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91.
92.
Metabolic rate in diapause and nondiapause brown locust eggs correlated with embryonic development 总被引:1,自引:0,他引:1
INNOCENT N. KAMBULE SHIRLEY A. HANRAHAN FRANCES D. DUNCAN 《Physiological Entomology》2011,36(4):299-308
Insects use dormancy to survive adverse conditions. Brown locust Locustana pardalina (Walk.) eggs offer a convenient model to study dormancy (diapause and quiescence), which contributes to their survival under arid conditions. The metabolic rates of developing nondiapause, diapause and quiescent eggs are compared in the present study using closed‐system respirometry. The embryo becomes committed to continue development and hatch or to enter diapause 6 days after the eggs are placed on moist soil. The metabolic rate of nondiapause eggs increases exponentially until hatching, whereas that of diapause eggs is low and stable. The metabolic rate of diapause laboratory eggs (1.9 ± 0.6 µL CO2 mg?1 h?1) is significantly higher than that of field eggs (0.5 ± 0.3 µL CO2 mg?1 h?1), although the ranges of metabolic rate overlap and the embryos are all in late anatrepsis. The metabolic rate of quiescent eggs is similar to that of diapause eggs but decreases with time. Low metabolic rates during arrested development allow eggs to persist over long periods before hatching. 相似文献
93.
Bird A.F. and Stynes B.A. 1981. The life cycle of Anguina agrostis: Development in the host plant. Internationaljournal for Parasitology11: 431–440. The growth and development of the infective second stage “dauer” larvae (DL2) of Anguina agrostis into adults have been followed under field conditions in rye grass (Lolium rigidum). Three moults were observed to occur during the parasitic phase of development. From the third (second parasitic) moult onwards, there was much more variability in the size of the female nematodes than in the males and sexual dimorphism became very pronounced. The transition from the DL2 to the second stage parasitic larva (PL2) is marked by the disappearance of the numerous lipid storage granules which are characteristic of the DL2, and the development in the PL2 of an intestine which becomes more pronounced in each succeeding stage, particularly in the adult female. Anguina agrostis is unusual among parasitic nematodes in that the DL2 has the thickest cuticle of all stages, including adults. The L4 and adult males have thicker cuticles than the females at the same stages of development. Moulting appears to involve resorption of the innermost basal zone of the shed cuticle as well as morphological and chemical changes to the epicuticle. 相似文献
94.
Michael Gudo 《Theorie in den Biowissenschaften》2002,121(1):101-137
Summary The critical theory of evolution was developed by a group of scientists working together with Wolfgang F. Gutmann at the Senckenberg-Research-Institute
in Frankfurt am Main. Gutmann worked at Senckenberg for 37 years. In this time he presented 247 contributions which are distributed
over 47 periodicals and books. The ideas that were developed by Gutmann and his colleagues were innovative and pathbreaking
for morphology and evolutionary biology. The large number of his morphological publications is indicative of the wide field
that was opened up by the concepts of constructional morphology. As some of his colleagues have suggested, constructional
morphology as an engineering approach to the study of organisms (i. e., engineering morphology) may replace the traditional
concepts of morphology and anatomy and provides the observational base for the historical reconstruction of evolutionary pathways.
Constructional morphology as a quasi-engineering approach can be the morphological pendant to the contemporary molecular approaches
to biology, as it can provide the necessary morphological basis for the interpretation of the results of molecular studies
in the light of evolution. 相似文献
95.
96.
Anton Weber 《Plant Systematics and Evolution》1987,157(3-4):187-199
Phyllagathis tuberculata
King and two closely allied new species,P. magnifica
A. Weber andP. stonei
A. Weber, are described and illustrated. Within the genus, these species form a distinct and isolated group which is restricted to Peninsular Malaysia.P. tuberculata occurs in Perak (probably confined to G. Bujang Melaka),P. magnifica andP. stonei are found in the mountains on the Pahang/Selangor border (Genting Highlands, Gombak valley). The distinctive characters of the three species are listed and some general information relating to inflorescence morphology, tubercle anatomy, fruit structure and seed dispersal is provided. 相似文献
97.
98.
Katharine W. Richards Earlene A. Rupert 《In vitro cellular & developmental biology. Plant》1980,16(11):925-931
Summary Pistils ofTrifolium repens L. andT. ambiguum Bieb. were cultured on an agar-based modified Murashige-Skoog medium. Pistils with and without accessory floral parts were
removed from flowers of selected clones ofT. repens, hand-pollinated under aseptic conditions, and planted on the medium. Pistils cultured without accessory floral parts showed
no evidence of fertilization after 2 weeks. However, 52% of thoseT. repens pistils cultured with calyx lobes and pedicels contained ovules with maturing embryos 12 days after in vitro cross-pollination.
Pistils fromT. ambiguum intraspecific cross-pollinations could not be cultured successfully under the same conditions; however, addition of various
combinations of auxin, cytokinin, and gibberellic acid enhanced embryo growth. Fertilization and partial embryo development
occurred in interspecific crosses betweenT. ambiguum andT. repens orT. hybridum only whenT. ambiguum was used as the pistillate parent. These results indicate that embryological development under in vitro conditions closely
parallels in situ development although growth regulator requirements may vary among species.
This work is Technical Contribution 1785 from the South Carolina Agricultural Experiment Station and was supported by SCAES-USDA
Cooperative State Research Agreement No. 616-15-65. 相似文献
99.
Intraspecific Variation in Cryptocaryon irritans 总被引:10,自引:0,他引:10
ABSTRACT. Intraspecific variation in the ciliate Cryptocaryon irritans was examined using sequences of the first internal transcribed spacer region (ITS-1) of ribosomal DNA (rDNA) combined with developmental and morphological characters. Amplified rDNA sequences consisting of 151 bases of the flanking 18 S and 5.8 S regions, and the entire ITS-1 region (169 or 170 bases), were determined and compared for 16 isolates of C. irritans from Australia, Israela and the USA. There was one variable base between isolates in the 18 S region nd 11 variables indicate that Australian C. irritans isolates from estuarine (Moreton Bay) and coral reef (Heron Island) environments are distinct. The Heron Island isolate was genetically closer to morphologically dissimilar isolates from Israel (1.8% divergence) and USA (2.3 % divergence) than it was to the Moreton Bay isolates. Three isolates maintained in our laboratory since February 1994 originated from the same source. During this time the sequence of the isolates from wild fish in Moreton Bay remained unchanged. These genetic differences indicate the existence of a founder effects in laboratorty populations of C. irritans . The genetic variation found here, combined with known morphological and developmental differences, is used to characterise four strains of C. irritans . 相似文献
100.
PASCAL NEIGE DIDIER MARCHAND BERNARD LAURIN 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1997,30(2):145-155
Ontogenetic and then heterochronic approaches are used here to analyze sexual differentiation within two well-known Jurassic dimorphic species. This analysis compares two ways of determining the relative biological age of ammonites, one using size (diameter) and the other the number of septa as a proxy of age. The shape standard is established from factor analysis of morphological and growth parameters. Size-age-shape relationships are analyzed on the basis of a new heterochronic representation. When diameter is used as a proxy of age, microconch morphs are globally considered to be progenetic compared with macroconch morphs. When size and age are determined separately and shape is included, (1) Ebrayiceras jactatum (microconch morph) has a shorter period of growth (progenesis) with acceleration of shape compared with its macroconch morph ( Morphoceras macrescens ), (2)( Cardioceras cordatum (microconch morph) has a shorter period of growth (progenesis) coupled with a slower rhythm of growth (dwarfism) compared with its macroconch morph. These findings emphasize the complex relationship between supposed sexual dimorphs in ammonites when size and age standards can be separated, as well as the need for an ontogenetic approach. 相似文献