共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
Embryonic, larval, and juvenile development of two cyprinid species belonging to the Zacco temminckii species' group, Z. temminckii (Temminck and Schlegel) and Zacco sp. (type A), are described and compared with each other from laboratory-reared and wild specimens. The eggs of both species
were closely similar except in diameter [1.92–2.20 mm in Z. temminckii vs. 1.60–1.75 mm in Z. sp. (type A)], being demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk, and no oil
globule. Hatching occurred 40–53 h after fertilization in Z. temminckii and after 47–60 h in Z. sp. (type A). The newly hatched larvae of both species [4.9–5.3 mm in body length (BL) in Z. temminckii and 3.5–4.8 mm BL in Z. sp. (type A)] also resembled each other, having a large transparent pear-shaped yolk and lacking body pigmentation. Myomere
counts of Z. temminckii and Z. sp. (type A) larvae and juveniles were 24–27 + 14–17 = 41–42 and 23–27 + 14–17 = 40–41, respectively. The yolk was completely
absorbed at 8.3 mm BL in Z. temminckii and at 6.6 mm BL in Z. sp. (type A). Notochord flexion was initiated and completed at 7.8 mm BL and 8.2 mm BL in Z. temminckii and at 6.3 mm BL and 6.6 mm BL in Z. sp. (type A), respectively. Aggregate numbers of all fin rays were completed at 17 mm BL in Z. temminckii and 13 mm BL in Z. sp. (type A). Although the morphology of larvae and juveniles of both species was very similar, differences in body length
of each developmental stage, the duration and process of disappearance of the adipose finfold, the anal fin ray counts, and
pigmentation on the lateral body surface were clearly recognized.
Received: August 10, 2001 / Revised: March 14, 2002 / Accepted: March 27, 2002 相似文献
3.
Cedar M. Chittenden Kevin G. Butterworth K. Fiona Cubitt Melinda C. Jacobs Adrian Ladouceur David W. Welch R. Scott McKinley 《Environmental Biology of Fishes》2009,84(1):129-140
Many coho salmon stocks (Oncorhynchus kisutch) have been in decline during the past three decades. Canada’s most endangered salmon stock, the Thompson River coho salmon,
is being studied extensively as managers attempt to reverse these population declines. Investigators are using acoustic telemetry
to track the migratory behaviour and survival of the Thompson River (and other) coho salmon stocks. Coho salmon pre-smolts
are relatively small compared with salmonid species that are typically studied using acoustic telemetry; therefore the identification
of the appropriate sizes of fish and tags to use is critical. This study tested the effects of surgically implanting the three
smallest sizes of acoustic tags currently available on the growth, survival, tag retention, swimming performance and physical
condition of coho salmon pre-smolts for 300 days post-surgery. Maximum tag size to body size ratios ranged from 15–17% by
fork length and 7–8% by mass for the three tag sizes (11 cm fork length for a 6 × 19 mm tag, 12.5 cm for a 7 × 19 mm tag,
and 14 cm for a 9 × 21 mm tag). Based on our results, it is unlikely that coho salmon pre-smolts implanted with acoustic transmitters
following these size guidelines would have poor survival in studies of freshwater migratory behaviour as a result of the surgery
or the tag. 相似文献
4.
Toshihiro Yokoo Kouki Kanou Masato Moteki Hiroshi Kohno Prasert Tongnunui Hisashi Kurokura 《Ichthyological Research》2006,53(4):330-336
Juveniles of three eleotrid Butis species (B. butis, B. humeralis, and B. koilomatodon) are described; their occurrence patterns were examined in Sikao Creek, a mangrove estuary located in southern Thailand.
Juveniles of each species were distinguished by the following characters: B. butis with no bands on body and pale pelvic fins; B. humeralis with no bands on body and densely pigmented pelvic fins; and B. koilomatodon with 5–6 regular bands on body and a fleshy process (preorbital knob) on the snout. Although B. butis shared the aforementioned characters with B. amboinensis found in the same estuary, the former was distinguished from the latter by having a greater number of pectoral fin rays (18–21
vs. 17) and a deeper caudal peduncle. Distribution patterns of the three Butis species in Sikao Creek were distinguishable from each other. Smaller B. butis [mean ± SD = 22.7 ± 16.9 mm in standard length (SL), n = 32] occurred in the upper reach of the estuary, while larger specimens (52.4 ± 26.2 mm SL, n = 18 and 51.5 ± 29.7 mm SL, n = 10, respectively) were found in the middle and lower reaches and none in the marine area. In B. humeralis and B. koilomatodon, only juveniles were caught except for one adult specimen each. Juveniles (8.9–16.5 mm SL, n = 79) of B. humeralis occurred in the upper and middle reaches and the marine area. B. koilomatodon juveniles (9.9–13.7 mm SL, n = 30) were distributed in all areas from the lower to upper reaches. 相似文献
5.
Midori Iida Shun Watanabe Akira Shinoda Katsumi Tsukamoto 《Environmental Biology of Fishes》2008,83(3):331-341
Ecological aspects of recruitment in the amphidromous goby, Sicyopterus japonicus, were studied from larval collections made with a set net in the estuary of the Ota River, Wakayama, Japan. The abundance
patterns of the 12,766 larvae collected from 18 April to 26 August 2006 showed several peaks during the recruitment season.
Their body sizes at recruitment ranged from 23.5 to 30.0 mm standard length (mean ± SD, 26.3 ± 1.1 mm), 0.11 to 0.49 g body
weight (0.22 ± 0.05 g), and 8 to 20 condition factor (11 ± 2). The standard length of the goby larvae tended to decrease with
the season, while their body weight slightly increased and resulted in an increase in condition factor. The recruitment of
larvae occurred mainly during the daytime. Otolith growth increment analysis of 30 larvae collected by a square lift net on
30 April 2005 revealed that the oceanic larval duration after downstream migration ranged from 173 to 253 days (208 ± 22)
after hatching. A limited time of recruitment in early summer and a considerably long duration of oceanic life (about a half
year) appeared to be unique characteristics of this Sicyopterus species that lives in a temperate region in comparison to other tropical species of the genus Sicyopterus that all have year-round recruitment. 相似文献
6.
Lignosus hainanensis sp. nov., is described and illustrated on the basis of collections originating from tropical forest in Hainan Province, southern
China. Both the morphology and phylogeny support this new species. It is characterized by its centrally stipitate basidiocarps
arising from a distinct sclerotium, yellowish brown to cinnamon-brown pileal surface, cream to cream-buff pore surface, trimitic
hyphal system with clamped generative hyphae, and oblong ellipsoid to cylindrical basidiospores. Lignosus hainanensis may be confused with L. rhinocerus, also occurring in southern China, but L. rhinocerus can be distinguished by its smaller pores (6–8 per mm) and smaller and distinctly broadly ellipsoid basidiospores (4–5 × 2.8–3 μm). 相似文献
7.
Vishal Gupta Manoj Kumar Puja Kumari C. R. K. Reddy Bhavanath Jha 《Journal of applied phycology》2011,23(2):209-218
This study reports on the optimization of protoplast yield from two important tropical agarophytes Gracilaria dura and Gracilaria verrucosa using different cell-wall-degrading enzymes obtained from commercial sources. The conditions for achieving the highest protoplast
yield was investigated by optimizing key parameters such as enzyme combinations and their concentrations, duration of enzyme
treatment, enzyme pH, mannitol concentration, and temperature. The significance of each key parameter was also further validated
using the statistical central composite design. The enzyme composition with 4% cellulase Onozuka R-10, 2% macerozyme R-10,
0.5% pectolyase, and 100 U agarase, 0.4 M mannitol in seawater (30‰) adjusted to pH 7.5 produced the highest protoplast yields
of 3.7 ± 0.7 × 106 cells g−1 fresh wt for G. dura and 1.2 ± 0.78 × 106 cells g−1 fresh wt for G. verrucosa when incubated at 25°C for 4–6 h duration. The young growing tips maximally released the protoplasts having a size of 7–15 μm
in G. dura and 15–25 μm in G. verrucosa, mostly from epidermal and upper cortical regions. A few large-size protoplasts of 25–35 μm, presumably from cortical region,
were also observed in G. verrucosa. 相似文献
8.
Jørgen G. Nielsen 《Ichthyological Research》2007,54(4):374-379
A new species of the fish genus Grammonus (Ophidiiformes: Bythitidae) is described based on a ripe female, 98 mm in standard length (SL). It was caught at the bottom
of a cave at a depth of 20 m under lightless conditions in Ie-shima Island, one of the Ryukyu Islands. A comparison to the
seven described species of Grammonus shows the greatest similarity to the widely distributed G. robustus, but G. yunokawai n. sp. differs from it by having fewer vertebrae (41 vs. 44–47), a greater predorsal length (41.5 vs. 32.0–39.0% SL), higher
posterior margin of maxilla (8.4 vs. 5.6–7.3% SL), and greater interorbital width (10.5 vs. 5.9–7.6% SL).
Supplementary material to this paper is available in electronic format at 相似文献
9.
Atherinomorus aetholepis sp. nov. is described from the holotype and 51 paratypes, 44–72 mm in standard length, collected from Indonesian and Philippine
waters. The species is similar to other congeners in general body appearance, especially A. duodecimalis and A. regina, in having a slender body, a tubercle on the posterior end of the dentary, and a narrow midlateral band, but clearly differing
from them in having a long spatular outgrowth on the posterior margins of most of the predorsal and interdorsal scales. Additionally,
the species differs from A. duodecimalis in having a more slender body [body depth 17–22 (mean 19) % SL vs. 19–25 (mean 22) % SL], more midlateral scales [37–40 (mean
38.4) vs. 35–38 (mean 36.6)], more total vertebrae [38–42 (mean 39.9) vs. 36–40 (mean 38.0)], and fewer lower gill rakers
[18–22 (mean 20.2) vs. 20–25 (mean 22.3)], and from A. regina in having more anal fin soft rays (12–14 vs. 9–10).
Electronic supplementary material to this article is available at and accessible to authorized users.
Received: October 22, 2001 / Revised: March 14, 2002 / Accepted: March 26, 2002
An erratum to this article is available at . 相似文献
10.
Two new nematode species, Ascarophis longiovata n. sp. and Neoascarophis longispicula n. sp. (Cystidicolidae), are described from the digestive tract of the marine deep-water fish, the Mediterranean grenadier
Coryphaenoides mediterraneus (Giglioli), from the Mid-Atlantic Ridge. The former species is characterised mainly by the structure of the mouth (large
pseudolabia, each with well-developed dorsal and ventral extension and small apical protrusion; submedian labia almost absent),
the large, elongate-oval, non-filamented eggs (60–66 × 18–27 μm), a cervical inflation of the cuticle, bifurcate deirids,
and the length of the spicules (315–360 and 120–147 μm), whereas the latter (only males available) can be distinguished by
the length of the spicules (960–1,149 and 258–351 μm) and their length ratio (1:1.91–2.71), the shape of the deirids (bifurcate,
with long, narrow posterior arms), and the location of the excretory pore and deirids well posterior to the level of the nerve-ring. 相似文献
11.
The ovaries of the studied 16 viviparous blenny species of the fish family Clinidae (Teleostei, Perciformes) from Australia
and South Africa, are of the cystovarian type and bilobed, ending in a common short oviduct at the gonopore; they are elongated
in juvenile fish, becoming bottle-shaped or oval with maturation and onset of embryogenesis, when they comprise 18–20% of
the total body weight. The ovarian lumen is covered by the germinal epithelium, resting on a basal membrane. The primordial
germ cells are situated along the inner side of each lobe, juxtaposed internally to the lumenal epithelium. Single primary
oocytes or nests of such, each in a follicular envelope and covered externally by the lumenal epithelium forming clusters
protruding into the lumen, along which the inoculated sperm settle. Two different types of reproductive strategies are demonstrated
by the Australian species of Heteroclinus and Cristiceps and the South African species of Clinus and related forms. The Australian species produce high numbers of small (350 ± 50 μm in diameter) eggs that develop synchronously,
while the South African species produce much fewer and larger (1.0 ± 0.1 mm) eggs, asynchronous in development. An exception
in the latter group is Blennophis striatus, with eggs of ca.1.4 mm that develop synchronously. The Australian species are thus mass releasers that bear and release up
to 1000 small (11 ± 1.5 mm in length) embryos/spawn, while the South African Clinus species are discrete releasers that bear eggs of various sizes and small numbers of mature for release embryos that reach
up to 22 mm in length, and are released throughout the year. The cytogenesis of the oocytes and surrounding envelopes is discussed. 相似文献
12.
Atsushi Nanami 《Ichthyological Research》2011,58(4):310-314
The ornate jobfish Pristipomoides argyrogrammicus is an important lutjanid species for fisheries in the Okinawan region of Japan. The present study estimated the size composition
and reproduction of this species in the waters around Ishigaki Island, Okinawa Prefecture. The length–frequency distribution
indicated that males grow larger than females. The fork length (FL; mm)–whole body weight (BW; g) relationship and FL–total
length (TL) relationship were as follows: BW = 1.048 × 10−5 FL3.121 and TL = 1.101 × FL + 2.196, respectively. The main spawning season was estimated as between April and August, since higher
gonadosomatic index (GSI) values were found for both sexes, and matured oocytes were observed in females during these months.
The developmental stage of ovaries correlated with the GSI of females. Fecundity ranged from 9,530 to 98,260 oocytes in fish
of 177.0 to 278.0 mm FL, and the FL–fecundity relationship was as follows: fecundity = 9.525 × 10−8 FL4.903. 相似文献
13.
A new species Dolichopteryx minuscula is described on the basis of three specimens [49.4–59.6 mm in standard length (SL)] collected from the Indo-West Pacific.
The new species is characterized by pouchlike eyes with a small lens (lens diameter 2.2% SL), an adipose fin, the anal fin
base originating posterior to the dorsal fin base, and 16–17 (= 5–6 + 1 + 10–11) gill rakers. Total fecundity was relatively
low, only 658 ova being obtained from one specimen, despite the ovary being mature. Ovarian eggs were clearly subdivided into
“undeveloped” (0.1–0.7 mm diameter classes, n = 561) and “developed” (1.0–1.3 mm classes, n = 97) groups, based on their frequency distribution. Such relatively low fecundity and frequency distributions of ovarian
eggs suggest that Dolichopteryx species spawn iteratively during spawning season. 相似文献
14.
Migration and reproduction of the Caspian Lamprey, Caspiomyzon wagneri, in the Shirud River were investigated during late-March to early-May at water temperatures ranging from 11 to 21.25°C. We
examined the effect of water temperature on timing of spawning migrations. There was a significant negative relationship between
temperature and intensive migration of Caspian Lamprey (p < 0.05). The most intensive migration of lampreys was at night (21:00–3:00 h) and when the water temperatures averaged 16°C
(34.43%). The overall sex ratio (male to female) was 1.07 to 1. The individual absolute fecundity was 31 ‘758–51’ 198 eggs
(mean±SD—41,924 ± 5,382). The egg diameter was 0.780–1.151 (0.92 ± 0.081) mm. The individual relative fecundity varies from
80.3 to 148.1 (107.2 ± 15.1) eggs per 1 mm of length and from 260.8 to 677.4 (397.6 ± 93) eggs per 1 g of weight. The gonadosomatic
index (GSI) of females was 5.83–31.44 (11.22 ± 4.30). 相似文献
15.
Chirita luochengensis, a new species of Gesneriaceae from Guangxi, China, is described and illustrated. The new species is similar to C. linearifolia in leaf shape, but can be distinguished by the apex of leaf blade obtuse to round, corolla purplish, 3–4.2 cm long, corolla
tube 2–2.5 cm long, 10–15 mm diameter at the mouth, staminodes 3, disc ca. 2.5 mm in height, pistil 2.5–3 cm long, stigma
obtrapeziform, 4 mm long, and apex shallowly 2-lobed. 相似文献
16.
Ribitsch D Karl W Wehrschütz-Sigl E Tutz S Remler P Weber HJ Gruber K Stehr R Bessler C Hoven N Sauter K Maurer KH Schwab H 《Applied microbiology and biotechnology》2009,81(5):875-886
In the course of a microbial screening of soil samples for new oxidases, different enrichment strategies were carried out.
With choline as the only carbon source, a microorganism was isolated and identified as Arthrobacter nicotianae. From this strain, a gene coding for a choline oxidase was isolated from chromosomal DNA. This gene named codA was cloned in Escherichia coli BL21-Gold and the protein (An_CodA) heterologously overexpressed as a soluble intracellular protein of 59.1 kDa. Basic biochemical characterization of
purified protein revealed a pH optimum of 7.4 and activity over a broad temperature range (15–70 °C). Specific activities
were determined toward choline chloride (4.70 ± 0.12 U/mg) and the synthetic analogs bis(2-hydroxyethyl)-dimethylammonium
chloride (0.05 ± 0.45 × 10–2 U/mg) and tris-(2-hydroxyethyl)-methylammonium methylsulfate (0.01 ± 0.12 × 10–2 U/mg). With increasing number of oxidizable groups, a significant decrease in activity was noted. Determination of kinetic
parameters in atmorspheric oxygen resulted in K
M = 1.51 ± 0.09 mM and V
max = 42.73 ± 0.42 mU/min for choline chloride and K
M = 4.77 ± 0.76 mM and V
max = 48.40 ± 2.88 mU/min for the reaction intermediate betaine aldehyde respectively. Nuclear magnetic resonance spectroscopic
analysis of the products formed during the enzyme reaction with choline chloride showed that in vitro the intermediate betaine
aldehyde exists also free in solution. 相似文献
17.
The influence of predator exposure on the survival of hatchery red drum, Sciaenops ocellatus was investigated under laboratory conditions. Several prey-capture (attack distance, mean attack velocity, capture time,
and gape cycle duration) and anti-predator (reaction distance, response distance, mean velocity, and maximum velocity) performance
variables were quantified using high-speed video for juvenile red drum (25–30 mm standard length, L
S
) reared with and without predators (pinfish, Lagodon rhomboides). Univariate contrasts of prey-capture events demonstrated that attack distance (mean ± s.e.) was significantly greater in
red drum reared with (1.20 ± 0.16 mm) versus without (0.65 ± 0.09 mm) pinfish predators. During anti-predator events, red
drum reared with predators had approximately 300% greater reaction distance and 20%–30% greater response distance, mean velocity
and maximum velocity versus fish reared without predators; however, these differences were not statistically significant.
Following video assessments, a series of mortality experiments were conducted using free-ranging pinfish predators. Mortality
rates (Z) ranged from 0.047 to 0.060 (Z/hr/predator) and did not differ significantly among treatments. 相似文献
18.
Daphnid morphology deters fish predators 总被引:3,自引:0,他引:3
Spine and helmet production in zooplankton are thought to provide protection from invertebrate rather than vertebrate predators.
We examined selectivity for Daphnia lumholtzi, a species that exhibits extreme cyclomorphosis with a large helmet and long tail spine (total length can exceed 5 mm), by
juvenile bluegill (15–80 mm) in the laboratory and field. Bluegill consumed more D. pulex than D. lumholtzi when the species were presented alone. When the daphnids were offered together in equal numbers, bluegill selected against
D. lumholtzi. Bluegill foraging behavior helped explain the observed nonrandom feeding. Bluegill capture efficiency foraging on D. pulex was high (85–100%) and handling times were low (usually too short to detect), whereas efficiencies were lower (40–96%) and
handling times were longer (1–3 s) when foraging on D. lumholtzi, particularly for fish <50 mm. As they gained experience, bluegill <50 mm that oriented towards D. lumholtzi rejected them more often than striking. In addition, more D. lumholtzi were rejected and expelled than were D. pulex. From these experiments, we conclude that larger bluegill (>50 mm) are able to forage more successfully on D. lumholtzi than smaller fish. Selectivity by bluegill collected from a reservoir infested with D. lumholtzi verified our laboratory conclusions. Smaller bluegill selected against D. lumholtzi, whereas it was a preferred diet item for bluegill >50 mm. These results show that the morphology of D. lumholtzi interferes with predation by small planktivorous fish, posing foraging constraints for these fish more similar to those of
piscivores, where handling time is important, than to those of planktivores, where prey density is of primary importance.
Received: 13 August 1998 / Accepted 21 August 1998 相似文献
19.
Keisuke Obase Joo Young Cha Jong Kyu Lee Sang Yong Lee Jin Ho Lee Kun Woo Chun 《Mycorrhiza》2009,20(1):39-49
We investigated the ectomycorrhizal (ECM) fungal colonization status of Pinus thunbergii mature trees and regenerating seedlings varying in age in coastal pine forests on the east coast of Korea. We established
one 20 × 20-m plot at each of two study sites at P. thunbergii coastal forests in Samcheok. Fifty soil blocks (5 × 5 × 15 cm) were sampled at regular intervals, and ten P. thunbergii seedlings of age 0, 1–3, 3–5, and 5–10 years were sampled in each study plot. In total of 27 ECM fungal taxa, Cenococcum geophilum was dominant, followed by Russula sp., Sebacina sp., and unidentified Cortinuris sp. in mature trees. In 0-year-old seedlings, some fungal species such as Sebacina sp., C. geophilum, and unidentified Cortinarius sp. were dominant whereas only C. geophilum was dominant after 1 year, and there were no apparent succession patterns in ECM fungal compositions beyond a host age of
1 year. Most ECM fungal taxa that had colonized seedlings of each age class were also observed in roots of mature trees in
each site. These taxa accounted for 86.7–100% and 96.4–98.4% of ECM abundance in seedlings and mature trees, respectively.
The results indicate that the species composition of ECM fungal taxa colonizing seedlings of different age in forests is similar
to that of surrounding mature trees. Our results also showed that C. geophilum is a common and dominant ECM fungus in P. thunbergii coastal forests and might play a significant role in their regeneration. 相似文献
20.
Espino-Paisan L de la Calle H Fernández-Arquero M Figueredo MA de la Concha EG Urcelay E Santiago JL 《Immunogenetics》2011,63(4):255-258
The Wellcome Trust Case Control Consortium (WTCCC) genome-wide study found association of PTPN2 with three autoimmune diseases, among them is type 1 diabetes (T1D). This result was confirmed by a follow-up study that
pointed to new independent signals within the region. However, both studies were performed in patients with an early-onset
T1D. We aimed at replicating the previous results and studying the influence of these polymorphisms in the age at T1D debut.
We genotyped 439 T1D Spanish subjects (age at onset, 1 to 65 years) and 861 controls for two PTPN2 single nucleotide polymorphisms (SNPs), rs2542151 and rs478582, and studied the effect of both polymorphisms in age at onset
through stratified and continuous analyses. The frequency of rs2542151*G carriers was significantly higher in the early-onset
group compared with late-onset patients (p = 0.023) and with controls (OR = 1.61 [1.14–2.26]; p = 0.005). No significant differences were found between controls and late-onset patients. The log-rank chi-square test for
the Kaplan–Meier plots (carriers of susceptibility allele vs non carriers) was statistically significant (χ
1df2 = 4.485; p = 0.034), yielding an earlier disease debut for G carriers. The analysis of the SNP rs478582 did not reach statistical significance.
In summary, we replicate the association detected by the WTCCC and propose that the rs2542151*G allele confers risk to an
earlier onset of T1D. 相似文献