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.
The diet of the grey heron (Ardea cinerea) was investigated in three colonies in northern Poland (Mosty, Kiersity and Kty Rybackie) varying in size, habitat type and composition of feeding areas used by birds. The diet was assessed during the breeding season on the base of pellets and regurgitated food. Pellets from all studied colonies consisted mainly of mammal hair (almost 100% of samples), bone remains (20–24%) and invertebrate remains (26–51%, mainly water beetle, Dytiscus marginalis). Bones and hair of water vole (Arvicola terrestris) and Microtus voles were the most common remains of mammals recorded in pellets. Remains of other animal taxa were found sporadically. In the colonies at Mosty and Kiersity, fish composed more than 95% of collected regurgitated prey items. Food consumption of herons from the biggest colony at Kty Rybackie was estimated to exceed 100 t per season. Herons from Mosty consumed ca 46–52 t, from Kiersity 30–38 t of food per season. The impact of herons on fish communities was much lower than other losses due to predation (herons from Kty Rybackie caught only 6% of fishermen bycatch, birds from Mosty took 10–14% of round gobies eaten by cormorants).  相似文献   

2.
The life cycles of two separate populations (colonies A and B) of the rabbit tick, Haemaphysalis leporis-palustris, were studied under laboratory conditions. Domestic New Zealand rabbits, Oryctolagus cuniculus, and wild rabbits, Sylvilagus brasiliensis, were used as hosts for ticks from colony B and only O. cuniculus rabbits were used as hosts for ticks from colony A. Developmental periods were observed in an incubator at 27±1°C and RH 90±5%. Larvae from colonies A and B fed for 8.0±3.7 days and 8.5±1.3 days, respectively, on O. cuniculus. On S. brasiliensis larvae from colony B fed for 7.2±1.3 days. Nymphs from colony A fed for 8.1±1.4 days on O. cuniculus and nymphs from colony B fed for 8.1±1.0 days on S. brasiliensis. Only one engorged nymph from colony B was recovered from O. cuniculus. Females from colony A fed for 20.9±5.9 days on O. cuniculus and females from colony B fed for 18.6±2.4 days on O. cuniculus and 18.7±3.7 days on S. brasiliensis. Engorged larvae from colony A required 13.7±3.7 days to molt while engorged larvae from colony B required 11.8±3.0 and 11.5±1.8 days to molt, after having fed on O. cuniculus and S. brasiliensis, respectively. Engorged nymphs from colonies A and B required 16.3±1.9 days and 14.7±1.4 days to molt, respectively. Engorged females from colonies A and B required 4–7 and 3–5 days, respectively, to start oviposition. Mean egg incubation periods lasted for 33–34 days. For ticks from colony B, host species accounted for significant differences (p<0.05) in larval and nymphal feeding periods, oviposition weights and CEIs. Significant differences (p<0.05) between the two colonies when ticks fed on O. cuniculus were observed for larval and nymphal feeding and premolt periods, engorged female and oviposition weights and conversion efficiency indexes (CEI). S. brasiliensis were always a more suitable host for H. leporis-palustris than O. cuniculus. Significantly more larvae and nymphs engorged and molted when fed on S. brasiliensis (p<0.001). Females fed S. brasiliensis were more successful to lay fertile eggs and showed the highest engorged and egg mass weights, and the highest CEIs. Data of H. leporis-palustris fed on wild rabbits (one of its natural host species) are reported for the first time.  相似文献   

3.
Summary Crude protein extracts from single seeds of nondomesticated Mexican bean accessions were analysed by SDS polyacrylamide gel electrophoresis for variability in phaseolin protein. Six new phaseolin types; M1, M2, M3, M4, M5, M6, which contained polypeptides within the same range of molecular weights (51,000 to 45,000 daltons) as occur in the S, T and C phaseolin types of cultivated beans were identified. No T and C types were found among the non-domesticated Mexican accessions, and the S type occurred in less than 7% of the seeds screened. Genetic analyses of F2 progenies from crosses between Sanilac (S), and five of the M types showed that each M phaseolin phenotype was allelic to the S type and expressed codominantly.  相似文献   

4.
A comparative study of the number and distribution of chromocentres in interphase nuclei and mean chiasma frequency at diakinesis has been made in three varietal populations of radish (Raphanus sativus L.), Scarlet Globe, Japanese White and Chinese White. The study showed a significant difference between the varietal populations in mean chiasma frequency and number of chromocentres (P<0.001), indicating that these nuclear characters are genotypically controlled. The correlation analysis revealed a significant negative correlation between chromocentres and chiasma frequency (r= -0.87). It was concluded that an increase in the amount of constitutive heterochromatin, as inferred by chromocentre counts, adversely affects the chiasma frequency and, consequently, genetic recombination in radish.  相似文献   

5.
Summary The neo genes of Tn5 and Tn903 (Tn601) coding for amigoglycoside phosphotransferase type II and type I, respectively, were joined to the yeast adc 1 promoter and trp1 terminator and introduced into yeast (Saccharomyces cerevisiae) cells. Transformants were obtained by direct selection for G418 resistance. Plasmids containing the Tn5 neo gene induced antibiotic resistance only at low frequency, whereas colonies transformed with the Tn903 neo gene could be selected at high frequency (300–400 transformants/g plasmid DNA). The resistance threshold of transformed strains was increased to 30 mg G418/ml by both genes and high level expression of the bacterial genes in yeast could be shown using an in vitro phosphotransferase assay. The results indicate that this system can be used for high frequency transformation of wild-type strains and might in addition be used for the identification and isolation of promoter-active sequences.Abbreviations adc 1 alcoholdehydrogenase I gene - APH aminoglycoside-3-phosphotransferase - leu2 -isopropylmalate dehydrogenase gene - neo aminoglycoside-3-phosphotransferase gene - trp1 N-(5-phosphoribosyl)-anthranilate isomerase gene Dedicated to Prof. Dr. Dr. h. c. Karl Esser on the occasion of his 65th birthday  相似文献   

6.
Summary An exotic Zea mays L. population (Tuxpeno) was adapted to North Carolina conditions by first introducing genes for adaptability from two North Carolina varieties ([(Jarvis X Indian Chief)Tuxpeno]Tuxpeno) including four generations of intermating, and then selecting for adaptability using maturity as the primary measure. The study evaluated selection for adaptability and the diversity available between adapted Tuxpeno and the local varieties, Jarvis and Indian Chief. Analytical procedures were developed to quantify the diversity between populations and the complementation of local varieties by introduced germ plasms. The analyses utilized the specific effects available from the diallel mating design.Three replicate selections responded similarly under simple recurrent mass selection (1/10) for the earliest disease-free plants initially and additionally for plant types (primarily height) in the final generation. The 1/4 local germ plasm permitted rapid adaptation of Tuxpeno gene pool to local conditions. The adapted Tuxpeno populations yielded similarly to the local populations with an average heterosis for grain yield of 28% when crossed to the local populations used as source of genes for adaptability. The diversity found between adapted Tuxpeno lines and these local varieties based on genes affecting grain yield was 1.5 to 2.5 times that measured between the local varieties (Jarvis and Indian Chief). Diversity lost through intergradation with local material was a reasonable investment. Yield genes introduced from Tuxpeno complemented local gene pools through nonadditive, primarily dominance-associated, gene effects. Reassortment of major gene blocks apparently occurred leading to significant divergence among replicate selections involving both additive-associated and dominance-associated gene effects.Paper No. 6355 of the North Carolina Agri. Res. Ser., Raleigh, NC. Research supported in collaboration with the Rockefeller Foundation and CIMMYT, D.F. (Mexico)  相似文献   

7.
A new neoglycopeptide was synthesized and tested for its capability to bind to lactose permease of Escherichia coli and to inhibit the transport of lactose. The free 5- carboxypentyl-1-thio--D-galactopyranoside or the protected 2,3,4,6-tetra-O-acetyl-5-carboxypentyl-1-thio--D- galactopyranoside was linked to the N-terminal -amino group of the resin bound heptapeptide H-Phe-Phe-Gly-Gly-Gly-Gly-Ala-OH by different activation methods. Upon cleavage from the resin, deacetylation and purification, a neoglycopeptide which showed a significant inhibition of lactose permease was obtained.  相似文献   

8.
Summary A densimeter technique was used to measure the rate of exit of thiourea from erythrocytes of various species of mammals. The cells were first equilibrated with a 200mm thiourea solution in 1% NaCl. An aliquot of these cells was added to 1% NaCl containing 4.6–23.1mm thiourea. Facilitated diffusion was demonstrated in each case. Using exit times or initial rates, calculations of half-saturation constants () inmm and maximum transport rates (K) in isotones per min were made by three different methods. The following values were obtained: human –=60, 42, 35;K=1.2, 2.9, 0.9; rabbit –=46, 33, 32;K=0.8, 2.1, 0.8; mouse –=46,40, 30;K=3.4, 8.5, 3.2; rat –=65, 42, 23;K=6.1, 15.3, 3.7; ox –=107, 63, 88;K=0.6, 1.4, 0.4; sheep –=56, 38, 56;K=0.9, 2.2, 0.6; and pig –=110, 64, 49;K=1.6, 3.6, 1.1.  相似文献   

9.
A new indigenous soil bacterium Pseudomonas sp. growing on phenol and on a mixture of phenol, toluene, o-cresol, naphthalene and 1,2,3-trimethylbenzene (1,2,3-TMB) was isolated and characterized. Phylogenetic analysis suggested its classification to Pseudomonadaceae family and showed 99.8% DNA sequence identity to Pseudomonas pseudoalcaligenes species. The isolate was psychrotroph, with growth temperatures ranging from ca. 0 to 40 °C. The GC–MS structural analysis of metabolic products of phenol degradation by this microorganism indicated a possible ortho cleavage pathway for high concentrations (over 200 mg L–1) of phenol. Biodegradation rates by this species were found to be three times more effective than those previously reported by other Pseudomonas strains. The effect of temperature on phenol degradation was studied in batch cultures at temperatures ranging from 10 to 40°C and different initial phenol concentrations (up to 500mgL–1). Above 300mgL–1 of initial phenol concentration no considerable depletion was recorded at both 10 and 40°C. Maximum degradation rates for phenol were recorded at 30°C. The biodegradation rate of phenol was studied also in the presence of additional carbon sources (o-cresol, toluene, naphthalene, 1,2,3-TMB) at the optimum growth temperature and was found significantly lower by a factor of eight in respect to the strong competitive inhibition between the substrates and the more available sources of carbon and energy. The Haldane equation =m S/(KS+S+S2/KI) was found to best fit the experimental data at the optimum temperature of 30°C than the Monod equation with kinetic constants m=0.27h–1, KS=56.70mgL–1, KI=249.08mgL–1.  相似文献   

10.
Genetic linkage maps of the guppy (Poecilia reticulata) were constructed from independent crosses between the Tuxedo strain and a feral line (Wildtype). Segregation patterns of random amplified polymorphic DNA (RAPD) markers and phenotypic markers were investigated in F2 offspring of Tuxedo × Wildtype and Wildtype × Tuxedo crosses. Among the 300 and 276 RAPD markers scored for the respective crosses, linkages were identified for 230 and 212, respectively. The Tuxedo × Wildtype and Wildtype × Tuxedo maps spanned 2100 Kosambi centiMorgans (cMK) and 1900 cMK, respectively, in 28 linkage groups. Average marker resolution was 10 cMK. Genome length was estimated at 4410 cMK and 4060 cMK for the respective crosses, with an average physical distance of 166 kbp/cMK. Several RAPD markers were closely linked to or mapped onto the loci for the sex-determining region (SdR), and the sex-linked black caudal-peduncle (Bcp) and red tail (Rdt) genes. These primary linkage maps are the initial step toward the construction of a composite high-density map to facilitate map-based cloning and marker-assisted selection of quantitative trait loci that are essential for the development of comprehensive breeding programs for the guppy.  相似文献   

11.
The mangrove killifish Rivulus marmoratus was reared at 25°±1°C and 17ppt salinity from 0 to 100 days after hatching (DAH), and its early development was described by examining growth and morphometric parameters, meristic characters (vertebral and fin-ray counts), bone-cartilage development, and pigmentation. Growth was isometric for preanal length, head length, snout length, body depth, pectoral-fin length, dorsal-fin length, anal-fin length, and caudal-peduncle depth. Negative allometric growth was observed in eye diameter and gape size. Meristic counts (mean±SD) for vertebrae (34.2±0.4) and dorsal- (8.6±0.5), anal- (11.4±0.5), and caudal-fin rays (30.2±0.8) were complete at 0 DAH (n=5), whereas pectoral-fin rays and pelvic-fin rays were complete by 30 DAH (14.5±0.4, n=5) and 60 DAH (4.2±0.8, n=5). Full ossification of meristic elements proceeded in the following sequence: vertebrae (by 30 DAH), caudal-, dorsal-, and anal-fin rays (by 60 DAH), pectoral-fin rays (between 60 DAH and 100 DAH), and pelvic-fin rays (by 100 DAH). Both morphological characters and meristic counts indicate that this species can be considered to be a juvenile after 9.8mm in standard length (20 DAH).  相似文献   

12.
Summary The induction of the cytoplasmic petite mutation by ultraviolet light in 21 UV-sensitive (rad) nuclear mutants of Saccharomyces cerevisiae was compared to that in the wild type. Six rad mutants showed an increased sensitivity and two were less sensitive than the wild type. Modifications in the dose-response paralleled that of UV-induced reversion in one nuclear locus (hi 1) studied. In these eight mutants the repair of UV-induced mitochondrial lesions seems to be under nuclear control.A block in the repair steps controlled by eleven of the other rad genes studied did not interfere with the repair of mitochondrial damage. In strains carrying a mutation in any one of these genes the dose-response curve for petite induction could be superimposed on that of the wild type even though they differed from the wild type in respect of nuclear gene reversion. These steps of the mitochondrial repair pathway(s) are therefore likely to be controlled by a nuclear and/or a cytoplasmic genetic determinant whose product acts specifically on mitochondrial lesions or it may be that the products of these genes are not required in the process of induction of petites.  相似文献   

13.
Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.  相似文献   

14.
Ueda T  Naoi H  Arai R 《Genetica》2001,111(1-3):423-432
In bitterlings (Acheilognathinae) C- and Ag-banding karyotypes of 6 species-subspecies collected in China and South Korea were analyzed. The chromosomal constitution of 2n=46 (4SM+42ST) in Rhodeus atremius fangi was quite different from that of 2n=48 (8M+20SM+20ST) in other species-subspecies in Rhodeus. It was concluded from the analysis of banded chromosomes that the increase in number of ST during the karyotype change from 2n=48 to 2n=46 was achieved by a series of pericentric inversions from 24 M-SM to 24 ST, and the decrease in the diploid number was caused by an additional tandem fusion of 4 ST chromosomes, forming a new ST pair in the 2n=46 karyotype. The karyotype of Tanakia koreensis, T. signifer, and Acheilognathus macropterus is 2n=48 (8M+20SM+20ST), 2n=48 (8M+20SM+14–16ST+4–6 A), 2n=44 (14M+16SM+14ST), respectively. In R. ocellatus ocellatus, T. koreensis, T. signifer and A. macropterus, karyotype changes from 2n=48 to 2n=44 due to centric fusion and inversion have also been estimated. It was suggested that C-banding heterochromatin was greatly concerned with the karyotype evolution in bitterlings.  相似文献   

15.
O. M. Lindstrom  J. V. Carter 《Planta》1985,164(4):512-516
Electrolyte leakage was measured in hardened and nonhardened leaves of three potato species, Solanum tuberosum L., S. acaule Bitt. and S. commersonii Dun., and one interspecific cross, Alaska Frostless (S. acaule x S. tuberosum) when exposed to various subzero temperatures. The leaves were undercooled (no ice present) from 0°C to -12.5°C for 45 min and to-4°C for up to 10 d. Regardless of the degree of undercooling no injury was observed in any of the potatoes, hardened or nonhardened, for up to 12 h. After 5 d, however, electrolyte leakage was observed in hardened S. tuberosum, S. acaule and S. commersonii, and in nonhardened Alaska Frostless. After 10 d exposure all potatoes, hardened and nonhardened, showed a significant amount of electrolyte leakage as compared to their controls kept at 0°C for 10 d.Scientific Journal Series Paper No. 13842 of the Minnesota Agricultural Experiment Station, St. Paul, Minn  相似文献   

16.
In hippocampal neurons, 5-hydroxytryptamine (5-HT) activates an inwardly rectifying K+ current via G protein. We identified the K+ channel activated by 5-HT (K5-HT channel) and studied the effects of G protein subunits and nucleotides on the K+ channel kinetics in adult rat hippocampal neurons. In inside-out patches with 10 m 5-HT in the pipette, application of GTP (100 m) to the cytoplasmic side of the membrane activated an inwardly rectifying K+ channel with a slope conductance of 36±1 pS (symmetrical 140 mm K+) at –60 mV and a mean open time of 1.1±0.1 msec (n=5). Transducin activated the (K5-HT) channels and this was reversed by -GDP. Whether the K5-HT channel was activated endogenously (GTP, GTPS) or exogenously (), the presence of 1 mm ATP resulted in a 4-fold increase in channel activity due in large part to the prolongation of the open time duration. These effects of ATP were irreversible and not mimicked by AMPPMP, suggesting that phosphorylation might be involved. However, inhibitors of protein kinases A and C (H-7, staurosporine) and tyrosine kinase (tyrphostin 25) failed to block the effect of ATP. These results show that G activates the G protein-gated K+ channel in hippocampal neurons, and that ATP modifies the gating kinetics of the channel, resulting in increased open probability via as yet unknown pathways.  相似文献   

17.
The cRNA for Torpedo californica Na+/K+-ATPase -subunit (cRNA) was injected into Xenopus oocytes alone or with the cRNA for the Na+/K+-ATPase -subunit (cRNA). When cRNA was injected alone, the amount of the -subunit that accumulated in oocytes increased with increasing amounts of injected cRNA. When cRNA and cRNA were injected simultaneously, less -subunit accumulated than when cRNA was injected alone, whereas the Na+/K+-ATPase activity increased markedly. The decrease in the accumulation of the -subunit was dose-dependent upon the cRNA. The mutant -subunit unable to assemble with the -subunit accumulated in oocytes independently of cRNA, suggesting that post-translational control mechanisms may serve to reduce the accumulation of the -subunit.This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan (No. 05259226, No. 06454149).  相似文献   

18.
Summary Studies on callus growth and shoots/cotyledon, using seven different genotypes of pigeonpea and their hybrid progenies, revealed continuous variation for these traits. Hence, the type of gene action influencing in vitro cell proliferation and differentiation has been investigated in a diallel analysis of seven pigeonpea genotypes. Highly significant average heterosis was recorded for callus growth and seed yield/plant. In general, the F1 hybrids which showed heterosis for callus growth also exceeded their better parent for yield/ plant. Combining ability analysis revealed both additive and non-additive gene effects for callus growth, while number of shoots/cotyledon was mostly governed by non-additive gene effects. The genotype, ICP 7035, was the best general combiner for callus growth and shoot forming capacity of cotyledons. Two cross combinations, 7186×6974 and 7035×T-21, showed maximum SCA effects for callus growth and shoots/cotyledon. Callus dry weight was positively correlated with seed yield/plant and seedling weight. The strong positive association of callus growth with seed yield indicates the possibility of using this system for mass screening and selection of superior hybrids.  相似文献   

19.
Zusammenfassung Das Muster in den Calcitindividuen des Eischalenkalkes der Vögel-seine Entstehung wird kurz erläutert — kann durch Spalten, Verwachsungsnähte, Anordnung der Globularinklusionen ohne weiteres hervortreten, läßt sich aber auch durch bestimmte Eingriffe, z. B. Ätzen, verdeutlichen. Quer- und Flachschliffe der Eischale von Diomedea exulans (Albatros) zeigen im Bereich der Säulenlage ein ausgeprägtes Globularmuster:In den Primen der Inneren Säulenlage erscheinen am Querschliff die Inklusionen in Parallelstreifen, die schräg gegen die Schalenoberfläche verlaufen, wobei die Neigung von einem zum anderen Prisma wechselt. Jede Reihe dieses Streifenmusters setzt sich aus rhombischen Elementen zusammen, derart, daß das eine Paar der Rhombenseiten die Längsränder des Streifens liefert, das andere aber, schräg über ihn verlaufend, seine Elemente trennt. Die Girlandenzone der Inneren Säulenlage wird durch den genannten Neigungswechsel des — hier vergröberten — Streifenmusters erzeugt.In der Äußeren Säulenlage häufen sich die Globularinklusionen in rechteckigen oder rhombischen Feldern an, die innerhalb des gleichen Prismas parallel stehen. Die Felder sind durch schmale helle inklusionsfreie Raine getrennt, in denen Verwachsungsnähte sich zeigen können. Dieses Block- oder Rhombenmuster ist auch am Flachschliff sichtbar.Der Übergang vom Streifenmuster der Inneren zum Rhomben- oder Blockmuster der Äußeren Säulenlage vollzieht sich über eine die Elemente durchschneidende Schichtlinie hinweg, ohne Störung der optischen Einheitlichkeit des Prismas. So kann das gleiche Musterelement unterhalb der Schichtlinie das Streifen-, oberhalb derselben das Blockmuster darbieten. Sowohl bei den Inneren wie bei den Äußeren Säulenprismen erfolgt die seitliche Verfugung der Nachbarn unter dem Einfluß des Musters, was bei den Inneren Säulen zackigen, bei den Äußeren mehr glatten Grenzverlauf erzeugt. Oft brechen Musterelemente an den Prismengrenzen ab. Manche Prismen der Inneren Säulenlage erscheinen am Flachschliff rhombisch umrissen. Auch am hügeligen Relief der Schalenoberfläche treten Rhombengrenzen hervor.
Summary The pattern in the calcite individues of the avian egg shell — its development is shortly explained — can appear by clefts, outgrowing sutures, arrangement of the globular inclusions, but also can be rendered conspicuous by certain treatments, e.g. etching. Transverse and tangential ground sections through the egg shell of Diomedea exulans (albatros) show in the column layer a characteristic globular pattern.In the prisms of the inner column layer the inclusions are arranged on transverse sections in parallel stripes, running obliquely against the shell surface, whereby its inclination changes from one to the other prism. Each row of this stripe pattern is composed by rhombic elements, so that one pair of the rhomb sides form the longitudinal edges of the elements but the other, obliquely cutting the stripes, separate the elements. The garland zone of the inner column layer is the expression of the alternating inclination in the stripe pattern — here more coarse.In the outer column layer the globular inclusions are accumulated in rectangular or rhombic areas parallel within the same prism. The elements of this block or rhomb pattern are separated by narrow light inclusion-free hiels, in which outgrowing sutures can appear; the pattern is also visible in tangential ground sections.The transition of the stripe pattern to the rhomb or block pattern happens on a stratification line — without disturbance of the the uniform extinction of the prism between crossed polars. Thereby the same pattern element can show under the stratification line the stripe pattern and above it the block pattern. In the inner as in the outer column prisms the lateral indentation of the neighbours is determined by the pattern, producing in the inner columns a pronged, in the outer a more smooth boundary. Often pattern elements break off at the prism boundaries. Some prisms of the inner column layer show a rhombic contour in tangential ground sections. Also on the hilly relievo of the shell surface rhombic limitation is observable.
  相似文献   

20.
Zusammenfassung Die Retinula im Ommatidium der Mehlmotte besteht aus einer wechselnden Anzahl (9–12, meist 11) langgestreckter, prismatischer Sinneszellen. Außerdem enthält jede Retinula nahe der Basalmembran im Zentrum zwischen diesen distalen Retinulazellen noch eine basale Retinulazelle. Die Längsachse der Retinula wird von der Achsenstruktur eingenommen, die aus Mikrovilli besteht. Ihr distaler Teil ist der Achsenfaden, der breitere, proximale Teil bildet das Rhabdom. Dieses erscheint im Querschnitt meist vierstrahlig gelappt, da seine Außenseite in Längsrichtung tief gekehlt ist. Der Rhabdomquerschnitt gliedert sich in mehrere Schöpfe parallel angeordneter Mikrovilli (Rhabdomsektoren); jeder Rhabdomsektor besteht aus 1 oder 2 Rhabdomeren. Die basale Retinulazelle entsendet einen kleinen Schopf von Mikrovilli in die proximale Spitze des Rhabdoms. Die distalen Retinulazellen setzen sich proximal in Neuriten fort, welche sich in Einkehlungen der basalen Retinulazelle bzw. der Tracheenendzelle einschmiegen. Jeweils eine Tracheole durchbricht zusammen mit dem Neuritenstrang einer Retinula die Basalmembran; sie verzweigt sich distal zu ca. 30 Tracheolen, die die Retinula umhüllen.Die Kristallkegelzellen grenzen distal an die Cornea; proximal laufen die Kristallkegelzellen eines Ommatidiums in einen gemeinsamen Fortsatz aus, der zwischen den Retinulazellen unmittelbar am Achsenfaden endet. — Nur das helladaptierte Auge wurde untersucht. Hierbei erscheint im distalen Teil der Retinula nur der Achsenfaden lichtdurchlässig, das Cytoplasma der Retinulazellen hingegen von Pigmentgrana durchsetzt und für Licht undurchlässig.
Fine structure of the eye of the meal moth, Ephestia kuehniella Zeller (Lepidoptera, Pyralididae)
Summary In each ommatidium of the meal moth a retinula is formed from a varying number (9–12, mostly 11) of elongated, prismatic sense cells. In addition, a basal retinular cell is situated near the basement membrane in the center of the other (distal) retinular cells. The axis of the retinula is occupied by many microvilli forming the axial structure, the distal section of which is the slender axial thread. Proximally, the axial structure widens (to 8.5 m instead of 1 m in diameter) and is now called rhabdom. Cross sections of the rhabdom mostly look like a petaloid with four petals; this figure is due to longitudinal infoldings along the length of the rhabdom surface. The rhabdom cross section is subdivided into several brushes of microvilli (rhabdom sectors), each one being characterized by an approximately parallel arrangement of its microvilli. One rhabdom sector may be composed of one or two rhabdomeres respectively.The basal retinular cell participates in rhabdom formation through a small brush of microvilli at the proximal end of the rhabdom. Proximally, the distal retinular cells taper into slender neurites which are embedded in grooves at the surface of the basal retinular cell and the tracheal end cell respectively. One tracheole piercing the basement membrane together with the neurites of one retinula branches into about 30 tracheoles surrounding the retinula.The crystalline cone cells touch the cornea; proximally, their cytoplasm forms a point which eventually terminates amongst the distal tips of the retinular cells, immediately at the axial thread.—Our work was restricted to light adapted eyes; in this condition, light transmission in the distal part of the retinula seems to be blocked by retinular cell pigment except inside the axial thread.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.  相似文献   

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