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251.
The small phytoplankton genus Triparma belongs to the class Bolidophyceae and contains two distinct forms: silicified species and naked flagellated species (formerly Bolidomonas). Recent studies showed that four silicified species/strains (Triparma laevis f. inornata, T. laevis f. longispina, T. strigata, and T. aff. verrucosa) belong to a single clade that is paraphyletic, because it also contains an unclassified flagellated strain, and is sister to a flagellated species, T. eleuthera. In this study, we isolated and characterized two new strains of silicified species to test the phylogenetic unity of silicified bolidophytes. The isolates were identified as T. retinervis strains because they possessed fine areolation on the cell wall. 18S rDNA and rbcL phylogenetic analyses demonstrated that T. retinervis formed a new silicified clade that is sister to the flagellated species T. pacifica. This reveals that there are at least two distinct clades including both silicified and flagellated Triparma species.  相似文献   
252.
Seeds express various germination behaviors in response to competitor plants. However, germination behaviors in response to facilitator plants are not yet well understood. Rumex obtusifolius seedlings usually appear on the ground near adult conspecific plants, and their survival rate under the canopy of adult conspecifics is higher than that outside the canopy, indicating that adult R. obtusifolius plants facilitate their seedling establishments. We hypothesized that emergence of R. obtusifolius seedlings is promoted by cues from adult conspecifics, but emergence of heterospecific seedlings is not. To test this, we investigated emergence responses of seedlings of R. obtusifolius and three other species that grow with R. obtusifolius in the presence of R. obtusifolius leaf phytochemicals. Emergence of R. obtusifolius seedlings was promoted by the presence of R. obtusifolius leaves. In contrast, emergence of other species seedlings was not promoted by R. obtusifolius leaves. We conclude that germination of R. obtusifolius seeds is facilitated in the presence of conspecifics, via water-soluble chemical exposure, and that recognizing these chemicals has adaptive value.  相似文献   
253.
Wetlands Ecology and Management - Small valley topology on terraced uplands is a unique groundwater-dependent ecosystem in East Asia. Traditionally, this characteristic valley topology has been...  相似文献   
254.
Iguchi  Akira  Tada  Ipputa  Nagano  Atsushi J.  Yasuda  Nina 《Coral reefs (Online)》2021,40(4):1379-1385
Coral Reefs - Pacific crown-of-thorns starfish (Acanthaster cf. solaris) are known to be widely distributed, and previous studies (showing limited genetic structure) suggest that there are high...  相似文献   
255.
256.
The choice of treatment for primary nephrotic syndrome depends on the pathologic type of the disorder. Renal biopsy is necessary for a definitive diagnosis, but it is burdensome for the patients, and can be avoided if tests could be performed using urine or plasma. In this study, we analyzed 100 urinary proteins, 141 plasma proteins, and 57 urine/plasma ratios in cases of diabetic nephropathy (DN; n = 11), minimal change nephrotic syndrome (MCNS; n = 14), and membranous nephropathy (MN; n = 23). We found that the combination of urinary retinol-binding protein 4 and SH3 domain-binding glutamic acid-rich-like protein 3 could distinguish between MCNS and DN, with an area under the curve (AUC) of 0.9740. On the other hand, a selectivity index (SI) based on serotransferrin and immunoglobulin G, which is often used in clinical practice, distinguished them with an AUC of 0.9091. Similarly, the combination of urinary afamin and complement C3 urine/plasma ratio could distinguish between MN and DN with an AUC of 0.9842, while SI distinguished them with an AUC of 0.8538. Evidently, the candidates identified in this study were superior to the SI method. Thus, the aim was to test these biomarkers for accurate diagnosis and to greatly reduce the burden on patients.  相似文献   
257.
The establishment of symbiotic associations in plants requires calcium oscillations that must be decoded to invoke downstream developmental programs. In animal systems, comparable calcium oscillations are decoded by calmodulin (CaM)–dependent protein kinases, but symbiotic signaling involves a calcium/CaM–dependent protein kinase (CCaMK) that is unique to plants. CCaMK differs from the animal CaM kinases by its dual ability to bind free calcium, via calcium binding EF-hand domains on the protein, or to bind calcium complexed with CaM, via a CaM binding domain. In this study, we dissect this dual regulation of CCaMK by calcium. We find that calcium binding to the EF-hand domains promotes autophosphorylation, which negatively regulates CCaMK by stabilizing the inactive state of the protein. By contrast, calcium-dependent CaM binding overrides the effects of autophosphorylation and activates the protein. The differential calcium binding affinities of the EF-hand domains compared with those of CaM suggest that CCaMK is maintained in the inactive state at basal calcium concentrations and is activated via CaM binding during calcium oscillations. This work provides a model for decoding calcium oscillations that uses differential calcium binding affinities to create a robust molecular switch that is responsive to calcium concentrations associated with both the basal state and with oscillations.  相似文献   
258.
This study examined both socioeconomic and cultural factors in explaining ethnic differences in monitoring, behavioral control, and warmth—part of a series of coordinated studies presented in this special issue. Socioeconomic variables included mother's and father's educational levels, employment status, home ownership, number of siblings in the household, and single parent status. Cultural factors included nationality or ethnicity, immigrant status of child, mother's/father's age of arrival in the United States, mother's/father's English language use with the child, child's native fluency, and cultural values for independence and interdependence. The sample consisted of 591 European American, 123 African American, 1,614 Asian American, and 597 Latino students in the ninth grade. All the ethnic minority groups were higher than European Americans on behavioral control, and Latinos were also higher than European Americans on monitoring. However, European Americans were higher on parental warmth than Asian Americans and African Americans. These ethnic group differences primarily remained even after controlling for the socioeconomic factors. Finally, in analyses looking within the Asian and Latino groups, differences in parenting were found within both groups due to nationality or ethnicity, youth's fluency in the native language, and cultural values of interdependence, although values of independence were also related to the parenting of Asian Americans.  相似文献   
259.
Abstract

2′-Deoxy-2-(p-nitrophenyl)-adenosine (.15) was found to be the most potent mutagen when tested with S. typhimurium TA 98 and TA 100 in the series of compounds, whose activity towards TA 98 is one order of magnitude greater than that of 4-nitroquinoline N-oxide.

In another series of reactions, synthesis of 2-alkynyl-adenosines (18) was achieved through the palladium catalyzed cross-coupling of terminal alkynes with 2-iodoadenosine (17). Compounds bearing the 2-C[dbnd]CCH(R)OH side-chain exhibited potent antiallergic activity in rats. These compounds, however, possessed hypotensive activity accompanied by a decrease in heart rate whereas with a longer alkyl side-chain at the 2-position, compounds showed selective hypotensive activity.  相似文献   
260.
Abstract

Reaction of 2′-deoxy-2′-methylidene-5′-O-trityluridine (1) with diethylamino-sulfur trifluoride (DAST) in CH2Cl2 resulted in the formation of a mixture of (3′R)-2′,3′-dideoxy-3′-fluoro-2′-methylidene derivative 3 and 2′,3′-didehydro-2′,3′-dideoxy-2′-fluoromethyl derivative 4 (3:4 = 1:1.5) in 65% yield. A similar treatment of 1-(2-deoxy-2-methylidene-5-O-trityl-β-D-threo-pentofuranosyl)uracil (19) with DAST in CH2Cl2 afforded (3′S)-2′,3′-dideoxy-3′-fluoro-2′-methylidene derivatives 20 and 4 in 38% and 17% yields respectively. Transformation of the uracil nucleosides 4, 12, and 20 into cytosines followed by deprotection furnished the corresponding cytidine derivatives 29, 18, and 25, respectively. The corresponding thymidine congener 27 was also synthesized in a similar manner. All of the newly synthesized nucleosides were evaluated for their inhibitory activities against HIV and for their antiproliferative activities against L1210 and KB cells.  相似文献   
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