Genetic differentiation between Carex lasiocarpa and C. Pellita (Cyperaceae) in north america

Carex lasiocarpa and C. pellita (sect. Carex) share a very similar morphology and have overlapping ranges in North America, but are found in different habitats characterized by contrasting soil types and pH. We studied allozyme variation and chromosome numbers to assess genetic differentiation between the two taxa. Both principal components analysis on the allele frequencies from 12 putative enzyme-coding loci and cluster analysis of genetic identities separated 51 sampled populations into two groups that were consistent with recognized structural differences between C. lasiocarpa and C. pellita. Mean within-group genetic identities were 0.95 for C. lasiocarpa and 0.93 for C. pellita; mean between-group genetic identity was 0.81. With the exception of two rare alleles, the alleles of C. pellita were a subset of those found in C. lasiocarpa. Principal components analysis of measurements of structural characters from voucher specimens representing 46 populations also separated the two species with minimal overlap. Meiotic squashes of microsporocytes revealed haploid chromosome numbers of 38 and 38 + 1 for C. lasiocarpa and 41 and 40 + 1 for C. pellita. These data support the continued recognition of the two taxa as distinct species, and suggest that C. pellita may be a daughter species still in the process of divergence from C. lasiocarpa.     

Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.     

Molecular Cloning of a Lobster Gαq Protein Expressed in Neurons of Olfactory Organ and Brain

Abstract: We have isolated from an American lobster ( Homarus americanus ) olfactory organ cDNA library a clone, hGα_q, with >80% identity to mammalian and arthropod Gα_q sequences. In brain and olfactory organ, hGα_q mRNA was expressed predominantly in neurons, including virtually all the neuronal cell body clusters of the brain. Gα_q protein was also expressed broadly, appearing on western blots as a single band of 46 kDa in brain, eyestalk, pereiopod, dactyl, tail muscle, olfactory organ, and aesthetasc hairs. These results suggest that hGα_q plays a role in a wide variety of signal transduction events. Its presence in the olfactory aesthetasc hairs, which are almost pure preparations of the outer dendrites of the olfactory receptor neurons, the expression of a single hGα_q mRNA species (6 kb) in the olfactory organ, and the localization of hGα_q mRNA predominantly in the olfactory receptor neurons of the olfactory organ strongly suggest that one function of hGα_q is to mediate olfactory transduction.     

Aspects of hadrosaurian cranial anatomy

Supraorbital bones in Saurolophus angustirostris are described, and their presence in all hadrosaurs is suggested. Frontal-nasal and premaxillar-nasal fontanellae are distinguished in hadrosaurs; their presence is explained as connected with growth and considered to he responsible for the variability of crest structures. New data indicating the presence of a cartilaginous diverticulum nasi within the circumnarial depression in Saurobphus ongustirostris are presented. A physiological (respiratory and/or thermoregulatory) function of the nasal diverticulum is proposed.     

Group mating among Norway rats II. The social dynamics of copulation: Competition,cooperation, and mate choice

The social interactions within groups of Norway rats (Rattus norvegicus) had a strong impact on the individual pattern of copulation which, in turn, affects sperm precedence and the probability of implantation in this species. Males alternated uninterrupted ejaculatory series, augmenting each others' copulatory investment. Females took turns mating after receiving an intromission, collectively potentiating the males' copulatory behaviour; increasing the number of oestrous females increased the number of intromissions and ejaculations achieved by each male but did not affect the amount of copulation experienced by each female. These turn-taking patterns within each sex provided the opportunity to change partners and permitted the emergence of different sex-typical patterns of copulation. Furthermore, the dominant male contributed more intromissions and tended to give each female more ejaculations than the subordinates did. Dominant males were also more likely to inhibit the subordinates' sperm transport. Females competed among themselves for the opportunity to mate with a male as he approached ejaculation and were likely to protect more of the dominant male's sperm transport than the subordinate male's.     

华西银腊梅挥发油化学成分的研究

用水蒸气蒸馏法提取华西银腊梅挥发油,并用气相色谱-质谱(GC-MS)联用技术对其挥发油的化学成分进行分析,结果共鉴定了其中的39种成分,所鉴定成分含量约占总检出量的87.83%。其化学成分主要为(Z,Z)-9,12-十八碳二烯酸甲酯(9.00%),壬醛(5.83%),二十一烷(5.69%),二十烷(5.08%),辛炔酸(4.50%),2,6,10,15-四甲基十七烷(3.93%),(Z)-6-十八烯酸甲酯(3.65%),3,8-二甲基十一烷(3.52%),1-十六碳炔(3.31%),肉豆蔻酸(2.86%),月桂醛(2.81%),壬酸(2.23%),5,6,7,7α-四氢-4,4,7α三甲基-2(4H)-苯并呋喃酮(2.18%)等。     

Characteristics of foraging in the soft-bottom benthic starfish Luidia clathrata (echinodermata: Asteroidea): prey selectivity,switching behavior,functional responses and movement patterns

Summary Luidia clathrata show a strong preference for the infaunal bivalve Mulinia lateralis in Tampa Bay, Florida. Quantitative and qualitative changes in diet occurred over a 7-month period. Individuals may shift from intraoral macrofaunal feeding to intra- and extraoral detrital feeding during periods of low macrofaunal availability. In the laboratory L. clathrata showed switching behavior, feeding disproportionately on the most abundant of two simulataneously presented food models. This switching mechanism may be related to either contact-chemoreceptive rejection of lowdensity food or enhanced distance-chemoreception of high density food. The use of standardized food models eliminated the possibility that handling time was important in switching behavior. Both fed and starved individuals showed functional responses to changes in prey density. However starved individuals ingested greater numbers of prey and spent more time foraging than did fed individuals. Switching and functional response behaviors may be important in promoting nutritional uptake and in causing density-dependent mortality of prey populations. Movement patterns of L. clathrata are directional in the absence of bivalve prey, but become non-directional once patches of prey are encountered. This allows individuals to remain in areas of high prey density. Luidia clathrata has characteristics of an optimal forager, where energy is maximized per unit feeding time.     

Limitation of seedling growth by potassium and magnesium supply for two ectomycorrhizal tree species of a Central African rain forest and its implication for their recruitment

In the ectomycorrhizal caesalpiniaceous groves of southern Korup National Park, the dominant tree species, Microberlinia bisulcata, displays very poor in situ recruitment compared with its codominant, Tetraberlinia bifoliolata. The reported ex situ experiment tested whether availabilities of soil potassium and magnesium play a role. Seedlings of the two species received applications of K and Mg fertilizer in potted native soil in a local shade house, and their responses in terms of growth and nutrient concentrations were recorded over 2 years. Amended soil concentrations were also determined. Microberlinia responded strongly and positively in its growth to Mg, but less to K; Tetraberlinia responded weakly to both. Added Mg led to strongly increased Mg concentration for Microberlinia while added K changed that concentration only slightly; Tetraberlinia strongly increased its concentration of K with added K, but only somewhat its Mg concentration with added Mg. Additions of Mg and K had small but important antagonistic effects. Microberlinia is Mg‐demanding and apparently Mg‐limited in Korup soil; Tetraberlinia, whilst K‐demanding, appeared not to be K‐limited (for growth). Added K enhanced plant P concentrations of both species. Extra applied Mg may also be alleviating soil aluminum toxicity, and hence improving growth indirectly and especially to the benefit of Microberlinia. Mg appears to be essential for Microberlinia seedling growth and its low soil availability in grove soils at Korup may be an important contributing factor to its poor recruitment. Microberlinia is highly shade‐intolerant and strongly light‐responding, whilst Tetraberlinia is more shade‐tolerant and moderately light‐responding, which affords an interesting contrast with respect to their differing responses to Mg supply. The study revealed novel aspects of functional traits and likely niche‐partitioning among ectomycorrhizal caesalps in African rain forests. Identifying the direct and interacting indirect effects of essential elements on tropical tree seedling growth presents a considerable challenge due the complex nexus of causes involved.     

Effect of seaweed extract application on wine grape yield in Australia

Journal of Applied Phycology - Seaweed extracts are agricultural biostimulants that have been shown to increase the productivity of many crops. The aim of this study was to determine the effect of...     

European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

相似文献