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Title:Ultrastrukturne spremembe celic srednjega črevesa med prezimovanjem velikega jamskega pajka, Meta menardi (Latreille 1804) (Araneae, Tetragnathidae), v naravnih habitatih
Authors:ID Weiland, Nina (Author)
ID Lipovšek, Saška (Mentor) More about this mentor... New window
ID Novak, Anton (Comentor)
Files:.pdf MAG_Weiland_Nina_2017.pdf (4,91 MB)
MD5: E36A913CE270C421AC801EA3C0F04DBA
 
Language:Slovenian
Work type:Master's thesis/paper
Typology:2.09 - Master's Thesis
Organization:FNM - Faculty of Natural Sciences and Mathematics
Abstract:Meta menardi je troglofilna vrsta. Večino življenjskega cikla preživi v podzemeljskih habitatih. V svojem življenjskem ciklu nima programiranega prezimovanja, kar pomeni, da se pozimi priložnostno prehranjuje. Ob nedostopnosti plena in posledičnem stradanju v celicah potečejo procesi, značilni za vrste s programiranim prezimovanjem, ki se pozimi ne prehranjujejo. S svetlobno in transmisijsko elektronsko mikroskopijo smo proučili strukturo in ultrastrukturo divertiklov srednjega črevesa M. menardi med prezimovanjem v naravnih habitatih. Samce in samice M. menardi smo nabrali v različnih obdobjih prezimovanja – na začetku (november), na sredi (januar) in ob koncu prezimovanja (marec). Zanimale so nas spremembe v strukturi in ultrastrukturi pri obeh spolih, spreminjanje količine založnih snovi, značilnosti sferitov in pojav avtofagnih struktur, ki odražajo trajanje stradanja med prezimovanjem. Epitel divertiklov srednjega črevesa je bil zgrajen iz prebavnih, sekrecijskih in založnih celic. V strukturi in ultrastrukturi med spoloma ni bilo razlik. Med prezimovanjem so se v epitelnih celicah divertiklov pojavile spremembe, značilne za stradanje. Količina založnih snovi (glikogena in lipidov) se je zmanjšala. Sferiti so imeli med prezimovanjem vse več elektronsko svetlejših, izpraznjenih plasti. Število avtofagnih struktur, stopnja vakuolizacije citoplazme in poraba materiala iz vakuol so se povečali. Ultrastrukturne značilnosti, ki so odraz stradanja med prezimovanjem, so pri M. menardi posledica pomanjkanja in nedostopnosti plena, ki prezimuje v jamah. Nutriente in energijo za vzdrževanje različnih fizioloških procesov, potrebnih za preživetje med stradanjem, so pajki pridobivali s porabo energijsko bogatih založnih snovi, iz mineralnih in organskih sestavin sferitov, z razgradnjo celičnih sestavin v procesu avtofagije in intenzivne vakuolizacije ter priložnostno s prebavo ujetega plena. Ob koncu prezimovanja so se pri eni samici v tkivu z značilnostmi stradanja pojavile velike, elektronsko temne prebavne vakuole, z lipidnimi kapljami, kar je dokaz, da je samica ob koncu prezimovanja ujela plen. Ujetje plena je najverjetneje sovpadlo z zaključkom prezimovanja nekaterih nevretenčarjev v jami in posledično migracijo določenega plena iz jame.
Keywords:avtofagija, prezimovanje, sferiti, srednje črevo, stradanje, ultrastruktura, založne snovi
Place of publishing:Maribor
Publisher:[N. Weiland]
Year of publishing:2017
PID:20.500.12556/DKUM-65298 New window
UDC:591.132.5:595.44(043.2)
COBISS.SI-ID:23061512 New window
NUK URN:URN:SI:UM:DK:MKITFGXL
Publication date in DKUM:08.05.2017
Views:1641
Downloads:122
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:FNM
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Secondary language

Language:English
Title:Ultrastructural changes of the midgut cells during overwintering of Meta menardi (Latreille 1804) (Araneae, Tetragnathidae) in natural habitats
Abstract:Meta menardi is a troglophile species. They spend most of their life cycle in hypogean habitats. There is no programmed overwintering in the life cycle of M. menardi, which means that they can occasionally feed during the wintertime. In the absence of prey, the spiders starve and in the epithelial cells of the midgut diverticula appear processes, typical of species with programmed overwintering, i. e., programmed starvation in winter. Using the light and transmission electron microscopy we studied structure and ultrastructure of the epithelial cells of midgut diverticula in M. menardi during overwintering in natural habitats. Males and females were collected in different time frames of overwintering – at the beginning (November), in the middle (January) and at the end (March) of overwintering. The aim of this study was to investigate structural and ultrastructural changes in both sexes, changes in quantity of reserve substances, ultrastructure of spherites and occurrence of autophagic structures, which progressive changes reflect the duration of starvation during overwintering. The midgut epithelium was constituted of digestive, secretory and reserve cells. There were no differences in the structure and ultrastructure in the midgut diverticula epithelium between the sexes. During overwintering, in the midgut diverticula epithelial cells, changes typical of starvation occurred. The quantities of reserve substances (glycogen and lipids) diminished. During overwintering spherites became gradually more electron lucent, since the concentric layers were exploited. The abundance of the autophagic structures, the degree of cytoplasm vacuolization and the use of the cytoplasmic material increased. Ultrastructural features of the M. menardi midgut epithelium reflected processes typical of starvation during overwintering. These features are the consequence of absence and unavailability of prey in caves during the wintertime. All M. menardi obtained nutrients and energy for maintenance of different physiological processes, indispensable for survival during the starvation period, from different sources. Nutrients and energy were provided from lipid and glycogen reserves, mineral and organic compounds from spherites and degradation of cytoplasmic components in the processes of autophagy and intensive vacuolization. Occasionally, some individuals captured and digested prey. Consequently, at the end of overwintering, in a female at the same time characteristics typical of starvation, and large, electron dense digestive vacuoles with lipid droplets occurred. This case of prey capture probably coincided with the end of overwintering of some invertebrates in caves, and their migration out of the cave.
Keywords:autophagy, midgut, overwintering, reserve substances, spherites, starvation, ultrastructure


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