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1.
THE high-sulphur proteins of α-keratins, which constitute the non-filamentous matrix between the microfibrils, comprise several major groups of proteins, each group consisting of a number of closely related components. They are obtained in a soluble form by reduction of the disulphide bonds of wool and preferential extraction with alkaline thioglycollate at high ionic strength1. The thiol groups are subsequently stabilized by alkylation with iodoacetic acid. 相似文献
2.
Body size but not colony size increases with altitude in the holarctic ant,Leptothorax acervorum
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ABEL BERNADOU CHRISTINE RÖMERMANN NANA GRATIASHVILI JÜRGEN HEINZE 《Ecological Entomology》2016,41(6):733-736
1. Bergmann's rule states that organisms inhabiting colder environments show an increase in body size or mass in comparison to their conspecifics living in warmer climates. Although originally proposed for homoeothermic vertebrates, this rule was later extended to ectotherms. In social insects, only a few studies have tested this rule and the results were ambiguous. Here, ‘body size’ can be considered at two different levels (the size of the individual workers or the size of the colony). 2. In this study, data from 53 nests collected along altitudinal gradients in the Alps were used to test the hypotheses that the worker body size and colony size of the ant Leptothorax acervorum increase with increasing altitude and therefore follow Bergmann's rule. 3. The results show that the body size of workers but not the colony size increases with altitude. Whether this pattern is driven by starvation resistance or other mechanisms remains to be investigated. 相似文献
3.
Fatih M Simsek Bulent Alten Selim S Caglar Yusuf Ozbel A Murat Aytekin Sinan Kaynas Asli Belen Ozge Erisoz Kasap Mehmet Yaman Samiye Rastgeldi 《Journal of vector ecology》2007,32(2):269-279
The two Old World genera, Phlebotomus and Sergentomyia, were both recorded in southern Anatolia in Turkey. Phlebotomus species predominated and comprised about 93% of the entire collection (3,172 specimens). Out of the sixteen species identified, two belonged to the genus Sergentomyia: S. dentata and S. theodori. The remaining fourteen species in the genus Phlebotomus were grouped under four subgenera including some species that are elsewhere known to act as vectors of human cutaneous leishmaniasis. Most of the Phlebotomus were P. tobbi (32.5%), but P. papatasi, P. transcaucasicus, P. halepensis, P. galilaeus, P. sergenti, P. syriacus, P. neglectus, P. simici, P. alexandri, P. similis, P jacusieli, P. perfiliewi, and P. brevis were also identified. There were two associations of sand fly fauna with altitudinal gradient; the first one at relatively higher altitudes and the second one at lower altitudes. The transition between these two assemblages was within the range of 800-1,000 m. It is likely that Adana and Hatay provinces are transitional areas between western and eastern Anatolia. Mountains do not appear to be important geographical barriers for sand fly distribution. We also found that the proven vector P. sergenti is a widely distributed species throughout southern Anatolia and this species, together with its closely related species P. similis, shows sympatry in Konya Province. 相似文献
4.
Association of Viral Reverse Transcriptase with an Enzyme degrading the RNA Moiety of RNA-DNA Hybrids 总被引:44,自引:0,他引:44
K. MÖLLING D. P. BOLOGNESI H. BAUER W. BÜSEN H. W. PLASSMANN P. HAUSEN 《Nature: New biology》1971,234(51):240-243
DURING replication of RNA tumour viruses, the genetic information contained in the viral RNA seems to be transferred to DNA1,2. Studies on the enzymatic activities present in the virus particles suggest that this transfer is mediated by an RNA dependent DNA polymerase3,4. RNA-DNA hybrids have been demonstrated to occur as intermediates in this reaction5 and single stranded DNA is generated as an early reaction product6, which is then replicated to give a double stranded DNA product6–8. The mechanism by which the single stranded DNA is displaced from the RNA template is, however, not known. 相似文献
5.
Since the exact mechanism of manganese (Mn)-induced learning disability is not known, we investigated the role of elevated
cholesterol in rats exposed daily to 357 and 714 μg Mn/kg for 30 d. Significant Mn accumulation was accompanied by increased
cholesterol content in the hippocampal region of Mn-treated rats. The learning, which is based on the time needed to reach
food placed at the exit of a T-maze after a 1-d training period, was significantly slower in exposed rats than in unexposed
rats. The rats receiving 357 and 714 μg Mn/kg reached the food in 104.5±13.8 and 113.3±25.7 s, respectively, on d 30, whereas
their untreated counterparts reached the food in 28.7±11.4 s. This delay was completely corrected to 29.3±7.8 and 30.7±6.0
s in rats with coadministration of an inhibitor of cholesterol biosynthesis with 357 and 714 μg/kg of Mn. The correction of
impaired learning was associated with the normalization of hippocampal cholesterol, but the Mn level in this region of the
brain was not influenced in rats treated with a drug that inhibits cholesterol biosynthesis. These results suggested that
Mn-induced hypercholesterolemia is involved in Mn-dependent learning disability. 相似文献
6.
ZmHox: a novel class of maize homeobox genes 总被引:2,自引:0,他引:2
Bettina Klinge Bärbel Überlacker Christian Korfhage Wolfgang Werr 《Plant molecular biology》1996,30(3):439-453
7.
Ülo Niinemets 《Ecological Research》1996,11(3):269-281
Dependencies of foliage arrangement and structure on relative irradiance and total height (TH) were studied in saplings ofAcer platanoides andQuercus robur. The distribution of relative foliar area and dry weight (leaf area and weight in a crown layer per total tree leaf area
and weight, respectively) were examined with respect to relative height (RH, height in the crown per TH) and characterized
by the Weibull function. The distributions of relative area and weight were nearly identical, and the differences between
them were attributable to a systematic decline in leaf dry weight per area with increasing crown depth. Foliage distribution
was similarly altered by tree size in both species; RH at foliage maximum was lower and relative canopy size (RCS, length
of live crown per TH) greater in taller trees. However, the distribution was more uniform inA. platanoides than inQ. robur. Apart from the size effects, relative irradiance also influenced canopy structure; RCS increased inQ. platanoides and decreased inQ. robur with increasing irradiance. As crown architecture was modified by irradiance, foliage distribution was shifted upwards with
decreasing irradiance inA. platanoides, but it was independent of irradiance inQ. robur. Higher foliage maximum at lower irradiance in more shade-tolerantA. platanoides is likely to contribute towards more efficient foliar display for light interception and increase the competitive ability
of this species in light-limited environments. Consequently, these differences in crown architecture and foliage distribution
may partly explain the superior behavior ofA. platanoides in understory. 相似文献
8.
Hasan Aydin Süleyman Akocak Nebih Lolak Önder Yumrutaş Uğur Uslu Ibrahim Bozgeyik Fatih Üçkardeş Selami Günal Onur Ceylan 《Journal of biochemical and molecular toxicology》2023,37(8):e23375
Schiff bases (imines or azomethines) are versatile ligands synthesized from the condensation of amino compounds with active carbonyl groups and used for many pharmaceutical and medicinal applications. In our study, we aimed to determine the cytotoxic, antifungal and larvicidal activities of biologically potent bis-sulfonamide Schiff base derivatives that were re-synthesized by us. For this aim, 16 compounds were re-synthesized and tested for their cytotoxic, antifungal and larvicidal properties. Among this series, compounds A1B2 , A1B4 , A4B2 , A4B3 , and A4B4 were shown to have cytotoxic activity against tested cancer lung cell line (A549). The most potent antifungal activity was observed in compounds A2B1 and A2B2 against all fungi. A1B1 showed the strongest larvicidal effect at all concentrations at the 72nd h (100% mortality). These obtained results demonstrate that these type of bis-substituted compounds might be used as biologically potent pharmacophores against different types of diseases. 相似文献
9.
Prof. Dr. Mehmet Emin Duru Büşra Eroğlu Assoc. Prof. Dr. Gülsen Tel-Çayan Meltem Taş-Küçükaydın Dr. Selçuk Küçükaydın Dr. Fatih Çayan Prof. Dr. Özgür Ceylan 《化学与生物多样性》2023,20(6):e202300486
Sunflower honey (SH) is bright yellow, fragrant, pollen-flavoured, slightly herbaceous and has a unique taste. The present research aims to examine the enzyme inhibitory, antioxidant, anti-inflammatory, antimicrobial and anti-quorum sensing activities and phenolic compositions of 30 sunflower honeys (SHs) produced from several regions of Turkey with chemometric study. SAH from Samsun exhibited the best antioxidant activity in β-carotene linoleic acid (IC50: 7.33±0.17 mg/mL) and CUPRAC (A0.50: 4.94±0.13 mg/mL) assays, anti-urease activity (60.63±0.87 %) and anti-inflammatory activity against COX-1 (73.94±1.08 %) and COX-2 (44.96±0.85 %). SHs exhibited mild antimicrobial activity against the test microorganisms while they showed high quorum sensing inhibition zones measured in the range of 42–52 mm against the CV026 strain. The phenolic composition was determined by high performance liquid chromatography with diode array detection (HPLC-DAD) system and levulinic, gallic, p-hydroxybenzoic, vanillic and p-coumaric acids were identified in all studied SHs. The classification of SHs was performed the using PCA and HCA. This study revealed that phenolic compounds and biological properties are effective in classification of SHs according to their geographical origin. The results suggest that studied SHs could be valued as potential agents with versatile bioactivities in oxidative stress-related disease, microbial infections, inflammation, melanoma, and peptic ulcer. 相似文献
10.
Ülo Niinemets 《Trees - Structure and Function》1997,11(7):420-431
The relationship between stand biomass production, and tree age and size is generally a curve with a maximum. To understand
why wood production decreases in the final stages of stand development, the influence of increasing tree size on foliage chemical
composition and substrate requirement for foliage construction in terms of glucose [CC, g glucose (g dry mass) –
1] was investigated in the evergreen conifer Picea abies (L.) Karst. Because it was already known that irradiance affects both foliage morphology and chemistry in this species, and
it was expected that the foliage in large overstory trees would intercept on average more light than that in saplings in understory,
irradiance was measured in the sampling locations and included in the statistical models. CC of needles increased with increasing
total tree height (TH) and was independent of relative irradiance. A major reason for increasing CC with increasing TH was
a greater proportion of carbon-rich lignin in the needles in large trees. However, lignin did not fully account for the observed
changes in CC, and it was necessary to assume that certain other carbon-rich secondary metabolites such as terpenes also accumulate
in the foliage of large trees. Enhanced requirements for needle mechanical strength as evidenced by greater lignin concentrations
in large trees were attributed to increased water limitations with increasing tree height. Because water relations may also
control the sink capacities for assimilate usage, apart from the mechanical requirements, they may provide an explanation
for the accumulation of other energetically expensive compounds in the needles as well. Biomass partitioning within the shoot
was another foliar parameter modified in response to increasing tree size. The proportion of shoot axes, which serve to provide
needles with mechanical support and to supply them with water, decreased with increasing TH. This may limit water availability
in the needles, and/or manifest a lower water requirement of the needles containing proportionally more supporting and storage
substances, and consequently, less physiologically active compounds such as proteins. Probably the same factors which caused
CC of the needles to depend on TH, were also responsible for greater CC of the shoot axes in larger trees. These results collectively
suggest that increasingly more adverse water relations with increasing tree size may provide a mechanistic explanation for
the decline in foliar biomass and its functional activity during stand ageing.
Received: 9 April 1996 / Accepted: 14 January 1997 相似文献