首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Lizards commonly climb in complex three-dimensional habitats, and gekkotans are particularly adept at doing this by using an intricate adhesive system involving setae on the ventral surface of their digits. However, it is not clear whether geckos always deploy their adhesive system, given that doing so may result in decreased (i.e. reduction in speed) locomotor performance. Here, we investigate circumstances under which the adhesive apparatus of clinging geckos becomes operative, and examine the potential trade-offs between speed and clinging. We quantify locomotor kinematics of a gecko with adhesive capabilities (Tarentola mauritanica) and one without (Eublepharis macularius). Whereas, somewhat unusually, E. macularius did not suffer a decrease in locomotor performance with an increase in incline, T. mauritanica exhibited a significant decrease in speed between the level and a 10° incline. We demonstrate that this results from the combined influence of slope and the deployment of the adhesive system. All individuals kept their digits hyperextended on the level, but three of the six individuals deployed their adhesive system on the 10° incline, and they exhibited the greatest decrease in velocity. The deployment of the adhesive system was dependent on incline, not surface texture (600 grit sandpaper and Plexiglas), despite slippage occurring on the level Plexiglas substrate. Our results highlight the type of sensory feedback (gravity) necessary for deployment of the adhesive system, and the trade-offs associated with adhesion.  相似文献   

2.
We used the frog‐eyed sand gecko (Teratoscincus scincus) as a model system to evaluate the locomotor costs of tail loss, and to examine whether tailless geckos use alternative anti‐predator behavior to compensate for the costs of tail loss. Of the 16 field‐captured geckos, eight were used as experimental animals and the remaining ones as controls. Locomotor performance, activity level and anti‐predator behavior were measured for experimental geckos before and after the tail‐removing treatment. Control geckos never undergoing the tail‐removing manipulation were measured to serve as controls for the measurements taken at the same time for experimental geckos. Experimental geckos did not differ from controls in activity level before they underwent the tail‐removing manipulation, but became less active thereafter. The mean locomotor stamina of tailless geckos was reduced by about 30% of the mean value for tailed ones. However, as the maximum stamina predicted from the laboratory trials is seldom required in nature, we expect that the costs associated with the reduced locomotor stamina may be relatively minor in T. scincus. All other examined locomotor (overall speed, maximal speed and stride length) and behavioral (distance to refuge, approach distance and flight distance) traits were not affected by the tail‐removing manipulation. Overall, our results suggest that tail autotomy plays no important role in influencing locomotor performance and anti‐predator behavior in lizards where the tail has no direct role in locomotion but is used to direct predatory strikes away from the torso.  相似文献   

3.

Objective

Aim of this study was to evaluate a new histidine-tryptophan-ketoglutarate (HTK)-based preservation solution on chronic isograft injury in comparison to traditional HTK solution.

Methods

Hearts of C57BL/6J (H-2b) mice were stored for 15 h in 0–4 °C cold preservation solution and then transplanted heterotopically into C57BL/6J (H-2b) mice. Three groups were evaluated: HTK, the base solution of a new preservation solution and hearts without cold ischemia (control). Time to restoration of heartbeat was measured (re-beating time). Strength of the heartbeat was palpated daily and scored on a 4-level scale (palpation score). Animals were sacrificed after 60 days of observation (24 h for TGF-β expression). The transplanted hearts were evaluated histologically for myocardial damage, vasculopathy and interstitial fibrosis. TGF-β expression was assessed immunohistologically. All investigators were blinded to the groups. ANOVA and LSD post hoc test were used for statistical analysis.

Results

The re-beating time was significantly shorter in hearts stored in the new solution (10.3 ± 2.6 min vs. HTK 14.2 ± 4.1 min; p < 0.05). The palpation score was significantly higher in hearts stored in the new solution (2.3 ± 0.4 vs. HTK 1.6 ± 0.5; p < 0.01). Hearts stored in the new solution showed a lower myocardial injury score (1.8 ± 0.2 vs. HTK 2.2 ± 0.7), less interstitial fibrosis (4.8 ± 1.9% vs. HTK 8.5 ± 3.8%, p < 0.05), less vasculopathy (14.7 ± 6.9% vs. 22.0 ± 23.2%; p = 0.06) and lower TGF-β1-expression (6.6 ± 1.4% vs. HTK 12.0 ± 4.6%).

Conclusion

The new HTK-based solution reduces the chronic isograft injury. This protective effect is likely achieved through several modifications and supplements into the new solution like N-acetyl-l-histidine, glycine, alanine, arginine and sucrose.  相似文献   

4.
Polyporus brumalis (strain ibrc05015) secreted high amounts of laccases (Lacs) in liquid medium. With 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as a substrate, Lac activity was 7.72 U ml−1 and this strain secreted a maximum 0.23 mg ml−1 of total protein. The enzyme, PbLac1 was purified to homogeneity using hydrophobic and anion-exchange chromatography. The purified PbLac1 had a molecular mass of 63.4 kDa as determined by polyacrylamide-gel electrophoresis. PbLac1 oxidized a wide range of substrates such as 3,4-dihydroxy l-phenylalanine (l-DOPA) and catechol, but not tysorine. The activity of PbLac1 was increased by addition of 10.0 mM Cu2+. PbLac1 could decolorize several industrial dyes, such as Remazol Brilliant Blue R known as model dyes of environmental xenobiotics. In addition, PbLac1 decolorized a wide range of substrates, such as the carcinogen, Poly R-478, in the presence of violuric acid as mediator. The E° value of PbLac1 was 0.80 V ± 0.01 versus normal hydrogen electrode, which is a very high redox potential compared to those of other basidiomycetous Lacs. These results suggest the potential utility of PbLac1 for industrial applications.  相似文献   

5.
Silver pomfret (Pampus argenteus) is an important fisheries resource in China, but harvest management lacks identification of management units (genetic stocks or populations). Using amplified fragment length polymorphism (AFLP), we investigated the population genetic structure of silver pomfret from the Yellow and East China Seas. In 143 individuals examined from six locations (three locations in the Yellow Sea, three in the East China Sea), a total of 194 loci were detected by six primer combinations. In all loci, 149 loci (76.8%) were polymorphic, and the percentage of polymorphic loci varied within samples from 62.9% to 67.0%. Among the six samples, Nei’s genetic diversity was 0.23 ± 0.20–0.25 ± 0.21, and Shannon’s index was 0.34 ± 0.28–0.36 ± 0.29. Analyses revealed significant genetic differentiation among the six samples, indicating at least six separate populations of silver pomfret in the Southern Yellow and East China Seas.  相似文献   

6.
The black-spotted tokay gecko and red-spotted tokay gecko have different distribution areas and are significantly different in appearance but are classified into the same species Gekko gecko. Twelve microsatellite loci were isolated, characterized and evaluated from wild black-spotted tokay geckos for the first time. Of them, nine loci were successfully amplified in red-spotted tokay geckos using multiplex polymerase chain reactions (PCRs). A total of 208 different alleles were observed in the 70 wild black-spotted and red-spotted tokays, and the average number of alleles per locus was 17.3. The average values for observed heterozygosity, expected heterozygosity and polymorphism information content were 0.762, 0.891 and 0.871, respectively, which showed that the wild G. gecko population had a high level of genetic variability. Both black-spotted tokays and red-spotted tokays showed a significant (P < 0.001) deficit of heterozygotes. The red-spotted tokay (HE = 0.881, A = 16.4) had a higher level of genetic variability than black-spotted tokay (HE = 0.804, A = 10.7). The pairwise FST (P < 0.001) estimates of the two types of tokay were 0.143, which indicated that there was a significant level of genetic differentiation between the two.  相似文献   

7.
The egg tooth of squamates evolved to facilitate hatching from mineralized eggshells. Squamate reptiles can assist their hatching with a single unpaired egg tooth (unidentates) or double egg teeth (geckos and dibamids). Egg tooth ontogeny in two gekkotan species, the leopard gecko Eublepharis macularius and the mourning gecko Lepidodactylus lugubris, was compared using microtomography, scanning electron microscopy, and light microscopy. Investigated species are characterized by different hardnesses of their eggshells. Leopard geckos eggs have a relatively soft and flexible parchment (leathery) shell, while eggshells of mourning geckos are hard and rigid. Embryos of both species, like other Gekkota, have double egg teeth, but the morphology of these structures differs between the investigated species. These differences in shape, localization, and spatial orientation were present from the earliest stages of embryonic development. In mourning gecko, anlagen of differentiating egg teeth change their position on the palate during embryonic development. Initially they are separated by condensed mesenchyme, but later in development, their enamel organs are connected. In leopard geckos, the localization of egg tooth germs does not change, but their spatial orientation does. Egg teeth of this species shift from inward to outward orientation. This is likely related to differences in structure and mechanical properties of eggshells in the studied species. In investigated species, two hatching mechanisms are possible during emergence of young individuals. We speculate that mourning geckos break the eggshell through puncturing action with egg teeth, similar to the pipping phase of chick and turtles embryos. Egg teeth of leopard geckos cut egg membranes similarly to most squamates. Our results also revealed differences in egg tooth implantation between Gekkota and Unidentata: gekkotan egg teeth are subthecodont (in shallow sockets), while those in unidentates are acrodont (attached to the top of the alveolar ridge). © 2020 Wiley Periodicals LLC  相似文献   

8.
Ceratopteris pteridoides (Hook.) Hieron. is an endangered aquatic homosporous fern in China. Genetic diversity and structure of eight populations collected from the mid-lower reaches of Yangtze River were investigated using amplified fragment length polymorphisms (AFLPs). A low level of gene diversity was found at the population level (Pp = 17.4%, HE = 0.039 and I = 0.063), which possibly resulted from its high degree of inbreeding, clonal growth and short life history of this species. C. pteridoides contained high clonal diversity (PD = 0.757, D = 0.992). High population differentiation was revealed by partitioning of genetic diversity (GST = 0.707), and the AMOVA analysis consistently showed that 72.3% of the total genetic diversity was attributable to among-population diversity. Based on the genetic information from UPGMA cluster and principal coordinate analysis, two management units have been identified, and translocation within each management unit is recommended.  相似文献   

9.
Patterns of plant visitation by nectar-feeding lizards   总被引:1,自引:0,他引:1  
Douglas A. Eifler 《Oecologia》1995,101(2):228-233
Geckos in the genus Hoplodactylus visit flowers to feed on nectar. I examined the patterns of flower visitation exhibited by two gecko species (H. maculatus and H. duvauceli) having access to two plant species: pohutukawa (Metrosideros excelsa: Myrtaceae) and flax (Phormium tenax: Agavaceae). Individual geckos were not observed to visit both plant species; individuals visiting flax tended to revisit the same plant. Geckos visiting pohutukawa were larger than those visiting flax and exhibited an early night peak in plant visitation, while lizards on flax displayed a more even pattern of activity throughout the night. On flax, geckos were more likely to be found on plants with a greater number of male flowers. Male flax flowers were of greater diameter than female flowers and produced nectar at higher rates and with greater concentrations of sugars. Experimental manipulation of pohutukawa nectar volumes suggested that the distribution of geckos is influenced by the pattern of nectar availability.  相似文献   

10.
The aim of the present study was to obtain a basic knowledge of the hematology in order to determine changes in blood parameters of the spotted rose snapper Lutjanus guttatus. The morphological features of blood cells were described according to the observations made by light microscopy of Wright-Giemsa-stained blood films. The reference intervals and the mean value were determined for each hematological parameter evaluated in healthy fish and data were compared to those of naturally infected, with dactylogyrid monogeneans fish.Infected fish showed a prevalence of 100% and a mean intensity of 246.6 parasites per fish. Mean values of HCT, WBC, thrombocytes percentage and eosinophils percentage were significantly higher (P < 0.05) in the infected fish. In addition, lymphocytes percentage and total protein were significantly lower (P < 0.05) in the infected fish compared to healthy fish. Only total WBC count, lymphocytes percentage and eosinophils percentage in infected fish were outside reference interval. The hematology of the spotted rose snapper of this study might serve as a basis for future studies and diagnosis. Changes observed in blood parameters in infected fish suggest that the immune system of L. guttatus was affected by the presence of the parasites.  相似文献   

11.
The Socotra Giant Gecko, Haemodracon riebeckii, is the largest species of lizard on Socotra Island. The nocturnal, arboreal and rupiculous living geckos are omnivorous. Two pairs were kept in terrariums and were fed with various insects (crickets, locusts, cockroaches), sweet fruits and other feeding stuff (such as meat, fish). Temporarily H. riebeckii was kept together with other lizards (Eublepharis macularius, Trachylepis socotrana), without any signs of aggressive behaviour. Juveniles and adults of both sexes are able to produce a sound. These acoustic signals seem to be related to predators, because never any intraspecific function could be observed. Within seven years of captive breeding two females produced 253 eggs. Usually two white and sticky soft-shelled eggs were laid within one clutch, more rarely a single egg was laid. The two eggs of a clutch were always laid on the same day. H. riebeckii belongs to the geckos that bury their eggs and practice some brood care, but no special parental care. The female is able to proof with her hind legs the deep and shape of a hollow in the substrate to bury the eggs, which were buried in a sticky and soft-shelled condition. They are oval in shape (egg length 16.4-19.8 mm, egg width 12.4-17.8 mm, quotient EL:EW 1.22±0.05) and have in the beginning a weight ranging from 1.7100 to 2.5201 g. As typical for geckos with hard-shelled eggs the egg weight decreases during the incubation period. The loss can be between 5.59 to 30.29%. The development of eggs up to hatching of young depends upon temperature and the germinal stage in the laid egg. The time difference between the hatching of the young within one clutch of two eggs was usually 1 to 5 days. In some cases there were, however, longer differences (up to 61 days), which are probably caused by different developmental stages of the embryos during the time of egg laying. The shortest incubation period recorded during our investigations was 83 days for eggs incubated at constant temperature of 28 to 29.5 °C and the longest 359 days at 26 to 26.5 °C. Constant high incubation temperatures caused a premature hatching of young. In normal hatched young were the yolk sac retracted and the navel closed. In premature hatched young were the yolk not resorbed and the mortality within the first three month comparatively high. The snout-vent length (SVL) of newly hatched young is from 27 to 39 mm and the tail length (TL) from 25 to 38 mm (SVL:TL index 0.90-1.27), the weight is from 0.7688 to 1.5366 g. Young specimens are distinguished from adults by the brown/white striped lower jaw and the white-banded tail. Young which hatched in the terrarium were eaten by the adults. A loss of young can be avoided if they are raised individually.  相似文献   

12.
Two isolates, designated PRQ-67T and PRQ-68, with an optimum growth temperature of about 50 °C, growth range in medium containing between 1 and 9% NaCl and an optimum pH for growth between 7.5 and 8.0, were recovered from a shallow marine hot spring on a beach, Praia do Fogo, at Ribeira Quente, on the Island of São Miguel in the Azores. Comparisons of 16S rRNA gene sequences show these strains to be most closely related (93.1–94.7% similarity) to species of the genus Amaricoccus, within the family Rhodobacteraceae. Strains are non-pigmented and form non-motile pleomorphic cells that stain Gram-negative, are aerobic, oxidase and catalase positive. The major fatty acids are C18:1ω7c and C18:1ω7c 11-methyl. Ubiquinone 10 is the major respiratory quinone. Major polar lipids are phosphatidylcholine, phosphatidylglycerol and one aminolipid. Based on 16S rRNA gene sequence analysis, physiological and biochemical characteristics we describe a new species of a novel genus represented by strain PRQ-67T (=DSM 22673T = LMG 25334T) for which we propose the name Oceanicella actignis.  相似文献   

13.
I studied the positional behavior and habitat use of Cercopithecus petaurista, the lesser spot-nosed monkey, in the Ivory Coast's Taï Forest for 15 months. I compare these data with similar information collected on sympatric groups of Cercopithecus diana and C. campbelli in order to examine further the relationships between locomotion, posture, support use, stratal use, body size, diet, activity patterns and foraging behavior. Spot-nosed monkeys are predominantly quadrupedal primates that frequent the top layer of the understory during all maintenance activities. Locomotion is characteristically slow and cautious; travel takes place on branches and boughs while foraging occurs on twigs and branches. Postural behavior of Cercopithecus petaurista reflects their reliance on more ubiquitously distributed, less mobile food items. The relationship between body size, climbing, leaping and support use among Taï guenons is weak; interspecific differences are more likely functions of strata use and overall behavioral characteristics, e.g. crypticity. I also compare the locomotion and support use of Cercopithecus petaurista with that of C. ascanius from Uganda's Kibale Forest (Gebo and Chapman, 1995a) in order to assess the behavioral similarity of members of the same superspecies. Although overall support use is quite similar, the monkeys differ significantly in frequencies of quadrupedism, leaping and climbing. I present possible reasons for and implications of these differences.  相似文献   

14.
We found that the androgenic gland (AG) of Macrobrachium rosenbergii possesses three cell types. Type I cells are small polygonal shaped-cells (13.4 μm in diameter), stain strongly with hematoxylin-eosin (H&;E), have abundant multilayered rough endoplasmic reticulum (rER), and nuclei containing mostly heterochromatin. Type II cells are slightly larger (18.6 μm in diameter), stain lightly with H&;E, have rER with dilated cisternae, and nuclei containing mostly euchromatin. Type III cells (previously undescribed) are similar in size and shape to type I cells, but the cytoplasm is unstained and they have a high amount of smooth endoplasmic reticulum (sER) and mitochondria with tubular cristae. Bilateral eyestalk-ablation resulted in AG hypertrophy with a proliferation and predominance of type I cells as determined by bromodeoxyuridine (BrdU) assays. Expression of insulin-like androgenic gland hormone (Mr-IAG), determined by immunohistochemistry, was weak in type I cells, strong in type II cells of both the intact and eyestalk-ablated, and negative in type III cells. It was also detected in spermatogonia, nurse cells, and epithelium lining of the spermatic duct. The function of Mr-IAG in these tissues is yet to be elucidated but the distribution implies a strong role in male reproduction.  相似文献   

15.
Geckos with subdigital adhesive pads can scale smooth vertical surfaces in defiance of gravity. The deployment of the adhesive system is activated by the musculoskeletal system during active traverses of such surfaces, but adhesion on such substrata can also be achieved by passive means, with the body weight of the gecko applying tensile loading to the adhesive setae, maintaining prolonged, static contact with the surface. To investigate whether passively induced adhesion is employed by geckos holding station on smooth vertical surfaces, we investigated the magnitude of shear force generation for the manus and pes, and the positioning of the limb segments and digits in Chondrodactylus bibronii in freely selected resting postures (head‐up, head‐down and facing laterally to the left and right). Our results indicate that different subsets of digits occupy positions consistent with them being passively loaded in different body orientations. Limb segment and digit orientation are consistent within, and differ between, the resting postures, and relatively few of the 20 digits are positioned to take advantage of gravitationally induced loading in any posture. The pedal digits have greater adhesive potential than the manual ones and, more frequently, capitalize on passive loading than do manual digits. This is especially evident in the commonly adopted head‐down resting posture.  相似文献   

16.
Faam B  Daneshpour MS  Azizi F  Salehi M  Hedayati M 《Gene》2012,498(1):116-119

Introduction

Thyroid peroxidase (TPO) gene variations are one cause of thyroid autoimmune diseases. The aim of this study was to examine the association between the T1936C, T2229C and A2257C polymorphisms of the TPO gene and Anti-TPO level.

Materials and methods

In this case–control study, 188 individuals (86 males and 102 females), aged 20–80 years, were randomly selected from among the Tehran Lipid and Glucose Study (TLGS) population. A2257C and T2229C SNPs were detected with RFLP by use of BsrI and Eco57I as the restriction enzymes respectively, while the T1936C SNP was determined with ARMS-PCR.

Results

In the presence of the C allele of T1936C, Anti-TPO level was significantly increased (CC: 238 ± 43.3, CT: 47.7 ± 15.9, TT: 74.1 ± 11.3 IU/L p = 0.002); however, this association was attenuated after adjustment for sex and age (p = 0.059). No significant difference, before and after adjustment, was found in Anti-TPO level in the presence of T2229C SNP (CC: 129.1 ± 24.5, CT: 43.5 ± 12.6, TT: 126.5 ± 13.8 IU/L p = 0.196). The association between A2257C and Anti-TPO level was only significant after adjustment for potential confounders (p = 0.007). The association between ATC and CTT haplotypes and Anti-TPO level was significant (p = 0.023, 0.021 respectively), the association between CTT and Anti-TPO concentration was also significant after adjustment for sex (p = 0.014).

Conclusion

The results of the present study confirmed the association between TPO gene polymorphisms and Anti-TPO level in the Tehranian population.  相似文献   

17.
Many marine gastropods are sedentary as adults but have planktonic larvae which can potentially be dispersed over large distances. Consequently larval transport is expected to play a prominent role in facilitating gene flow and determining population structure. The spotted babylon (Babylonia areolata) is a dioecious species possessing an approximately two week planktonic larval stage. We analyzed the population structure of the spotted babylon using amplified fragment length polymorphism (AFLP). One hundred and sixteen AFLP loci were analyzed in 63 individuals from three populations and revealed a high level of genetic diversity, with all individuals harboring a unique banding pattern. AMOVA results and an assignment test revealed that population differentiation was present. PCoA, pairwise FST and UPGMA tree all revealed that gene flow might be present only on a small geographic scale (around 160 km), but, over a large distance (around 1000 km), only reduced gene flow occurred. A mantel test indicated a highly significant positive correlation between genetic differentiation and geographical distance.  相似文献   

18.
Geckos employ their adhesive system when moving up an incline, but the directionality of the system may limit function on downhill surfaces. Here, we use a generalist gecko to test whether limb modulation occurs on downhill slopes to allow geckos to take advantage of their adhesive system. We examined three-dimensional limb kinematics for geckos moving up and down a 45° slope. Remarkably, the hind limbs were rotated posteriorly on declines, resulting in digit III of the pes facing a more posterior direction (opposite to the direction of travel). No significant changes in limb orientation were found in any other condition. This pes rotation leads to a dramatic shift in foot function that facilitates the use of the adhesive system as a brake/stabilizer during downhill locomotion and, although this rotation is not unique to geckos, it is significant for the deployment of adhesion. Adhesion is not just advantageous for uphill locomotion but can be employed to help deal with the effects of gravity during downhill locomotion, highlighting the incredible multi-functionality of this key innovation.  相似文献   

19.
Shen JL  Huang YZ  Xu SX  Zheng PH  Yin WJ  Cen J  Gong LZ 《Cryobiology》2012,64(3):167-175

Objective

To evaluate long-term cryopreserved human bone marrow cells (BMCs) as a source of functional mesenchymal stem cells (MSCs).

Methods

Samples of human BMCs that were cryopreserved for 23–25 years (n = 20) were thawed to obtain an initial culture and a primary culture (P0) that was propagated through five passages (P1–P5) to obtain MSCs. Freshly collected human bone marrow samples (n = 20) were used as controls for comparison of efficiency of recovery and growth characteristics of MSCs. P3 cultures were tested for their capacity to differentiate into osteoblasts, adipocytes, and neuronal cells. Appropriate staining, immunohistochemical and biochemical methods were employed to ascertain cell type identities at different stages of culturing.

Results

In the initial culture, the cell adherence rate of the cryopreserved cells was significantly lower than that of controls (19.7% vs. 38.2%, p < 0.05) while the relative rate of recovery of MSCs was only 48.5 ± 8.6% in P0. At the end of P3, fibroblast-like cells accounted for about 95% of cells in both cryopreserved and control groups (p > 0.05). These cells were positive for essential MSC surface molecules (CD90, CD105, CD166, CD44, CD29, CD71, CD73) and negative for haematopoietic and endothelial cell markers (CD45, CD34, HLA-DR). The cell growth and cell cycle patterns were similar for both groups. MSCs at P3 from both groups had similar capacities to differentiate in vitro into osteoblasts, adipocytes, and neuronal cells.

Conclusion

Using the methods described here, long-term (23–25 years) cryopreserved human BMCs can be successfully cultivated to obtain MSCs that have good differentiation capabilities.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号