Search

The use of complementary visualization and measurement techniques allowed accurate description and quantification of changes in the intestinal mucosal architecture and provided a comprehensive outlook on the dynamics of remodeling and maturation processes of the mucosal layer taking place in the small intestine of piglets from birth to weaning. The aim of the study was to examine the early postnatal development of the small intestine in pigs. Three techniques were used: scanning electron microscopy (measurements ofvillus density and shape, height ofenterocytes and microvilli, cell exfoliation, and location of extrusion zones), optical microscopy (cross section, measurement of structures: villus length and width; crypt depth; mucosal thickness), and confocal microscopy (cell localization, apoptosis, exfoliation and migration). The postnatal development ofthe mucosal layer ofthe small intestine was reflected in changes in the density, length, width, and shape of villi, crypt depth, replacement of enterocyte population, and arrangement. The presence of deep transverse furrows on villus corpus and vacuolated fetal-type enterocytes in the mucosal layer of the small intestine, which are able to engulf large amounts of colostrum shortly after birth, appears to play an important role in the observed phenomenon of straightening of the villus height and increasing of the villus diameter shortly after birth. We hypothesized that the intestinal mucosal layer is compressed before birth and ready to unfold within a short time after birth.

Additonal morphological data are provided for Steinernema jollieti Spiridonov, KrasomilOsterfeld, Moens, 2004. A light and scanning electron microscopy were used to particularize taxonomically important characters missing in the first decsription. The GS% and SW% indices are provided for males. The distribution of genital papillae on male tail is illustrated with SEM images. Structure of female tail and vulvar area are decsribed for females of the first and second generation. The relationships of S. jollieti with other steinernematid feltiae/kraussei group species are discussed.

Celem badań była charakterystyka nicieni porażających pędraki chrabąszcza Melolontha sp. w warunkach naturalnych. Pędraki chrabąszcza były zebrane na terenie nadleśnictw Krasnystaw, Kozienice, Opoczno i Brzeziny, na powierzchniach różniących się warunkami świetlnymi, wilgotnościowymi i temperaturowymi. Identyfikację gatunków przeprowadzono metodą sekwencjonowania fragmentów DNA (deoxyribonucleic acid) oraz metodami morfologicznymi przy zastosowaniu skaningowego mikroskopu elektronowego i mikroskopu optycznego z kontrastem interferencyjno-różnicowym. Uzyskane wyniki wykazały, że pędraki były porażone przez Diplogasteroides magnus oraz Koerneria sp. i Rhabditis sp. Większość zainfekowanych przez nicienie pędraków została zebrana na powierzchniach zadrzewionych, czyli tam, gdzie powierzchnia gleby była dobrze ocieniona, a wilgotność najwyższa. The main aim of the research was characterization of nematode species isolated from Melolontha sp. larvae. European cockchafer grubs were collected from the forest territory of Krasnystaw, Kozienice, Opoczno, Brzeziny, from areas with different light conditions, humidity and temperatures. The isolated nematodes were described based on light and scanning electron microscopy, supplemented with SSU rDNA (ribosomal deoxyribonucleic acid) sequence data. The obtained results revealed that grubs were infected by the following nematode species: Diplogasteroides magnus, Koerneria sp. and Rhabditis sp. Most of the grubs infected by nematodes were collected on tree-covered areas, where the surface was shadowed and humidity was the highest.

Experiments done and presented below aimed at proving that applied species and Polish strains of entomopathogenic nematodes (EPNs) can be used to reduce the number of Melolontha melolontha. Invasive larvae of Steinernema arenarium Bys, S. arenarium Lub, S. feltiae Rap, Heterorhabditis bacteriophora Sie, H. megidis Pla, H. megidis Lub i H. megidis Pla, H. megidis C3 were used in the experiments as biocontrol agents against the larvae L1, L2 and L3 of M. melolontha. The experiments were done at 20°C, in 25 ml boxes filled with pasteurized (3 h at 70°) and air-dried soil. Pathogen doses were 100 IJ/insect. The result showed that susceptibility of M. melolontha to EPNs depends on the insect's developmental stage. Larvae L1 were the most susceptible. S. arenarium Bys and H. megidis strains were more effective in infecting M. melolontha larvae than S. feltiae Rap and H. bacteriohora Sie.

The unique feature of enterocytes in newborn mammals is the presence of an apical canalicular system (ACS) leading to production of large vacuoles, important for colostral macromolecule uptake. The vacuolated fetal-type enterocytes (VFE) enable transfer of colostral and milk proteins from the intestinal lumen across the epithelium without loosing their biological activity. First VFE are observed in the pig and lamb fetuses in the second trimester of pregnancy, located at the upper part of villi in the proximal region of the fetal small intestine and subsequently in the middle and distal regions. After birth the VFE are replaced with enterocytes lacking ACS. The present study aimed to investigate the depletion of VFE in the small intestine in the sow reared pig neonates during the first postnatal weeks using scanning electron microscopy (SEM). The SEM analysis demonstrated the gradual disappearance of vacuolated enterocytes in time. VFE remained in the jejunum for a few days after birth, whereas in the duodenum single VFE were present only at birth. In the proximal jejunum, the VFE were localized in the upper part of the villi, and disappeared until the day 3 of life. VFE were present in the mid and distal jejunum, and diminished gradually until day 14 of life. By the day 21 of life, the vacuolated cells were not observed neither in the jejunum nor ileum. In conclusion, morphology analysis of pig small intestinal mucosa suggests that replacement of fetal type vacuolated enterocytes is resumed within 21 days after birth. KBN

The purpose of the present studies was to evaluate the susceptibility of Cameraria ohridella larvae to infection by entomopathogenic nematodes Steinernema sp. and Heterorhabditis sp. in laboratory conditions. The experiments were done at the temperatures 20 ◦C and 25 ◦C with the use of three doses of the pathogen, namely 5, 25 and 50 nematodes/insect. The results showed that Cameraria ohridella larvae were susceptible to infection by entomopathogenic nematodes. Out of two strains of entomopathogenic nematodes used in the studies, the one that was more effective in infecting Cameraria ohridella at the temperature 20 ◦C was Steinernema sp., while at the temperature of 25 ◦C Heterorhabditis sp. infected the insects more intensively. Results of the experiments showed that with lower doses of invasive larvae of nematodes (5 larvae/insect, 25 larvae/insect) Steinernema sp. PIS81 was a more pathogenic strain towards Cameraria ohridella as compared to Heterorhabditis sp. PIH81. Prezentowane badania miały na celu ocenę podatności larw Cameraria ohridella na porażanie przez nicienie entomopatogeniczne Steinernema sp. i Heterorhabditis sp. w warunkach laboratoryjnych. Doświadczenia przeprowadzono w temperaturach 20◦C i 25◦C oraz przy zastosowaniu trzech dawek patogena: 5, 25 i 50 nicieni/owad. Wyniki doświadczeń wykazały, że larwy Cameraria ohridella są podatne na porażenie przez nicienie entomopatogeniczne. Z dwóch wykorzystanych do badań szczepów nicieni entomopatogennych, szczepem efektywniej porażającym larwy Cameraria ohridella w temperaturze 20◦C był Steinernema sp., natomiast w temperaturze 25◦C z wyższą intensywnością porażał owady Heterorhabditis sp. Wyniki prezentowanych doświadczeń wykazały, że przy niskich dawkach larw inwazyjnych nicieni (5 larw/owad, 25 larw/owad) bardziej patogennym szczepem w stosunku do Cameraria ohridella jest Steinernema sp. PlS81 niż Heterorhabditis sp. PlH81.

Studies were conducted on the morphology of infective larvae Heterorhabditis bacteriophora using a scanning electron microscopy. The purpose of the studies was to point to the morphological and morphometric characters of infective larvae of entomogenous nematodes that are useful in taxonomy and species identification. It was found out that the studies using SEM make it possible to analyze the morphological characters unvisible in an optic microscope. Morphometric properties can also be examined in SEM, and since the measurements are very accurate they can be applied in taxonomic studies and in species identification. The preparation of the material for the studies in SEM and their performance is neither more labour-consuming nor more tiresome than in optic microscopy. Przeprowadzono badania nad morfologią larw inwazyjnych Heterorhabditis bacteriophora z wykorzystaniem skaningowego mikroskopu elektronowego. Celem badań było wskazanie użytecznych w taksonomii i identyfikacji gatunku cech morfologicznych i morfometrycznych larw inwazyjnych entomopatogenicznych nicieni. Stwierdzono, że badania przy użyciu SEM pozwalają analizować cechy morfologiczne, które nie są widoczne w mikroskopie optycznym. Cechy morfometryczne także mogą być badane w SEM, a dokonane pomiary są bardzo dokładne i możliwe wykorzystania w badaniach taksonomicznych i identyfikacji gatunku. Przygotowanie materiału do badań w SEM oraz ich prowadzenie nie jest bardziej pracochłonne i uciążliwe niż w mikroskopii optycznej.