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1.
Iain Darbyshire 《Kew Bulletin》2008,63(2):261-268
Summary Three new species are described in Barleria L. sect. Stellatohirta M. Balkwill from tropical Africa: B. aristata from south-central Tanzania, B. aenea from south-western Tanzania and northeast Zambia, and B. purpureotincta from south-western Zambia. Their affinities and conservation status are discussed. 相似文献
2.
The distribution of Daphniaspecies in tropical Africa is poorly known and understood. Daphniaare assumed rare in tropical regions, but systematic studies covering large areas are sparse. We sampled the active community
(live zooplankton) and/or the dormant community (diapausing egg banks in the sediment) of 41 standing water bodies in Kenya
in search for Daphnia.Overall the dormant communities yielded 11 species of Daphnia, a species richness more than twice the species richness found in the active communities. Dormant community species diversity
better reflects the spatial, and particularly the temporal (multi-annual) variation in environmental conditions available
to Daphniain these tropical standing waters. Hence, we suggest that the dormant community be taken into account when assessing local
zooplankton diversity, especially in fluctuating tropical lake ecosystems, where the presence of each local Daphniaspecies in the active community may be strongly seasonal or erratic. Geographic distribution data from this study are supplemented
with previous records of Daphniain East Africa to provide an overview of the known distribution of Daphniain Kenya and neighbouring countries. We also present a detailed key for morphological identification of the ephippia of the
11 Daphniaspecies encountered, complemented with photographs and drawings of diagnostic characters. 相似文献
3.
Rhitu Rai Prasanta K. Dash B. M. Prasanna Aqbal Singh 《World journal of microbiology & biotechnology》2007,23(6):853-858
The genotypic diversity of indigenous bacterial endophytes within stem of tropical maize (Zea mays L.) was determined in field and greenhouse experiments. Strains were isolated from stem tissues of a tropical maize cultivar
(PEHM-1) by trituration and surface disinfestation and their population dynamics was determined. Endophytes were found in
most of the growing season at populations ranging from 1.36–6.12 × 105 colony-forming units per gram fresh weight (c.f.u./gm fw) of stem. Analysis of these bacterial endophytes using Gas Chromatography—Fatty
Acid Methyl Ester (GC-FAME) led to the identification of Bacillus pumilus, B. subtilis, Pseudomonas aeruginosa and P. fluorescens as the relatively more predominant group of bacterial species residing in maize stem. When the maize seedlings grown in a
greenhouse were inoculated with these four isolates individually, their population densities decreased (1.6–3.1 × 105 c.f.u./gm fw of stem) as compared to the field-grown maize (1.8–3.8 × 105 c.f.u./gm fw of stem). The highest persistence, however, was recovered in the case of B. subtilis with a population density of 3.1 × 105 c.f.u./gm fw of stem tissue on 28 days after emergence (DAE). This is the first report on population dynamics of bacterial
endophytes from tropical maize and the results establish that symptomless populations of bacteria exist in the maize stem. 相似文献
4.
Erik Eschbach Martin Pfannkuchen Michael Schweikert Denja Drutschmann Franz Brümmer Sergei Fokin Wolfgang Ludwig Hans-Dieter Grtz 《Systematic and applied microbiology》2009,32(7):490-500
An intracellular bacterium was discovered in two isolates of Paramecium sexaurelia from an aquarium with tropical fish in Münster (Germany) and from a pond in the Wilhelma zoological–botanical garden, Stuttgart (Germany). The bacteria were regularly observed in the cytoplasm of the host, but on some occasions they were found in the macronucleus of the host cell. In these cases, only a few, if any, bacteria were observed remaining in the cytoplasm. The bacterium was not infectious to P. sexaurelia or other species of Paramecium and appeared to be an obligate intracellular bacterium, while bacteria-free host cells were completely viable. The fluorescence in situ hybridisation (FISH) and comparative 16SrDNA sequence analyses showed that the bacterium belonged to a new genus, and was most closely, yet quite distantly, related to Holospora obtusa. In spite of this relationship, the new bacteria differed from Holospora by at least two biological features. Whereas all Holospora species reside exclusively in the nuclei of various species of Paramecium and show a life cycle with a morphologically distinct infectious form, for the new bacterium no infectious form and no life cycle have been observed. For the new bacterium, the name Candidatus Paraholospora nucleivisitans is suggested. The host P. sexaurelia is usually known from tropical and subtropical areas and is not a species typically found in Germany and central Europe. Possibly, it had been taken to Germany with fish or plants from tropical or subtropical waters. Candidatus Paraholospora nucleivisitans may therefore be regarded as an intracellular neobacterium for Germany. 相似文献
5.
Yi-T. Lien Y. Nakano S. Plathong H. Fukami Jih-T. Wang C. A. Chen 《Coral reefs (Online)》2007,26(1):35-44
Biogeographic investigations have suggested that coral-symbiont associations can adapt to higher temperatures by hosting a
heat-tolerant Symbiodinium, phylotype D. It is hypothesized that phylotype D is absent in high latitudes due to its heat-tolerant characteristics. In
this study, this hypothesis was tested by examining the symbiont diversity in a scleractinian coral, Oulastrea crispata, throughout its entire latitudinal distribution range in the West Pacific. Molecular phylotyping of the 5′-end of the nuclear
large subunit of ribosomal DNA (lsu rDNA) indicated that phylotype D was the dominant Symbiodinium in O. crispata from the tropical reefs to the marginal non-reefal coral communities. Several colonies of tropical populations were associated
with phylotype C, either alone or simultaneously with phylotype D. Analysis of the polymerase chain reaction products using
single-strand conformation polymorphism (SSCP) detected relatively low densities of phylotype C in most of the O. crispata colonies surveyed. These results provide evidence for the occurrence of phylotype D in cold-water outlying coral communities.
The dominant occurrence of phylotype C in some O. crispata colonies on tropical reefs and the relatively low densities of phylotype C identified by SSCP in subtropical and temperate
populations show that the dominant symbiont type can vary in this coral species and that multiple symbionts can co-occur in
the same host. 相似文献
6.
A study was conducted to ascertain monthly changes in biomass of the plant and nutrient content in various organs of Nymphoides hydrophylla grown in a tropical pond during September 1999–August 2000 in relation to environmental factors. Biomass of N. hydrophylla ranged from 25 to 247 g dry weight m−2. Among the various organs, leaf blade showed highest nitrogen (3.0–4.6%) and phosphorus content (0.9–2.4%). Comparative data
of three Nymphoides species showed that N. peltata, the temperate species, had maximum potential of biomass production while long flowering period, year around growth, higher
nitrogen content in various organs and presence of other associated flora were unique features of tropical species (N. hydrophylla and N. indica). Both water temperature and water level together appeared to be the best environmental variables that significantly explained
the variability in biomass of N. hydrophylla. 相似文献
7.
8.
Biological parameters such as age, growth and age (or size) at maturity are vital for stock assessment and management. Aging
is essential in yielding such information. However, limited aging studies have been conducted for large tropical pelagic species
in the eastern and central tropical Pacific Ocean. The objective of this study is to conduct a length frequency analysis for
estimating growth and mortality of bigeye tuna in the eastern and central tropical Pacific Ocean using samples from the Chinese
longline fishery during February to November 2006. The von Bertalanffy growth parameters of asymptotic fork length L
∞
and growth coefficient k were estimated at L
∞
= 207.4 cm fork length, k = 0.23 year-1, and theoretical age at zero length t
0
= −0.40 year. The total mortality rate (Z) was estimated to be 0.60; the fishing mortality rate (F) and the natural mortality rate (M) were 0.25 year-1 and 0.35 year-1, respectively. The exploitation rate (E) was 0.16. This study provides the estimates of growth and mortality rate for bigeye tuna in the eastern and central tropical
Pacific Ocean, which can be used as biological input parameters in further stock evaluations in this region. However, age
analysis, further validation of the age composition and stock structure are needed for future studies. 相似文献
9.
Two new species of <Emphasis Type="Italic">Neosartorya</Emphasis> from Amazonian soil,Brazil 总被引:1,自引:0,他引:1
Neosartorya indohii and N. tsurutae, two new Neosartorya species isolated from tropical rainforest soil in the Amazonian area, Brazil, are described and illustrated. Neosartorya indohii is characterized by its spreading growth on Czapeks and malt extract agars, light yellow cleistothecia, broadly lenticular ascospores with two conspicuously serrate-incised equatorial crests and tuberculate convex surfaces, and globose to subglobose conidia with a smooth wall. Neosartorya tsurutae is characterized by its spreading growth on Czapeks and malt extract agars, white cleistothecia, broadly lenticular ascospores with four equatorial crests and rugulose-ruminate convex surfaces, and ovoid to broadly ellipsoidal conidia with a smooth wall. 相似文献
10.
Ryosuke Tamura Yasuyuki Hashidoko Noriko Ogita Suwido H. Limin Satoshi Tahara 《Ecological Research》2008,23(3):573-579
Hawaii yellow-eyed grass (Xyris complanata: Xyridaceae) inhabits infertile, acidic peat soil in the rainy tropical zone in Southeast Asia. This monocot plant produces
a large number of dormant seeds in order to make a large deposit to seed bank in the soil. Under laboratory conditions, surface-sterilized
X. complanata seeds are rarely able to germinate on sterilized peat moss bed; they require inoculation with either seed epiphytic or soil
fungi to facilitate active seed germination. In the present study, three different genera of seed epiphytic fungi were isolated,
and two common fungal genera, Fusarium sp. (strain R-1) and Penicillium sp. (strain Y-1), were found to promote seed germination of X. complanata. In sterile peat moss beds, the germination-stimulating fungi also showed growth-promoting effects on X. complanata seedlings. These results suggest that the seed germination-promoting fungi likely function as genuine partners for X. complanata in tropical open peat lands. 相似文献
11.
The biological, physical and chemical properties of Lake Elphinstone were studied during a dense, toxic cyanoprokaryote bloom dominated by Microcystis. Decreases in total abundance and richness in macroinvertebrate communities coincided with increases in Microcystis toxicity. Water quality was characterized by high light attenuation values caused by abiogenic turbidity and shading and absorbance from thick algal scums. The study highlights the potential for multidimensional environmental impacts associated with toxic cyanoprokaryote blooms, and the consequent implications for the management of shallow, inland and tropical lakes that are susceptible to toxic blooms. 相似文献
12.
Igor Hudec 《Hydrobiologia》1991,225(1):9-22
European populations of Daphnia similis Claus have been compared with populations from tropical Asia. Daphnia similoides n. sp. from tropical Asia was described as the sibling species of D. similis. The female has characteristic neonate, postabdomen, head, and ephippium. The male has characteristic rostrum, antennules, and the distalmost part of the postabdomen. The D. similis group was compared with D. carinata s. str. Australian populations. 相似文献
13.
Saranya Limkaisang James Henry Cunnington Liew Kon Wui Baharuddin Salleh Yukio Sato Rangsi Divarangkoon Wanwisa Fangfuk Chaiwat To-anun Susumu Takamatsu 《Mycoscience》2006,47(6):327-335
To investigate the phylogenetic relationships among the powdery mildew fungi of some economically important tropical trees
belonging to Oidium subgenus Pseudoidium, we conducted molecular phylogenetic analyses using 30 DNA sequences of the rDNA internal transcribed spacer (ITS) regions
and 26 sequences of the domains D1 and D2 of the 28S rDNA obtained from the powdery mildews on Hevea brasiliensis (para rubber tree), Anacardium occidentale (cashew), Bixa orellana, Citrus spp., Mangifera indica (mango), and Acacia spp. The results indicate that the powdery mildew fungi isolated from these tropical trees are closely related to one another.
These powdery mildews are also closely related to E. alphitoides (including Erysiphe sp. on Quercus phillyraeoides). Because of the obligate biotrophic nature of the powdery mildew fungi, the relationship between powdery mildews and their
host plants is conservative. However, the present study suggests that a particular powdery mildew species has expanded its
host ranges on a wide range of the tropical trees. This article also suggests that a powdery mildew fungus distributed in
temperate regions of the Northern Hemisphere expanded its host ranges onto tropical plants and may be a good example of how
geographical and host range expansion has occurred in the Erysiphales. 相似文献
14.
Sarawood Sungkaew Chris M. A. Stapleton Nicolas Salamin Trevor R. Hodkinson 《Journal of plant research》2009,122(1):95-108
The taxonomy of Bambusoideae is in a state of flux and phylogenetic studies are required to help resolve systematic issues.
Over 60 taxa, representing all subtribes of Bambuseae and related non-bambusoid grasses were sampled. A combined analysis
of five plastid DNA regions, trnL intron, trnL-F intergenic spacer, atpB-rbcL intergenic spacer, rps16 intron, and matK, was used to study the phylogenetic relationships among the bamboos in general and the woody bamboos in particular. Within
the BEP clade (Bambusoideae s.s., Ehrhartoideae, Pooideae), Pooideae were resolved as sister to Bambusoideae s.s. Tribe Bambuseae,
the woody bamboos, as currently recognized were not monophyletic because Olyreae, the herbaceous bamboos, were sister to tropical
Bambuseae. Temperate Bambuseae were sister to the group consisting of tropical Bambuseae and Olyreae. Thus, the temperate
Bambuseae would be better treated as their own tribe Arundinarieae than as a subgroup of Bambuseae. Within the tropical Bambuseae,
neotropical Bambuseae were sister to the palaeotropical and Austral Bambuseae. In addition, Melocanninae were found to be
sister to the remaining palaeotropical and Austral Bambuseae. We discuss phylogenetic and morphological patterns of diversification
and interpret them in a biogeographic context. 相似文献
15.
Information on genetic connectivity and structure of populations in the tropical Pacific is critical for making inferences
about the origins and maintenance of diversity in this region. Sequences of the mitochondrial COI gene from 92 individuals
of the trans-Pacific gastropod Conus ebraeus from eight localities spanning the tropical Pacific were analyzed to determine whether populations in the western, central,
and eastern Pacific exhibit genetic structure, to examine the demographic histories of populations, and to infer patterns
of gene flow. A total of 43 unique haplotypes were recovered, including a common haplotype that occurred in six of the eight
populations examined. AMOVA and pairwise F-statistics showed that populations in the western and central Pacific were significantly differentiated from populations
in the eastern Pacific, but no other evidence of structure. Bayesian isolation–migration (IM) analysis suggested that populations
in the western and central Pacific separated from those in eastern Pacific during the Pleistocene. Examination of mismatch
distributions and results from IM revealed that populations in the western and central Pacific expanded during the Pleistocene.
Gene flow across the East Pacific Barrier appears to occur predominantly westward. 相似文献
16.
The protocols of in vitro cultivation described in the literature for mushrooms are usually correlated with temperate climate
habitat, but it is necessary to study protocols for species of tropical climates. In this article, we collected, isolated,
and evaluated the conditions of in vitro mycelial growth of Lentinus strigosus and correlated these with the characteristics of its habitat. These results indicate, as optimal conditions of in vitro mycelial
growth for L. strigosus, the use of 35°C for incubation, initial pH from 5 to 7, without illumination, Sabouraud dextrose agar medium, and agitation
for culture in liquid medium. 相似文献
17.
Severe climatic events affect all species, but there is little quantitative knowledge of how sympatric species react to such
situations. We compared the reproductive seasonality of sea turtles that nest sympatrically with their vulnerability to tropical
cyclones (in this study, “tropical cyclone” refers to tropical storms and hurricanes), which are increasing in severity due
to changes in global climate. Storm surges significantly decreased reproductive output by lowering the number of nests that
hatched and the number of hatchlings that emerged from nests, but the severity of this effect varied by species. Leatherback
turtles (Dermochelys coriacea) began nesting earliest and most offspring hatched before the tropical cyclone season arrived, resulting in little negative
effect. Loggerhead turtles (Caretta caretta) nested intermediately, and only nests laid late in the season were inundated with seawater during storm surges. Green turtles
(Chelonia mydas) nested last, and their entire nesting season occurred during the tropical cyclone season; this resulted in a majority (79%)
of green turtle nests incubating in September, when tropical cyclones are most likely to occur. Since this timing overlaps
considerably with the tropical cyclone season, the developing eggs and nests are extremely vulnerable to storm surges. Increases
in the severity of tropical cyclones may cause green turtle nesting success to worsen in the future. However, published literature
suggests that loggerhead turtles are nesting earlier in the season and shortening their nesting seasons in response to increasing
sea surface temperatures caused by global climate change. This may cause loggerhead reproductive success to improve in the
future because more nests will hatch before the onset of tropical cyclones. Our data clearly indicate that sympatric species
using the same resources are affected differently by tropical cyclones due to slight variations in the seasonal timing of
nesting, a key life history process. 相似文献
18.
Jeffery A. Foran 《Hydrobiologia》1986,134(2):103-112
The role that temperature plays in excluding large daphnid species from subtropical and tropical ponds, and competitive relationships
between Daphnia laevis and Daphnia magna, are explored. D. magna, a large temperate species is probably not excluded from subtropical or tropical systems by elevated temperatures. However,
D. magna was a poorer competitor, under a restricted set of laboratory conditions, than D. laevis, the only pond dwelling daphnid in subtropical Florida. Competition is proposed as one mechanism that may limit the number
of daphnid species in subtropical and tropical ponds and lakes. Reduced environmental fluctuations in subtropical and tropical
systems (compared with temperate systems) may allow zooplankton populations to reach an environmental carrying capacity where
competition limits the number of similar, coexisting species in a habitat. 相似文献
19.
20.
Angel Valdez-Ortiz Sergio Medina-Godoy M. Elena Valverde Octavio Paredes-López 《Plant Cell, Tissue and Organ Culture》2007,91(3):201-214
An efficient Agrobacterium-mediated transformation system, from which transgenic tropical maize plants were directly generated without previous crosses
with laboratory or temperate lines, was established. Experimental evaluations were focused on two main issues: (i) establishment
of appropriate tissue culture conditions, which induced somatic embryogenesis from the scutellum-cells, and (ii) the delivery
of T-DNA toward these cells. High rates of embryogenic-calli, mainly generated from the embryo-scutellum, were obtained when
15 mg l−1 AgNO3 were included into the N6-based induction medium; rates up to 19 plants per gram were regenerated from these induced calli.
Regarding the Agrobacterium strains evaluated for their transformation capability on the tropical maize line LPC13 used here, best results were obtained
from the EHA105 cells when applied at OD550 nm = 0.5–1.0. Physical microwounds before the Agro-infection proved to be an excellent way to promoting both the T-DNA transferring toward the embryo-scutellum and the increasing
of rates of transient GUS expression. The highest frequencies of transient GUS expression corresponding to the scutellum-cells
as well as the regeneration of whole transgenic plants emerged from them, were obtained using immature embryos wounded by
bombarding at 80 lb/in2 followed for vacuum infiltration before and during the Agro-infection, respectively, or using embryos wounded by 5 s-sonication (without vacuum infiltration) before the Agro-infection. Transformation frequencies up to 5.41% and 6.82% were obtained from the Agro-infected embryos wounded by particle-bombardment and sonication, respectively. Analyses of the progenies confirmed the sexual
transmission of the introduced genes and their stable expression. 相似文献