摘要:

Seasonal changes in gonadal morphology, secondary sexual characters, and plasma sex steroids were studied in male and femaleBombina pachypusfrom southern Italy. In this species, frogs are active and breed from May to September. During the long breeding season, sperm were always present in the testes. However, the testes did not always exhibit all stages of spermatogene‐sis. In July, spermatogenesis did not exceed the stage of sperma‐tocyte I, whereas in August it included all stages. It is possible that males use sperm originating from the preceding fall for the earliest spring matings. Throughout the breeding season, females showed many follicles in advanced or complete vitellogenesis and many atretic vitellogenic follicles. Postovulatory follicles, if any, were rare. Females laid few eggs at each oviposition. Concerning male sex steroids, testosterone was at comparable levels from May to September, and it markedly decreased in October. In females, wide variations in plasma estradiol and progesterone levels were observed only in individuals with postovulatory follicles. Emphasis is given to the prolonged and opportunistic reproductive activity of this species.

ISSN:1125-0003    

DOI:10.1080/11250009809386770

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A different reactivity of the demospongeChondrosia reniformispinacoderm with regard to crystalline and amorphous silica is described. Following the crystalline quartz particle settlement, the pinacoderm breaks and exopinacocytes contract to form a rim around this foreign material that becomes gradually incorporated. Instead, amorphous opaline spicules elicit a motile response of exopinacocytes. At the onset of this process they lay a thin homogeneous matrix on the spicule, while afterwards several exopinacocytes join together forming a cellular coat covering the spicule. The sinking of both kinds of foreign material is allowed by the malleable organization of the collagenous ectosome. The effect of different silica crystalline forms on sponge cells is discussed by considering similar phenomena in other animals.

ISSN:1125-0003    

DOI:10.1080/11250009809386771

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Morphological and functional studies were performed on hemocytes from young and adultMytilus galloprovincialis.The results obtained suggest that only one cell type in two different stages, young or old, is present, consistently with the Mix's one‐cell‐type model. However, both young and old hemocytes appear capable of carrying out similar functions and express common signal molecules; thus, their differences in cytology and number appear to be due to cellular aging.

ISSN:1125-0003    

DOI:10.1080/11250009809386772

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Among the many circumstances in which apoptosis plays a role, there is the reduction of cell number during regression of organ hyperplasia due to mitogens. The present study investigates whether a single intravenous injection of lead nitrate to rat could exert a proliferative stimulus in a number of organs (i.e., liver, kidney, spleen, intestine, stomach, brain, and heart), and, as well, looks at the fate of the cells generated by the mitogenic stimulus. Microscopic analysis revealed that liver, spleen, and kidney are affected by metal intoxication, while intestine, stomach, brain, and heart are partially or totally resistent to the treatment. Proliferation of the hepatic, renal, and splenic tissues was observed within a few days of treatment, followed by regression of hyperplasia due to apoptosis. The appearance of apoptotic cells was never observed during proliferation or at restoration of the organ mass. In the tissue sections, apoptotic cells were observed both in the extracellular spaces and inside the cytoplasm of the healthy ones, as a result of their phagocytosis.

ISSN:1125-0003    

DOI:10.1080/11250009809386773

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An electrophysiological investigation was performed to analyse activity recorded in response to stimulation with concentrated and diluted solutions of NaCl, sucrose, formamidine acetate, and sodium acetate from labellar chemosensilla of the dipteranProtophormia terraenovae.A computerized analysis of this activity led to the finding of four kinds of spikes (A, B, C, and D) which differed in their wave forms. The forms of spikes A, B, and C are described in the literature as being evoked by activation of the specific salt, water, and sugar neurones respectively. The fourth type of spike (D) recorded in response to formamidine acetate and sodium acetate is probably generated by a fourth chemosen‐sorial cell that has not yet been defined functionally. These two acetates evoke activities that are equivalent both in spike frequency and time distribution even at low concentrations. The results suggest that the acetate ion in the blowfly effectively stimulates the fourth chemosensory neuron present in the sensillum. The activation appears to be involved in signalling acidity to the insect.

ISSN:1125-0003    

DOI:10.1080/11250009809386774

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The presence of taste and olfactory chemosensilla is demonstrated by using both morphological and electrophysiological techniques on antennae ofOpius concolor,a parasitoid of tephritid larvae. Observation under the Scanning Electron Microscope revealed the presence of large sensilla trichodea with an apical pore, and of flat plates (sensilla placodea) extending almost the entire length of each antennomere. By means of currently used electrophysiological techniques, it was possible to record both the gustatory activity generated by sensilla trichodea following contact with KC1 100 mM and sucrose 100 mM solutions, and olfactory activity probably generated by sensilla placodea in response to volatile stimuli. The analysis of gustatory activity showed that each sensillum trichodeum consisted of at least three chemosensory units. This supports the assumption that inO. concolorsingle sensilla may, by providing different spike discharge patterns, which depend on the quality and intensity of the stimulus, provide the CNS with adequate information for peripheral discrimination among stimulating chemicals. Study of the sensory input ofO. concolorwith electrophysiological techniques may be of great scientific importance for possible applications in biocontrol of the olive fly.

ISSN:1125-0003    

DOI:10.1080/11250009809386775

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Two new species ofTethya(Porifera Demospongiae),T. irregularisandT. variansare described.T. irregularis,characterized by megasters with markedly reduced or abnormal rays, comes from Lanzarote (Canary Islands) whileT. varians,with very heteroge‐nous megasters in size and shape, is from Isla do Sal (Cape Verde Islands).

ISSN:1125-0003    

DOI:10.1080/11250009809386776

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Most species ofUrodasysbear a clearly structured cuticular stylet in the caudal organ, that constitutes a powerful diagnostic feature. On the basis of the morphology of this stylet, two new species,Urodasys acanthostylisandU. uncinostylis,are described.Urodasys acanthostylisis diagnosed by a stylet with the tubular portion clearly bent at a slightly obtuse angle,U. uncinostylisby a stylet with the tubular portion which develops in about one and a half coils. The former was found along the Apulian coast (southern Italy) and in Malta, and the latter at the Maldives.

ISSN:1125-0003    

DOI:10.1080/11250009809386777

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Three species of the genusAcarochelopodiawere found at different places along the Italian coastline:A. cuneiferain Tuscany and Apulia,A. delamareiin Tuscany, andA. tarentinain Apulia.A. tarentinais new to science whileA. cuneiferais new to the Mediterranean.

ISSN:1125-0003    

DOI:10.1080/11250009809386778

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Otiorhynchus (Eunihus) praetutiorumn. sp. from central Italy is described. The new species, apparently limited to the winter snow valleys of the top of the Laga Massif, is related with Carpathian, Transylvanian, and Alpine species ofO. (Eunihus)Reitter, 1912 (status revised), here revived from synonymy with O.(Nihus)Reitter, 1912.Otiorhynchus praetutiorumis quite different fromO. (Eunihus) abnizzensisStierlin, 1898, also found in the Apennines, which is instead closely related to theO. (Eunihus)species from the Balkans and Anatolia, all living in dry high‐altitude pastureland.

ISSN:1125-0003    

DOI:10.1080/11250009809386779

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor