. Bicarbonate also enhanced secretagogue-stimulated cAMP accumulation; this effect was inhibited by KH7. Bicarbonate treatment reduced secretagogue-stimulated acinar cell vacuolization, an early marker of pancreatitis. These data suggest that activation of sAC in the pancreatic acinar cell has a protective effect and reduces the pathologic activation of proteases during pancreatitis. 相似文献