Alterations in metabolic activity of Cysticercus fasciolaris on some anthelmintic treatments.

Effect of candidate compounds 81-470 i.e. methyl [5[4-(2-pyridinyl)-1-piperazinyl]carbonyl]-1H-benzimidazole-2-yl]- carbamate and 86-162 i.e. methyl-5(6)-(alpha-hydroxyphenyl methyl) benzimidazole-2-carbamate along with reference drugs mebendazole and praziquantel on energy metabolism of C. fasciolaris recovered from rats treated with single dose of 500 mg/kg, ip was investigated. All the drugs significantly lowered the rate of uptake of glucose and alanine by the parasite. Suppression in the formation of lactate, the major end-product, was also noticed. Nonetheless the ratio of lactate produced versus the substrates consumed was not substantially affected. The recovered cysticerci also possessed less glycogen and ATP compared to the normal parasites. Although the effects exerted by the drugs were of the identical nature, they significantly differed in the magnitude of their action. Mebendazole followed by praziquantel maximally affected all the above metabolic activities while 86-162 proved to be the weakest in action. The results suggest that the examined drugs exert their chemotherapeutic activity by interfering with uptake of glucose and alanine but do not significantly alter their catabolism.     

The occurrence of the larval cestode Cysticercus fasciolaris in rodent populations from the Cuxtal ecological reserve, Yucatan, Mexico

Cysticercus fasciolaris is the larval stage of the cestode Taenia taeniaeformis, whose definitive hosts are mainly cats. This larval stage uses a wide variety of small rodents, and occasionally birds and humans, as intermediate hosts. In the Yucatan, there are no reports of the presence of this cestode in animal populations. The aim of this study was to evaluate the occurrence of C. fasciolaris in rodent populations from the Cuxtal ecological reserve, Yucatan, Mexico. Trapping of rodents was conducted from October 2009 to April 2010 in 40 households in Molas, in which Sherman traps were placed both inside and outside backyards. Rodents were dissected to inspect the liver for the presence of the worm. To determine risk factors associated with infection, univariate analysis was performed using sex, age, species, trapping site, and season as independent variables. Variables with a P value < 0.2 were analysed using a logistic regression model. In this study, 411 individuals of six rodent species were trapped; Mus musculus was the most abundant (78%), followed by Rattus rattus (13%) and the wild species Peromyscus yucatanicus, Ototylomys phyllotis, Heteromys gaumeri and Reithrodontomys gracilis (9%). Only 7.5% (n?=?31) of M. musculus and R. rattus were infected with C. fasciolaris (demonstrated by the presence of liver cysts) with a prevalence of 9.0% and 3.5%, respectively. Both adults and male mice were 4.33 and 3.46 (OR values) times more likely to have C. fasciolaris than juveniles and females respectively. We can conclude that in the Cuxtal Reserve, Yucatan, Mexico, the prevalence of C. fasciolaris is higher in M. musculus, and that adult males had a higher probability of infection. Wild species, mainly P. yucatanicus, were not found to be infected with the cestode, but its presence in the backyards of households could result in a potential risk of acquiring this infection.     

The surface coat of chylomicrons: electron microscopy

Electron microscope studies were performed on thoracic duct lymph and on washed chylomicrons from dogs fed corn oil. High-resolution electron micrographs showed the presence of a surface coat that differed from the core material and did not resemble a plasma membrane. This was true for both chylomicrons in whole lymph and those that had been subjected to repeated washing. Apparently, the chylomicrons, while passing from the intracellular to the extracellular space, do not acquire their surface coat from pinched off cellular membrane.     

The carbohydrate content of control and virus-transformed cells

The levels of carbohydrates were measured in cells before and after transformation with DNA and RNA-containing oncogenic virus. The most consistent finding was a markedly lower content of L-fucose in all transformed cells relative to their normal counterpart. The cell pellet from a line of Chinese hamster cells transformed with polyoma or SV-40 viruses showed a marked decrease in the level of carbohydrates. However, when the carbohydrate levels were calculated for the whole system (cells plus wash) the transformed cells except for L-fucose had almost the same amount of carbohydrate as the controls. The levels of various carbohydrates in cells transformed by Rous sarcoma virus were the same or were elevated above the controls. Here consideration of the washes did not alter the results. Possible explanations for the results and causes of error in these comparative studies are discussed.     

The crater defect in boar spermatozoa: A correlative study with transmission electron microscopy,scanning electron microscopy,and light microscopy

Nuclear vacuoles resembling the “crater defect” described in bull spermatozoa were observed in 14 boars. Both the incidence of the defect and semen quality were monitored with phase contrast microscopy over a three-month period. The percentages of cratered spermatozoa varied widely both among boars and in ejaculates from the same boar taken on different days. The presence of cratered spermatozoa at a level of 5% or more appeared to be associated with low semen quality. The defect was studied with scanning and transmission electron microscopy and was found to consist of nuclear invaginations, about 0.5 μm in diameter, containing some scanty amorphous electron-dense material. In boars showing a high incidence of spermatozoa with crater defects, abnormalities of the acrosome and perforatorium were common.     

Bridging fluorescence microscopy and electron microscopy

Development of new fluorescent probes and fluorescence microscopes has led to new ways to study cell biology. With the emergence of specialized microscopy units at most universities and research centers, the use of these techniques is well within reach for a broad research community. A major breakthrough in fluorescence microscopy in biology is the ability to follow specific targets on or in living cells, revealing dynamic localization and/or function of target molecules. One of the inherent limitations of fluorescence microscopy is the resolution. Several efforts are undertaken to overcome this limit. The traditional and most well-known way to achieve higher resolution imaging is by electron microscopy. Moreover, electron microscopy reveals organelles, membranes, macromolecules, and thus aids in the understanding of cellular complexity and localization of molecules of interest in relation to other structures. With the new probe development, a solid bridge between fluorescence microscopy and electron microscopy is being built, even leading to correlative imaging. This connection provides several benefits, both scientifically as well as practically. Here, I summarize recent developments in bridging microscopy.