Search results for "Ontogeny"

L'ontogenèse complexe du spatangue Echinocardium cordatum: Un test des standards des trajectoires hétérochroniques

1991

The growth of the spatangoid echinoid Echinocardium cordatum is described by using the three standards (size,shape and age) that are classicaly involved in analyses of heterochronies. A population from Normandy, including all the growth stages, allows an ontogenetic reference to be established, while comparisons are performed with adult samples from other localities (Brittany, Aquitaine, and New-Zealand). The morphology of E. cordatum is characterized by 23 measured parameters and 13 calculated indexes. The ontogenetic trajectory of the species is depicted from the measurements of the size increments, from the analysis of the shape changes, and from an estimate of age. An estimate of the ag…

Ontogenetic Habitat Selection by Hadwenius pontoporiae (Digenea: Campulidae) in the Intestine of Franciscanas (Cetacea)

1997

The linear habitat selection of 4 sequential maturity stages (1, 2, 3, and 4) of the trematode Hadwenius pontoporiae in the intestines of 26 South American dolphins Pontoporia blanvillei was investigated. The franciscana is a suitable host for H. pontoporiae because all 26 hosts were infected, the infrapopulations being composed mostly of gravid (stage 4) worms. Most trematodes were found in the first third of the intestine. The niches of the maturity stages decreased from stage 1 to 4. Gravid worms favored the most anterior part of the duodenum, whereas stages 1, 2, and 3 occurred more posteriorly in every host. The distributions of the maturity stages showed a narrow site fidelity and wer…

Polypeptide Markers Differentiating Juvenile and Adult Tissues in Chestnut

1993

Differences were observed between the polypeptide contents of in vitro shoot cultures derived from upper branches (adult material) and basal shoots (juvenile material) of the same chestnut tree. Cultures derived from mature crown growth yielded two polypeptide bands that were not afforded by cultures derived from juvenile basal shoots. Since all cultures were derived from the same tree the polypeptide differences appear to reflect the ontogenetic age of the starting material.

LACTATE DEHYDROGENASE ISOENZYMES IN THE NERVOUS TISSUE. IV. AN ONTOGENETIC STUDY ON THE RAT BRAIN.

1964

Regulation of cuticular hydrocarbon profile maturation by Drosophila tanning hormone, bursicon, and its interaction with desaturase activity

2016

International audience; Shortly after emergence the exoskeleton (cuticle) of adult insects is rapidly expanded, hardened (sclerotized), and pigmented (melanized). In parallel with this process, the oenocytes, which are large polyploid cells located below the abdominal epidermis, secrete onto the cuticle a cocktail of cuticular hydrocarbons (CHs) and waxes. These improve the waterproofing of the cuticle, and also provide important chemosensory and pheromonal cues linked with gender, age, and species differentiation. The hardening and pigmentation of the new cuticle are controlled by the neurohormone, bursicon, and its receptor, encoded by the DLGR2 receptor, rickets (rk); by contrast, little…

Evolution of Leaf Morphogenesis: Evidence from Developmental and Phylogenetic Data in Papaveraceae

1999

Variation of leaf morphology in Papaveraceae s.l. (including Fumariaceae and Pteridophyllum) has previously been shown to be related to developmental differences in the direction of segmentation and in blade‐petiole differentiation. Based on ontogenetic comparisons, we here distinguish polyternate, acropetal, basipetal‐pedate, basipetal‐pinnate, and divergent modes of dissection. In addition, undissected leaves occur in some taxa. Dissection modes can be grouped in two classes on the basis of blade‐petiole differentiation. Mapping of these morphogenetic traits on an independently obtained phylogenetic reconstruction reveals a high degree of homoplasy, indicating multiple evolutionary parall…

Astacins: proteases in development and tissue differentiation

2013

Capítulo en: Stöker, Walter; Brix, Klaudia (eds.). Proteases: structure and function. Wien: Springer, 2013

The ontogeny of the filter apparatus of anuran larvae (Amphibia, Anura)

1991

The pharynx ofBufo calamita, Rana temporaria andBombina variegata larvae (larval Types IV and III) changes considerably during the latter part of embryonic development. The entodermal regions between the visceral pockets flatten inward to form the anlagen of the filter plates. The ectoderm thrusts forward from the area of the persistent epidermal gills overlying the anlagen of the filter plates. The esophagus pushes dorsolaterally into the pharynx to give rise to the ciliary cushions. Comparison with the development ofXenopus laevis (larval Type I) reveals shared characters: (1) the filter plates are overlapped by the sensory layer of the epiderm and (2) the ciliary grooves are, like the ci…

Interannual to decadal variability of summer sea surface temperature in the Sea of Okhotsk recorded in the shell growth history of Stimpson's hard cl…

2017

Abstract Sclerochronological and shell stable oxygen isotopic analyses were conducted on live-caught specimens of Stimpson's hard clams, Mercenaria stimpsoni , from the southern Sea of Okhotsk, off northern Hokkaido, Japan. In this region, the main growing season of this species during early ontogeny (below the age of 12 years) lasts from mid-spring to mid-fall at sea surface temperatures (SST) between approximately 10 and 22 °C. Growth cessation begins between late fall and early spring at SST, below approximately 6 °C; however, shell growth was largely limited to the summer season later in life. Counting of annual increments indicated that this species had a relatively long life span of u…

The Oral Cavities of Central European Anuran Larvae (Amphibia)

1982

AbstractWith few additions (structures here called prenarial lobes, prenarial arena pustulations, prevalar pustulations), WASSERSUG'S ( 1976) terminology is adequate to describe the oral structures of Central European anuran larvae. The oral cavities of Bombina and Alytes (Discoglossidoidei) are very similar in structure. Based on oral anatomy Pelabates fuscus appears to occupy an intermediate position within the Anura and a basal position among the Ranoidea, which are morphilogical very heterogeneous in oral characters. This assessment is consistent with the findings of other authors working on the anatomy of the tadpole head. Extensive morphological diversity can be found even within the …