Frontiers in Biology

ISSN 1674-7984

ISSN 1674-7992(Online)

CN 11-5892/Q

   Online First

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, Volume 3 Issue 2

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Effects of macroparasites on the energy allocation of reproducing small mammals
Degen A Allan
Front. Biol.. 2008, 3 (2): 123-130.  
https://doi.org/10.1007/s11515-008-0034-x

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Reproduction, including lactation, is the most costly activity in terms of energy expenditure in female mammals. Consequently, the energy requirements of the reproducing female may not be met at this time, especially if other energy demanding activities are occurring concomitantly. Such activities could be the activation and maintenance of an immune system in response to parasitic infestation. These protective processes are energetically demanding and require trade-off decisions among competing energy demands. In the case of a reproducing mammal, the trade-offs occur mainly between defence against parasites and reproductive costs of the host. In this paper, I discuss the effects of macroparasites on the energy allocation of reproducing small mammals.
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Source-sink landscape theory and its ecological significance
CHEN Liding, FU Bojie, ZHAO Wenwu
Front. Biol.. 2008, 3 (2): 131-136.  
https://doi.org/10.1007/s11515-008-0026-x

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Exploring the relationships between landscape pattern and ecological processes is the key topic of landscape ecology, for which, a large number of indices as well as landscape pattern analysis model were developed. However, one problem faced by landscape ecologists is that it is hard to link the landscape indices with a specific ecological process. Linking landscape pattern and ecological processes has become a challenge for landscape ecologists. “Source” and “sink” are common concepts used in air pollution research, by which the movement direction and pattern of different pollutants in air can be clearly identified. In fact, for any ecological process, the research can be considered as a balance between the source and the sink in space. Thus, the concepts of “source” and “sink” could be implemented to the research of landscape pattern and ecological processes. In this paper, a theory of source-sink landscape was proposed, which include: (1) In the research of landscape pattern and ecological process, all landscape types can be divided into two groups, “source” landscape and “sink” landscape. “Source” landscape contributes positively to the ecological process, while “sink” landscape is unhelpful to the ecological process. (2) Both landscapes are recognized with regard to the specific ecological process. “Source” landscape in a target ecological process may change into a “sink” landscape as in another ecological process. Therefore, the ecological process should be determined before “source” or “sink” landscape were defined. (3) The key point to distinguish “source” landscape from “sink” landscape is to quantify the effect of landscape on ecological process. The positive effect is made by “source” landscape, and the negative effect by “sink” landscape. (4) For the same ecological process, the contribution of “source” landscapes may vary, and it is the same to the “sink” landscapes. It is required to determine the weight of each landscape type on ecological processes. (5) The source-sink principle can be applied to non-point source pollution control, biologic diversity protection, urban heat island effect mitigation, etc. However, the landscape evaluation models need to be calibrated respectively, because different ecological processes correspond with different source-sink landscapes and evaluation models for the different study areas. This theory is helpful to further study landscape pattern and ecological process, and offers a basis for new landscape index design.
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Mapping the transcription repressive domain in the highly conserved human gene
WANG Yuequn, LIU Lian, CAI Zhenyu, LI Yongqing, YUAN Wuzhou, ZHU Chuanbing, DENG Yun, MO Xiaoyang, WU Xiushan
Front. Biol.. 2008, 3 (2): 137-142.  
https://doi.org/10.1007/s11515-008-0038-6

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HNULP1, a new member of the basic helix-loop-helix transcription factors, contains a DUF654 domain in its C-terminus and is highly conserved from Drosophilae, yeast, zebrafish to mouse. The function of this motif, however, is currently unknown. In this research, we fused five deletion fragments of the DUF654 domain to the GAL4 DNA-binding domain and then co-transfected with plasmids L8G5-Luc and VP-16. The analysis of the GAL4 luciferase reporter gene indicated that fragments from 228 to 407 amino acids in the DUF654 domain had a strong transcription repression activity. Therefore, this study lays a solid foundation for research on the mechanism of hnulp1 transcriptional regulation and the function of the DUF654 domain.
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Gene frequency of five genetic characteristics in six nationalities in Southern Guizhou Province, China
ZHANG Xun, YU Yuesheng, CAO Xianming, HE Xuehua
Front. Biol.. 2008, 3 (2): 143-146.  
https://doi.org/10.1007/s11515-008-0021-2

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Five characteristics (hair forms, nasal profile, nostril forms, mongoloid fold and upper eyelid fold) were respectively investigated in six nationalities, including the Buyi, Miao, Shui, Maonan, Dong, and Han nationalities in Southern Guizhou, China. The gene frequencies of five characteristics in the six nationalities were estimated and compared. The results indicated that: (1) for hair forms and nasal profile, the frequency of the dominant gene was lower than that of their recessive gene, but the opposite was true for nostril forms. (2) Among different nationalities, the difference of gene frequency of the mongoloid fold, nasal profile, hair forms and upper eyelid fold was quite significant, which was followed by that of nostril forms.
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Effects of special brain area regional cerebral blood flow abnormal perfusion on learning and memory function and its molecular mechanism in rats
KONG Lingbin, YANG Zhiyin, DING Shouhua, AN Rui
Front. Biol.. 2008, 3 (2): 147-153.  
https://doi.org/10.1007/s11515-008-0033-y

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To study the effect of special brain area regional cerebral blood flow (rCBF) abnormal perfusion on learning and memory function and its molecular mechanism, 64 adult male healthy Sprague-Dawley (SD) rats were randomly divided into two groups, the false operation group (control group) and the operation group (model group). After surgical operation, the operation group undertook bilateral common carotid artery permanent ligation, while the other group did not. Learning and memory function were measured by Y-maze at 4 h, 8 h, 24 h and 3 d after surgical operation, respectively. The rCBF of the right frontal lobe and hippocampus was also detected by the PerifluxPF model laser Doppler flowmetry, and the expressions of c-fos or c-jun or Bcl-2 and Bax were also measured by immune histochemistry S-P method accordingly. Results showed that the rCBF of the right frontal lobe and hippocampus in the operation group was significantly lower than that in the false operation group (P < 0.05). The learning indexes, error number (EN), day of reach standard and total reaction time (TRT) in the operation group, were significantly higher than that in the false operation group (P < 0.05). However, the initiative evasion rate in the operation group was significantly lower than that in the false operation group. The study also found that the rCBF was relatively more, the indexes (EN, the day of reach standard and TRT) relatively fewer, but the initiative evasion rate and the memory keeping rate were relatively more. The positive expression and the average absorbency of Fos and Jun in the operation group were significantly higher than that in the false operation group (P < 0.05). Furthermore, Bax and Bcl-2 positive cells were all increased over time in the operation group, and the expression ratio of Bax/Bcl-2 in the operation group was significantly higher than that in the false operation group (P < 0.01). In conclusion, rCBF decrease can impair the learning and memory function in rats, which may be related to the increase of the expression ratio of c-fos or c-jun or Bcl-2 or Bax in the frontal cortex and hippocampus.
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Predicting siRNA activity based on back-propagation neural network
LI Jianlong, WANG Zhengzhi, WANG Xiaomin
Front. Biol.. 2008, 3 (2): 154-159.  
https://doi.org/10.1007/s11515-008-0032-z

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RNA interference (RNAi) is a phenomenon of gene silence induced by a double-stranded RNA (dsRNA) homologous to a target gene. RNAi can be used to identify the function of genes or to knock down the targeted genes. In RNAi technology, 19 bp double-stranded short interfering RNAs (siRNA) with characteristic 3′ overhangs are usually used. The effects of siRNAs are quite varied due to the different choices in the sites of target mRNA. Moreover, there are many factors influencing siRNA activity and these factors are usually nonlinear. To find the motif features and the effect on siRNA activity, we carried out a feature extraction on some published experimental data and used these features to train a back-propagation neural network (BP NN). Then, we used the trained BP NN to predict siRNA activity.
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Conserved hypothetical BB0462 protein enhances the transcription activity of AV promoter
WANG Xingguo, YIN Jiao, XU Xian
Front. Biol.. 2008, 3 (2): 160-164.  
https://doi.org/10.1007/s11515-008-0024-z

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Borrelia burgdorferi BB0462 ORF encodes an unknown functional protein with 110 amino acids. A BLAST search in protein databases and the secondary structure being predicted by the program JUFO showed that the conserved hypothetical BB0462 protein was similar to the members of the YbaB protein family in both amino acid composition and protein structure. The co-transformation of BB0462 ORF and oppA upstream regulation DNA into E. coli host cells and beta-galactosidase activity assay demonstrated that the BB0462 protein enhanced the transcriptional activity of the oppAV promoter, but does not affect those of oppAI, II, III and IV promoters. Analysis of DNA retardation and competitive repression also confirmed that the BB0462 protein bound to the 409 bp upstream regulation DNA fragment close to the initiation codon of the oppAV gene. All data in our study suggested that the BB0462 protein was involved in the transcriptional regulation of the oppAV gene
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Construction of a recombinant yeast strain converting xylose and glucose to ethanol
TIAN Shen, ZANG Jinxin, PAN Yaping, LIU Jikai, YANG Xiushan, YUAN Zhenhong, YAN Yongjie
Front. Biol.. 2008, 3 (2): 165-169.  
https://doi.org/10.1007/s11515-008-0015-0

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Candida shehatae gene xyl1 and Pichia stipitis gene xyl2, encoding xylose reductase (XR) and xylitol dehydrogenase (XD) respectively, were amplified by PCR. The genes xyl1 and xyl2 were placed under the control of promoter GAL in vector pYES2 to construct the recombinant expression vector pYES2-P12. Subsequently the vector pYES2-P12 was transformed into S. cerevisiae YS58 by LiAc to produce the recombinant yeast YS58-12. The alcoholic ferment indicated that the recombinant yeast YS58-12 could convert xylose to ethanol with the xylose consumption rate of 81.3%.
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Genetic variation of the genus by ISSR markers
ZHANG Li, ZHOU Yonghong, DING Chunbang, YANG Ruiwu, LIU Shigui
Front. Biol.. 2008, 3 (2): 170-175.  
https://doi.org/10.1007/s11515-008-0022-1

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We investigated the genetic variation within 32 accessions distributed to 14 species and one variety by using ISSR (inter-simple sequence repeat) markers. The results showed that genetic variation was relatively higher among the accessions. A total of 593 bands were amplified by 12 ISSR primers, of which 535 bands (90.2%) were polymorphic. Eleven to 80 polymorphic bands were amplified from each prime, with an average of 44.6 bands. The interspecies GS (genetic similarity) value ranged from 0.430 to 0.866, and the average was 0.620. Cluster analysis showed that all accessions could be classified into 4 groups by ISSR markers. The different accessions in a species were clustered together, but they had genetic variation in molecular levels. There was obvious interspecies genetic variation. Species with similar morphological characteristics and from the same areas or neighboring geographical regions were clustered together and had close relationships. ISSR markers are useful in analyzing interspecies variation in Kengyilia.
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Assessment of Hebei flora against the IUCN Red List Criteria in China
PENG Xianjun, ZHAO Jiancheng, LI Lin, SUN Yongzhen, NIU Yulu, GUO Xiaoli
Front. Biol.. 2008, 3 (2): 176-186.  
https://doi.org/10.1007/s11515-008-0029-7

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Some plants of Hebei Province in China are under threat from human activities, such as over-herding and over-exploitation of wild medicinal plants and industrial plants, etc. To identify the plants in danger in the province and to inspect the quality of the environment encompassing Beijing and Tianjin, a red list of the threatened flora of Hebei Province was produced by using the IUCN Red List Criteria (version 3.1) and its guidelines (version 6.2). Some 262 species were assessed and the results were as follows: (1) the threatened flora include 211 species, accounting for 7.95% of the total native vascular plants. Among them, 44 are Critically Endangered, 80 Endangered and 87 Vulnerable; (2) the destruction of the habitat caused by human activities and the actual or potential exploitation of the plants themselves were the main threat factors of Hebei flora; (3) most of the threatened plants are located in the western, northern and northeastern mountainous regions, namely the key regions of Hebei plant diversity; the endemic and regionally endemic species are severely threatened. Consequently, the assessment not only presented the threatened status of Hebei flora but also indicated the relatively fragile health status of the environment of Beijing and Tianjin. Thus, it is suggested that the application of the IUCN Red List Criteria at the regional level, as an index, could reflect the health status of the local ecosystem. In addition, more concrete measures are needed to conserve the plant diversity and the natural ecosystem of Hebei Province and even the whole region encompassing Beijing and Tianjin.
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Seed germinating characteristics of 54 gramineous species in the alpine meadow on the eastern Qinghai-Tibet plateau
Bu Haiyan, Xu Xiuli, Liu Kun, Jia Peng, Wen Shujun, Sun Dashuai, Du Guozhen, Ren Qingji
Front. Biol.. 2008, 3 (2): 187-193.  
https://doi.org/10.1007/s11515-008-0027-9

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The germination experiment was started on March 3, 2004, and seeds were collected from July to October in 2003. We analyzed the percentage of germination, days to first germination, germination period and days to 50% germination. Among the 54 examined species, 26 species exceeded 80% germination, 11 species exceeded 60%–80% germination, 8 exceeded 40%–0%, 5 exceeded 20%–40%, and 4 showed less than 20%. A principal-component analysis revealed that the species were distributed along two statistically independent axes, the first primarily represented the germination rate and the second represented the time of germination process. Based on scores of germination characteristics, cluster analysis of the 54 gramineous species could be divided into 4 distinct groups: rapid, slow, intermediate germinating (germination percentage> 50%), and low germinating (germination percentage< 50%). The meaning of different groups to the vegetation regeneration was discussed.
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Response of reed community to the environment gradient-water depth in the Yellow River Delta, China
CUI Baoshan, ZHAO Xinsheng, YANG Zhifeng, CHEN Bin, TANG Na, TAN Xuejie
Front. Biol.. 2008, 3 (2): 194-202.  
https://doi.org/10.1007/s11515-008-0025-y

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We investigated and monitored a reed community in the fields. Data on the bio-ecological characteristics and beta-diversity of reed communities in different environmental gradients (mainly based on water depth) of the Yellow River Delta were collected through multi-analysis, extremum analysis and beta-diversity index analysis. In accordance with the square sum of deviations (Ward) cluster analysis, 10 sampling plots were divided into six types with the dominant plants in different plots varying according to the change in environmental gradients. The dominant plants in these plots varied from aquatic plants to xerophytes and salt tolerant plants as water depth decreased. The average height and diameter of the reeds at breast level were significantly correlated with the average water depth. The fitness curves of average density and coverage with average water depth were nonlinear. When the average water depth was 0.3 m, the average density and coverage of reeds reached the apex value, while the height and diameter of the reeds at breast level increased with the water depth. There were obvious changes to the environmental gradient in the Yellow River Delta. The transitional communities were also found to exist in the Yellow River Delta by beta-diversity analysis. Vicarious species appeared with the change in water depth. The occurrence of substitute species is determined by the function of common species between adjacent belts. The different functions of common species led to differences in community structure and function and differences in dominant plants. The result reflects the variations of species present in different habitats and directly reflects environmental heterogeneity. The values of beta-diversity indices of adjacent plots were higher than those of nonadjacent plots. There are transition zones between the xerophytes and aquatic plants in the Yellow River Delta. In an aquatic environment, the similarity of reed community is higher than that of xeromorphic plants. The beta-diversity index can reflect plant succession trends caused by the change in environmental gradients in the Yellow River Delta. The beta-diversity index reveals plant responses to changes in environmental gradient and is helpful in observing changes in patterns of species diversity in relation to environmental gradient change and evolving trends in the future, which in turn plays a prominent role when environmental water requirements of wetland are discussed.
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Induction, selection and antibacterial activity of the antibacterial peptides from lepidopteran insect cultured cell lines
PENG Rong, LIU Kaiyu, YAO Hanchao, YANG Hong, HONG Huazhu, YANG Zhong, CUI Yanfang
Front. Biol.. 2008, 3 (2): 203-206.  
https://doi.org/10.1007/s11515-008-0030-1

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We induced 3 cell lines that were in vitro cultured from Lepidoptera with heat inactivated Escherichia coli DH5? to stimulate the antibacterial peptide followed by antibacterial activity assay, induction dynamic research and Tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Tricine SDS-PAGE) experiment. The antibacterial activity of the induced BTI-Tn-5B1 cell line was the highest, and the antibacterial activity increased gradually to the highest level in 16 hours after stimulation. A new antibacterial peptide with a molecular weight of about 8000 Da was preferentially induced in Trichoplusia ni BTI-Tn-5B1 cells in 16 hours after stimulation. Antibacterial activity assays indicated that it had inhibition against Staphylococcus aureus, Escherichia coli K12D31 and Salmonella derby. It has especially strong inhibition against Gram-negative bacteria such as Escherichia coli K12D31 and Salmonella derby.
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Molecular phylogenetic relationship of based on sequences of mtDNA
ZHU Shihua, YANG Yingchun, ZHENG Wenjuan, SHEN Xiquan, ZOU Jixing
Front. Biol.. 2008, 3 (2): 207-212.  
https://doi.org/10.1007/s11515-008-0028-8

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The mtDNA Cyt b gene was sequenced partially for Variola louti of Serranidae, Epinephelinae and seven endemic species of groupers-Epinephelus awoara, E. brunneus, E. coioides, E. longispinis, E. sexfasciatus, E. spilotoceps and E. tauvina in China. The seven endemic species and other seven foreign species of groupers-E. aeneus, E. caninus, E. drummondhayi, E. haifensis, E. labriformis, E. marginatus and E. multinotatus from the GenBank were combined and analysed as ingroup, while Variola louti was used as outgroup. We compared the 420 bp sequences of Cyt b among the 15 species and constructed two types of molecular phylogenetic trees with maximum parsimony method (MP) and neighbor-joining method (NJ) respectively. The results were as follows: (1) As to the base composition of mtDNA Cyt b sequence (402 bp) of 14 species of Epinephelus, the content of (A + T) was 53.6%, higher than that of (G + C) (46.4%). The transition/transversion ratio was 4.78 with no mutation saturation. (2) The cluster relationships between E. awoara and E. sexfasciatus, E. coioides and E. tauvina, E. longispinis and E. spilotoceps were consistent with phenotypes in taxonomy. (3) In the phylogenetic tree, the species in the Atlantic Ocean were associated closely with those in the Pacific Ocean, which suggested that the Cyt b sequences of Epinephelus were highly conserved. This may be attributed to the coordinate evolution. (4) In wel1-bred mating or heredity management, mating Epinephelus of the same branch should be avoided. It is likely to be an effective way to mate the species of the Atlantic Ocean with those of the Pacific Ocean to improve the inheritance species.
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Spatial distribution of (Lepidoptera: Cossidae) pupae in a seabuckthorn () stand
ZONG Shixiang, LUO Youqing, XU Zhichun, WANG Tao, Kari Heliovaara
Front. Biol.. 2008, 3 (2): 213-218.  
https://doi.org/10.1007/s11515-008-0037-7

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The seabuckthorn carpenter moth, Holcocerus hippophaecolus, which has a generation time of four years, is recently becoming one of the major pests of the seabuckthorn (Hippophae rhamnoides) in Inner Mongolia, Liaoning, Shanxi, Ningxia and Shaanxi of China (Hua et al., 1990). The larvae of the H. hippophaecolus mainly damage the stems and roots of the seabuckthorn, and the mature larvae pupate in the soil. The spatial distribution of the pupae was analyzed by using biostatistics and geostatistics in order to effectively control the insect and further study the spatial distribution of the population. Results show that most of the pupae (90%) had an eclosion time span from early June to the end of July. The sex ratio of the pupae was nearly 1:1 in the woodland samples. In addition, 24.3% of the 971 trees investigated had pupae and it ranged from 0 to 4 per tree within a distance of 1.3 m from the base of the stem. 90% of the pupae were aggregated within a distance of 1 m from the base of the stem. The pupae show intense spatial aggregation in the sampled woodland which had an 11.1 m spatial dependence and a 90.7% intensity in the local spatial continuity. Moreover, the population presented an intensive spotted distribution and many aggregated spots were found in the woodlands. As for the relationship between grid size and variogram of the pupae, the variations in the range, the intensity of local spatial continuity and the sill were all very low or non-existent when the grid size was 5 m, 6 m or 7 m. Whereas, the value of the decisive coefficient was the biggest when the grid size was 5 m making it the ideal grid size.
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Diet composition of post-metamorphic bullfrogs () in the Zhoushan archipelago, Zhejiang Province, China
WANG Yanping, WANG Yihua, LU Ping, ZHANG Fang, LI Yiming
Front. Biol.. 2008, 3 (2): 219-226.  
https://doi.org/10.1007/s11515-008-0036-8

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Bullfrogs (Rana catesbeiana) are listed as one of the 100 worst invasive alien species in the world. They are generalist predators and thus may affect native species through predation. In previous studies, the food contents of bullfrogs were mostly examined at a single site. In the present study, the diet composition of post-metamorphic bullfrogs on eight islands (Daishan, Liuheng, Xiushan, Fodu, Taohua, Xiashi, Cezi, and Putuoshan) in the Zhoushan Archipelago, Zhejiang Province of China, were examined by using the stomach flushing method from June 30 to August 11 in 2005. A total of 391 individual frogs were measured, including 113 adults and 278 juveniles. The analysis of the stomach contents shows that, for adult bullfrogs, the most important prey (by diet volume) overall were Decapoda, Coleoptera, Odonata, Mesogastropoda, Raniformes, and Cypriniformes. For juvenile bullfrogs, these were Decapoda, Coleoptera, Cypriniformes, Odonata, Orthoptera, Hymenoptera, Lepidoptera larvae, Mesogastropoda, and Raniformes. Moreover, the prey size and diet volume increased with the body size of both adult and juvenile bullfrogs. The diet composition of primary preys of bullfrogs was significantly different among the islands. The results indicate that bullfrogs exert different predatory influences on native fauna at different sites and that bullfrogs are generalist predators with extensive ecological impacts on native fauna.
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Identification of sympatric bat species by the echolocation calls
SUN Keping, FENG Jiang, LIU Ying, JIN Longru, JIANG Yunlei
Front. Biol.. 2008, 3 (2): 227-231.  
https://doi.org/10.1007/s11515-008-0017-y

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One hundred and thirty-eight echolocation calls of 63 free-flying individuals of five bat species (Rhinolophus ferrumequinum, Myotis formosus, Myotis ikonnikovi, Myotis daubentoni and Murina leucogaster) were recorded (by ultrasonic bat detector (D980)) in Zhi’an village of Jilin Province, China. According to the frequency-time spectra, these calls were categorized into two types: FM/CF (constant frequency) / FM (R. ferrumequinum) and FM (frequency modulated) (M. formosus, M. ikonnikovi, M. daubentoni and M. leucogaster). Sonograms of the calls of R. ferrumequinum could easily be distinguished from those of the other four species. For the calls of the remaining four species, six echolocation call parameters, including starting frequency, ending frequency, peak frequency duration, longest inter-pulse interval and shortest inter-pulse interval, were examined by stepwise discriminant analysis. The results show that 84.1% of calls were correctly classified, which indicates that these parameters of echolocation calls play an important role in identifying bat species. These parameters can be used to test the accuracy of general predictions based on bats’ morphology in the same forest and can provide essential information for assessing patterns of bat habitat use.
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Habitat selection of the Tibetan Snow Cock in the spring in Lhasa
LI Jiaqi, SHI Hongquan, LIU Naifa
Front. Biol.. 2008, 3 (2): 232-235.  
https://doi.org/10.1007/s11515-008-0035-9

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The habitat selection of Tibetan Snow Cocks in shrub vegetation was investigated in Lhasa, Tibet, China, between March and April, 2005. Fourteen parameters were measured. These include altitude, slope, slope aspect, slope position, vegetation cover, plant type and other environmental parameters. Results show that Snow Cocks favor foraging in areas where vegetation cover was small and close to the residents’ houses. Supplementary food supplied by humans has caused Snow Cocks to decrease their foraging range. Snow Cocks also favor roosting in areas with low vegetation, sparse grass, short grass, large rocks and close to houses. The Snow Cocks’ activity in the study areas show a close relationship with human activities.
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Temporal-spatial variation and the influence factors of precipitation in Sichuan Province, China
LIU Ruimin, SHEN Zhenyao
Front. Biol.. 2008, 3 (2): 236-240.  
https://doi.org/10.1007/s11515-008-0031-0

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Precipitation is a key factor in the water cycle. At the same time, precipitation is the focus of study in meteorology and climatology, ecological environmental assessment, non-point source pollution and so on. Understanding the temporal-spatial variation and the corresponding factors of precipitation has become the object of hydrology and environmentology. Based on the annual precipitation data, we analyzed the spatial distribution of precipitation in Sichuan Province in China as well as the temporal-spatial variation and the corresponding influence factors involved. The results show that the amount of precipitation was abundant, but the spatial distribution was not consistent with it and the amount of precipitation gradually declined from the south-east to the north-west in Sichuan Province, China. Moreover, the spatial distribution was different throughout the years. The result of correlation analysis indicated that elevation, temperature and air pressure were three key factors affecting the amount and distribution of precipitation, and the correlation coefficients were -0.56, 0.38 and 0.45 respectively. Notably, the relationship between the slope of topography and precipitation were significantly negative and the average correlation coefficient was -0.28.
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Gill rays of primitive vertebrate from Early Cambrian: a first record
CHEN Ailin, HUANG Diying
Front. Biol.. 2008, 3 (2): 241-244.  
https://doi.org/10.1007/s11515-008-0020-3

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Yunnanozoans (including Yunnanozoon and Haikouella) are important representatives of the primitive vertebrates in the Early Cambrian Chengjiang fauna. For Yunnanozoans, we know less about Yunnanozoon than about Haikouella due to the poor preservation of Yunnanozoon. Up to now, there have been some reports that Haikouella had developed gill rays, while there have been no reports on Yunnanozoon. In this paper, we described our new findings of the distinct gill rays of Yunnanozoon lividum based on new well-preserved material collected from the Lower Cambrian Maotianshan Shale in Xiaolantian of Yunnan Province, China. This study provides new data on the evolutionary relationship of the primitive vertebrates and their early evolution.
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