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1.
M.M. van Katwijk D. C. R. Hermus D.J. de Jong R. M. Asmus V.N. de Jonge 《Helgoland Marine Research》2000,54(2-3):117-128
A conceptual model is proposed, describing potential Zostera marina habitats in the Wadden Sea, based on reported data from laboratory, mesocosm and field studies. Controlling factors in the
model are dynamics, degree of desiccation, turbidity, nutrients and salinity. A distinction has been made between a higher
and a lower zone of potential habitats, each suitable for different morphotypes of Z. marina. The model relates the decline of Z. marina in the Wadden Sea to increased sediment and water dynamics, turbidity, drainage of sediments (resulting in increased degree
of desiccation) and total nutrient loads during the twentieth century. The upper and lower delineation of both the higher
and the lower zone of potential Z. marina habitats appear to be determined by one or a combination of several of these factors. Environmental changes in one of these
factors will therefore influence the borderlines of the zones. The lower zone of Z. marina will be mainly affected by increased turbidity, sediment dynamics, degree of desiccation during low tide and nutrient load.
The higher zone will be affected by increases in water and sediment dynamics, desiccation rates and nutrient loads. Potential
Z. marina habitats are located above approx. –0.80 m mean sea level (when turbidity remains at the same level as in the early 1990s)
in sheltered, undisturbed locations, and preferably where some freshwater influence is present. At locations with a high,
near-marine, salinity, the nutrient load has to be low to allow the growth of Z. marina. The sediment should retain enough water during low tide to keep the plants moist. Our results suggest that the return of
Z. marina beds within a reasonable time-scale will require not only suitable habitat conditions, but also revegetation measures, as
the changes in the environment resulting from the disappearance of Z. marina may impede its recovery, and the natural import of propagules will be unlikely. Furthermore, the lower zone of Z. marina may require a genotype that is no longer found in the Wadden Sea.
Received: 26 April 1999 / Received in revised form: 15 October 1999 / Accepted: 16 October 1999 相似文献
2.
A. A. Kepel' 《Russian Journal of Marine Biology》2000,26(6):450-452
The alga Analipus japonicus (Harv.) Wynne displays a distinct seasonal pattern in its development in Peter the Great Bay (Sea of Japan). In winter and spring, it occurs only in the form of basal crusts, and vertical axes develop in the summer–autumn period. It reproduces mostly asexually from July to November. Algae with unilocular sporangia occur very seldom, only in June and July. 相似文献
3.
《Developmental cell》2021,56(21):2952-2965.e9
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4.
Stability and procured instability characterize two opposing types of swimming, steady and maneuvering, respectively. Fins can be used to manipulate flow to adjust stability during swimming maneuvers either actively using muscle control or passively by structural control. The function of the dorsal fins during turning maneuvering in two shark species with different swimming modes is investigated here using musculoskeletal anatomy and muscle function. White‐spotted bamboo sharks are a benthic species that inhabits complex reef habitats and thus have high requirements for maneuverability. Spiny dogfish occupy a variety of coastal and continental shelf habitats and spend relatively more time cruising in open water. These species differ in dorsal fin morphology and fin position along the body. Bamboo sharks have a larger second dorsal fin area and proportionally more muscle insertion into both dorsal fins. The basal and radial pterygiophores are plate‐like structures in spiny dogfish and are nearly indistinguishable from one another. In contrast, bamboo sharks lack basal pterygiophores, while the radial pterygiophores form two rows of elongated rectangular elements that articulate with one another. The dorsal fin muscles are composed of a large muscle mass that extends over the ceratotrichia overlying the radials in spiny dogfish. However, in bamboo sharks, the muscle mass is divided into multiple distinct muscles that insert onto the ceratotrichia. During turning maneuvers, the dorsal fin muscles are active in both species with no differences in onset between fin sides. Spiny dogfish have longer burst durations on the outer fin side, which is consistent with opposing resistance to the medium. In bamboo sharks, bilateral activation of the dorsal in muscles could also be stiffening the fin throughout the turn. Thus, dogfish sharks passively stiffen the dorsal fin structurally and functionally, while bamboo sharks have more flexible dorsal fins, which result from a steady swimming trade off. J. Morphol. 274:1288–1298, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
5.
《水生昆虫》2012,34(2):45-55
Sea-skaters in the genus Halobates Eschscholtz 1822 include some of the most specialised water striders and are found in tropical and subtropical seas around the world. Even though species of Halobates occur in both the Atlantic Ocean and the Red Sea, no extant sea-skater has been reported from the Mediterranean Sea. A fossil, Halobates ruffoi Andersen et al., 1994, described from Middle–Upper Eocene (45 Ma) Italy indicates that sea skaters were present in this part of the world in the past. Other geological evidence points to dramatic changes in the Mediterranean Sea during the Tertiary and Quaternary that may have led to their later extinction. In this paper we review briefly the distribution, systematics, evolution and ecology of Halobates, and discuss the potential for the Mediterranean to be recolonised following expected environmental changes due to global warming. 相似文献
6.
《Molecular & cellular proteomics : MCP》2022,21(12):100438
Human pancreatic stellate cells (HPSCs) are an essential stromal component and mediators of pancreatic ductal adenocarcinoma (PDAC) progression. Small extracellular vesicles (sEVs) are membrane-enclosed nanoparticles involved in cell-to-cell communications and are released from stromal cells within PDAC. A detailed comparison of sEVs from normal pancreatic stellate cells (HPaStec) and from PDAC-associated stellate cells (HPSCs) remains a gap in our current knowledge regarding stellate cells and PDAC. We hypothesized there would be differences in sEVs secretion and protein expression that might contribute to PDAC biology. To test this hypothesis, we isolated sEVs using ultracentrifugation followed by characterization by electron microscopy and Nanoparticle Tracking Analysis. We report here our initial observations. First, HPSC cells derived from PDAC tumors secrete a higher volume of sEVs when compared to normal pancreatic stellate cells (HPaStec). Although our data revealed that both normal and tumor-derived sEVs demonstrated no significant biological effect on cancer cells, we observed efficient uptake of sEVs by both normal and cancer epithelial cells. Additionally, intact membrane-associated proteins on sEVs were essential for efficient uptake. We then compared sEV proteins isolated from HPSCs and HPaStecs cells using liquid chromatography–tandem mass spectrometry. Most of the 1481 protein groups identified were shared with the exosome database, ExoCarta. Eighty-seven protein groups were differentially expressed (selected by 2-fold difference and adjusted p value ≤0.05) between HPSC and HPaStec sEVs. Of note, HPSC sEVs contained dramatically more CSE1L (chromosome segregation 1–like protein), a described marker of poor prognosis in patients with pancreatic cancer. Based on our results, we have demonstrated unique populations of sEVs originating from stromal cells with PDAC and suggest that these are significant to cancer biology. Further studies should be undertaken to gain a deeper understanding that could drive novel therapy. 相似文献
7.
Marc Mercken Ursula Lübke Marc Vandermeeren Jan Gheuens A. Beate Oestreicher 《Developmental neurobiology》1992,23(3):309-321
The growth-associated protein B-50 also termed GAP-43, F1, pp46, P-57 and neuromodulin is a nervous tissuespecific protein kinase C (PKC) substrate that is considered to play a major role in neurite formation, regeneration, and neuroplasticity. We describe the isolation of seven mouse monoclonal antibodies (Mabs) directed against B-50. The Mabs are produced against the bovine B-50, selected by ELISA for cross-reactivity with its human counterpart, and evaluated on Western blots in comparison with the well-characterized affinity-purified rabbit polyclonal antibodies to rat-B-50. The Western blots show that the Mabs NM1, NM4, and NM6 recognize specifically the B-50 of bovine, human, and rat brain extract and the purified PKC phosphorylated and unphosphorylated rat B-50 isoforms. The Mabs NM2 and NM3 cross-react with bovine B-50 immunoreactive c-kinase substrate (BICKS), a protein sharing a 17 amino acid sequence homology with B-50. Two Mabs are useful for the detection of B-50 immunoreactivity in formalin-fixed human and rat brain tissues. In human specimen of the hippocampus, a characteristic neuropil distribution of B-50 is detected by the Mabs. In human muscle, Mabs reveal B-50 in nerve bundles and in axons at motor end plates. Thus, these Mabs are useful in investigating the function and localization of the B-50 protein. 相似文献
8.
《Developmental cell》2022,57(11):1383-1399.e7
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9.
《Cell calcium》2019
MiR-204 is expressed in vascular smooth muscle cells (VSMC). However, its role in VSMC contraction is not known. We determined if miR-204 controls VSMC contractility and blood pressure through regulation of sarcoplasmic reticulum (SR) calcium (Ca2+) release. Systolic blood pressure (SBP) and vasoreactivity to VSMC contractile agonists (phenylephrine (PE), thromboxane analogue (U46619), endothelin-1 (ET-1), angiotensin-II (Ang II) and norepinephrine (NE) were compared in aortas and mesenteric resistance arteries (MRA) from miR-204−/− mice and wildtype mice (WT). There was no difference in basal systolic blood pressure (SBP) between the two genotypes; however, hypertensive response to Ang II was significantly greater in miR-204−/− mice compared to WT mice. Aortas and MRA of miR-204−/− mice had heightened contractility to all VSMC agonists. In silico algorithms predicted the type 1 Inositol 1, 4, 5-trisphosphate receptor (IP3R1) as a target of miR-204. Aortas and MRA of miR-204−/− mice had higher expression of IP3R1 compared to WT mice. Difference in agonist-induced vasoconstriction between miR-204−/− and WT mice was abolished with pharmacologic inhibition of IP3R1. Furthermore, Ang II-induced aortic IP3R1 was greater in miR-204−/− mice compared to WT mice. In addition, difference in aortic vasoconstriction to VSMC agonists between miR-204−/− and WT mice persisted after Ang II infusion. Inhibition of miR-204 in VSMC in vitro increased IP3R1, and boosted SR Ca2+ release in response to PE, while overexpression of miR-204 downregulated IP3R1. Finally, a sequence-specific nucleotide blocker that targets the miR-204-IP3R1 interaction rescued miR-204-induced downregulation of IP3R1. We conclude that miR-204 controls VSMC contractility and blood pressure through IP3R1-dependent regulation of SR calcium release. 相似文献
10.
L. Jerling 《Plant Ecology》1988,74(2-3):161-170
Population fluctuations ofGlaux maritima, along a transect on a Baltle sea shore meadow, were recorded between 1979 and 1983. A bimodal distribution in numbers along the transect reflects the variation in factors regulating numbers: The two maintenance systems of the species, vegetative propagation and sexual reproduction play different roles. Vegetative propagation is fast and responds quickly to variations in the environment. The seeds germinate in strongly fluctuating temperatures which are triggered by disturbances such as flooding, damaging the vegetation. 相似文献