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341.
Two chiral stationary phases, ph-alpha-CD and ph-gamma-CD, were prepared from mono(6(A)-azido-6(A)-deoxy)perphenylcarbamoylated alpha- and gamma-cyclodextrin immobilized onto silica gel via the Staudinger reaction. The chromatographic characteristics of these two chiral stationary phases were evaluated. The influence of different cyclodextrins (CDs) on the enantioselectivities was also investigated in this study. Compared to ph-gamma-CD, ph-alpha-CD exhibited quite good enantioselectivity toward the analytes with bulky molecular structures. It was found that the formation of inclusion complex might play a quite important role in the chiral recognition not only under reverse phases but also under normal phases. 相似文献
342.
Rasha AH Attia Abeer E Mahmoud Haiam Mohammed Mahmoud Farrag Rania Makboul Mona Embarek Mohamed Zedan Ibraheim 《Memórias do Instituto Oswaldo Cruz》2015,110(8):1035-1041
Trichinellosis is a serious disease with no satisfactory treatment. We aimed to
assess the effect of myrrh (Commiphora molmol) and, for the first
time, thyme (Thymus vulgaris L.) against enteral
and encysted (parenteral) phases of Trichinella spiralis in mice
compared with albendazole, and detect their effect on inducible nitric oxide synthase
(iNOS) expression. Oral administration of 500 mg/kg of myrrh and thyme led to adult
reduction (90.9%, 79.4%), while 1,000 mg/kg led to larvae reduction (79.6%, 71.3%),
respectively. Administration of 50 mg/kg of albendazole resulted in adult and larvae
reduction (94.2%, 90.9%). Positive immunostaining of inflammatory cells infiltrating
intestinal mucosa and submucosa of all treated groups was detected. Myrrh-treated
mice showed the highest iNOS expression followed by albendazole, then thyme. On the
other hand, both myrrh and thyme-treated groups showed stronger iNOS expression of
inflammatory cells infiltrating and surrounding encapsulated T.
spiralis larvae than albendazole treated group. In conclusion, myrrh and
thyme extracts are highly effective against both phases of T.
spiralis and showed strong iNOS expressions, especially myrrh which could
be a promising alternative drug. This experiment provides a basis for further
exploration of this plant by isolation and retesting the active principles of both
extracts against different stages of T. spiralis. 相似文献
343.
Contreras FX Sot J Ruiz-Argüello MB Alonso A Goñi FM 《Chemistry and physics of lipids》2004,130(2):635-134
Bacillus cereus sphingomyelinase activity was assayed on large unilamellar vesicles composed of sphingomyelin (SM)/cholesterol (Ch) mixtures at varying proportions. Natural (egg) SM was used with a gel–fluid transition temperature at ca. 40 °C. When the enzyme was assayed at 37 °C, the activity on pure SM was exceedingly low, but a small increase was observed as soon as some Ch was added, and a large enhancement of activity occurred with Ch proportions above 25 mol%. The data were interpreted in terms of sphingomyelinase activity being higher in the cholesterol-induced liquid-ordered phase than in the gel phase. The abrupt increase in activity above 25 mol% Ch would occur as a result of a change in domain connectivity, when the Ch-rich liquid-ordered domains coalesced. In equimolar SM/Ch mixtures, that were in the liquid-ordered state in a wide range of temperatures, sphingomyelinase activity was virtually constant in the 30–70 °C range. The results demonstrate that at the mammalian and bird physiological temperatures Ch modulates sphingomyelinase activity, and that this can occur precisely because most SM have a gel–fluid transition temperature above the physiological temperature range. In addition, Ch activation of sphingomyelinase and the strong affinity of Ch for SM allow the rapid, localised and self-contained production of the metabolic signal ceramide in specific microdomains (rafts). 相似文献
344.
The Australian species of the genus Trigonopterus Fauvel are revised. Eight previously recognized species are redescribed and 24 additional new species are described: Trigonopterus
allaetus Riedel, sp. n., Trigonopterus
athertonensis Riedel, sp. n., Trigonopterus
australinasutus Riedel, sp. n., Trigonopterus
australis Riedel, sp. n., Trigonopterus
bisignatus Riedel, sp. n., Trigonopterus
bisinuatus Riedel, sp. n., Trigonopterus
boolbunensis Riedel, sp. n., Trigonopterus
cooktownensis Riedel, sp. n., Trigonopterus
daintreensis Riedel, sp. n., Trigonopterus
deplanatus Riedel, sp. n., Trigonopterus
finniganensis Riedel, sp. n., Trigonopterus
fraterculus Riedel, sp. n., Trigonopterus
garradungensis Riedel, sp. n., Trigonopterus
hasenpuschi Riedel, sp. n., Trigonopterus
hartleyensis Riedel, sp. n., Trigonopterus
kurandensis Riedel, sp. n., Trigonopterus
lewisensis Riedel, sp. n., Trigonopterus
montanus Riedel, sp. n., Trigonopterus
monteithi Riedel, sp. n., Trigonopterus
mossmanensis Riedel, sp. n., Trigonopterus
oberprieleri Riedel, sp. n., Trigonopterus
robertsi Riedel, sp. n., Trigonopterus
terraereginae Riedel, sp. n., Trigonopterus
yorkensis Riedel, sp. n.. All new species are authored by the taxonomist-in-charge, Alexander Riedel. Lectotypes are designated for the following names: Idotasia
aequalis Pascoe, Idotasia
albidosparsa Lea, Idotasia
evanida Pascoe, Idotasia
laeta Lea, Idotasia
rostralis Lea, Idotasia
sculptirostris Lea, Idotasia
squamosa Lea. A new combination of the name Idotasia
striatipennis Lea is proposed: Trigonopterus
striatipennis (Lea), comb. n.. A key to the species is provided. Australian Trigonopterus occur in coastal Queensland, narrowly crossing into New South Wales. The southern parts of the range are inhabited by species found on foliage. A rich fauna of 19 edaphic species inhabiting the leaf litter of tropical forests is reported for the first time from the Australian Wet Tropics. 相似文献
345.
Anjali Gupta Danqin Lu Harikrushnan Balasubramanian Zhang Chi Thorsten Wohland 《Journal of lipid research》2022,63(6):100220
The localization of many membrane proteins within cholesterol- and sphingolipid-containing microdomains is essential for proper cell signaling and function. These membrane domains, however, are too small and dynamic to be recorded, even with modern super-resolution techniques. Therefore, the association of membrane proteins with these domains can only be detected with biochemical assays that destroy the integrity of cells require pooling of many cells and take a long time to perform. Here, we present a simple membrane fluidizer–induced clustering approach to identify the phase-preference of membrane-associated molecules in individual live cells within 10–15 min. Experiments in phase-separated bilayers and live cells on molecules with known phase preference show that heptanol hyperfluidizes the membrane and stabilizes phase separation. This results in a transition from nanosized to micronsized clusters of associated molecules allowing their identification using routine microscopy techniques. Membrane fluidizer-induced clustering is an inexpensive and easy to implement method that can be conducted at large-scale and allows easy identification of protein partitioning in live cell membranes. 相似文献
346.
Understanding the mechanisms of gas exchange regulation in insects currently is a hot topic of insect physiology. Endogenous variation of metabolism during pupal development offers a great opportunity to study the regulation of respiratory patterns in insects. Here we show that metabolic rates during pupal development of the tenebrionid beetle Zophobas rugipes reveal a typical U-shaped curve and that, with the exception of 9-day-old pupae, the time between two bursts of CO2 (interburst phase) was the only parameter of cyclic CO2 gas exchange patterns that was adjusted to changing metabolic rates. The volume of CO2 released in a burst was kept constant, suggesting a regulation for accumulation and release of a fixed amount of CO2 throughout pupal development. We detected a variety of discontinuous and cyclic gas exchange patterns, which were not correlated with any periods of pupal development, suggesting a high among individual variability. An occasional occurrence of continuous CO2 release patterns at low metabolic rates was very likely caused by single defective non-occluding spiracles. 相似文献
347.
Four chiral stationary phases (CSPs) derived from N-(3,5-dinitrobenzoyl)tyrosine have been synthesized. They differ by the substituent nature (methyl, ethyl, isopropyl, tert-butyl) of the aliphatic amide function. The enantiorecognition ability of these CSPs was evaluated with 10 racemates. For the majority of them, the stereoselectivity increases with the steric hindrance of the substituent. The chiral selector enantiomeric separation on the resulting CSPs has evidenced a reversal of elution order only for CS 4 on CSP 4 (tert-butyl substituent), suggesting a change in its conformation. 相似文献
348.
The role of fire in governing rainforest–eucalypt forest ecotone dynamics is of theoretical interest and has conservation management implications. Several eucalypt forests in the Wet Tropics of Australia have an endangered status due to extensive conversion to rainforest. Rainforest plants are known to survive occasional low intensity fires in the eucalypt forest ecotone. However, the ability of rainforest plants to survive frequent fires remains untested. The timing of rainforest expansion is also a subject of interest, and is generally considered to be delayed until fire has been absent for several years. We used 14 years of data collected across 13 plots in the Wet Tropics of north‐eastern Australia to test predictions regarding rainforest seedling recruitment and post‐fire regenerative capacity. The 13 plots received different numbers of fires, between zero and five, over the 14‐year study. The recruitment of new rainforest plants in the ecotone was most abundant in the initial year after fire. If this post‐fire pulse of recruitment is left undisturbed, it can facilitate the subsequent germination of additional rainforest species. The removal of grass cover, whether temporarily in the immediate post‐fire environment or once a developing rainforest mid strata shades out grasses, appears crucial to abundant rainforest recruitment. A variety of tropical rainforest species can persist under a frequent fire regime through resprouting. The difference in the mode of resprouting, between ground‐level coppicing rainforest plants and canopy resprouting eucalypt forest trees, is the critical mechanism that causes regular fire to maintain an open structure in eucalypt forests. The inability of rainforest species to maintain their height when fires fully scorch their crowns, temporarily resets the forest's open structure and delays the rainforest's ability to dominate through shading out grasses to transform the ecosystem into a closed forest. 相似文献
349.
A. de Garín P. Figuerola A. Basualdo P. Giavedoni P. Oricchio M. Skansy 《International journal of biometeorology》1997,40(3):178-180
The occurrence of fungal diseases is closely linked to specific atmospheric conditions affecting the life cycle of the fungus.
Popular beliefs as well as scientific knowledge are in agreement on the effect of high temperature and moisture on fungal
epidemics. The presence of a film of water on a plant, during an uninterrupted number of threshold hours is in many cases
a necessary, and sometimes sufficient condition for fungal infection to develop. In this paper, we present a method to estimate
the sequence of hours of wet and dry vegetal surface. Conventional hourly meteorological data are used. The accuracy of this
method has been studied over an ideal sunflower field located in Balcarce (Buenos Aires, Argentina) with promising results.
Received: 1 July 1996 / Revised: 2 December 1996 / Accepted: 17 December 1996 相似文献
350.
Peattie AM 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2009,179(3):231-239
Climbing organisms are constantly challenged to make their way rapidly and reliably across varied and often novel terrain.
A diversity of morphologically and mechanically disparate attachment strategies have evolved across widely distributed phylogenetic
groups to aid legged animals in scaling these surfaces, notable among them some very impressive adhesive pads. Despite the
differences between, for example, the dry fibrillar pads of geckos and the smooth, secretion-aided pads of stick insects,
I hypothesize that they face similar functional demands in their environment. I outline three broad criteria defining dynamic
biological adhesion: reusability, reversibility, and substrate tolerance. Organismal adhesive pads must be able to attach
repeatedly without significant decline in performance, detach easily at will, and adhere strongly to the broadest possible
range of surfaces in their habitat. A survey of the literature suggests that evidence for these general principles can be
found in existing research, but that many gaps remain to be filled. By taking a comparative, integrative approach to biological
dynamic adhesion, rather than focusing on a few model organisms, investigators will continue to discover new and interesting
attachment strategies in natural systems. 相似文献