Trypanosoma (Herpetosoma) lewisi is a globally distributed rat trypanosome, currently considered as a zoonotic pathogen; however, a detailed understanding of the morphological events occurring during the cell cycle is lacking. This study aimed to investigate the cell cycle morphology and cleavage events of Trypanosoma lewisi (T. lewisi) during in vitro cultivation. By establishing in vitro cultivation of T. lewisi at 37°C, various cell morphologies and stages could be observed. We have provided a quantitative analysis of the morphological events during T. lewisi proliferation. We confirmed a generation time of 12.14 ± 0.79 hours, which is similar to that in vivo (12.21 ± 0.14 hours). We also found that there are two distinct cell cycles, with a two-way transformation connection in the developmental status of this parasite, which was contrasted with the previous model of multiple division patterns seen in T. lewisi. We quantified the timing of cell cycle phases (G1n, 0.56 U; Sn, 0.14 U; G2n, 0.16 U; M, 0.06 U; C, 0.08 U; G1k, 0.65 U; Sk, 0.10 U; G2k, 0.17 U; D, 0.03 U; A, 0.05 U) and their morphological characteristics, particularly with respect to the position of kinetoplast(s) and nucleus/nuclei. Interestingly, we found that both nuclear synthesis initiation and segregation in T. lewisi occurred prior to kinetoplast, different to the order of replication found in Trypanosoma brucei and Trypanosoma cruzi, implicating a distinct cell cycle control mechanism in T. lewisi. We characterized the morphological events during the T. lewisi cell cycle and presented evidence to support the existence of two distinct cell cycles with two-way transformation between them. These results provide insights into the differentiation and evolution of this parasite and its related species. 相似文献
The seasonal cycle of Picromerus bidens L. (Heteroptera: Pentatomidae) is usually considered to be univoltine with an obligatory winter egg diapause. Seasonal adaptations of the species were studied in the laboratory and in field experiments. When reared under short-day photoperiodic conditions (L12:D12 and L14:D10), all females began to lay eggs synchronously soon after their emergence. However, in the females reared under long-day conditions (L18:D6 and L20:D4) and outdoors in June–July, oviposition was significantly delayed. This delay in reproduction induced by photoperiodic conditions and then spontaneously terminated was considered to be aestivation. Egg batches laid by females in the laboratory and in the field were kept at 25 °C for two months. From 30.8 to 93.8% of batches contained eggs which hatched without cold treatment between day 14 and 60 after oviposition. The proportion of eggs hatched was 17.7 to 20.9% in the short-day regimes, while it was significantly less (5.7 to 6.0%) under long-day conditions. It is concluded that in some eggs diapause is of low intensity and that if under natural conditions the first batches had been laid at the end of June, nymphs would have hatched at least from some eggs during the same season even without cold treatment. Such untimely hatching would have resulted in the death of nymphs and adults unprepared for overwintering. A photoperiodic response which induces aestivation in the early emerging adults in June–August may prevent early oviposition and occurrence of a second generation and thus maintains univoltinism in P. bidens.相似文献
The effects of five diets (larvae of Galleria mellonella L., larvae of Spodoptera littoralis (Boisduval), eggs of Ephestia kuehniella Zeller, cysts of Artemia franciscana Kellogg and an artificial diet based on bovine meat) on development, survival and reproduction of two predatory stinkbugs,
Picromerus bidens L. and Podisus maculiventris (Say), were studied in the laboratory. Both species successfully completed immature development on the foods offered, except
for P. bidens on cysts of A. franciscana. Significant effects of diet on developmental duration were found in both species. Total developmental time from second instar
to adult ranged from 25.0 to 41.5 days and from 18.7 to 46.0 days in P. bidens and P. maculiventris, respectively. Nymphal survival of P. maculiventris was superior to that of P. bidens on all diets tested. Nymphal survival of P. maculiventris was greater than 92% on all diets except on A. franciscana cysts, yielding only 50% survival to adulthood. Survival of P. bidens fed on eggs of E. kuehniella was higher than that of conspecifics fed on caterpillar prey or artificial diet (89% on flour moth eggs vs. 68 and 80% on
G. mellonella and S. littoralis and only 50% on meat diet). Fresh weight of newly emerged females of both pentatomids was affected by the diet offered to
the predators during their nymphal stage. Females of P. maculiventris produced viable eggs on all diets except on cysts of A. franciscana and had mean fecundities of 691, 436, 608 and 344 eggs per female on S. littoralis, G. mellonella, E. kuehniella eggs and the meat diet, respectively. Females of P. bidens laid eggs only on live prey with mean fecundities of 94 and 38 eggs per female on S. littoralis and G. mellonella, respectively. The results indicate a lower nutritional plasticity of P. bidens as compared with P. maculiventris.
An erratum to this article can be found at 相似文献
Trypanosoma lewisi and Trypanosoma musculi were collected from immunosuppressed infected hosts and extracted with phosphate buffered saline. Antisera were obtained from rats repeatedly infected with T. lewisi or mice repeatedly infected with T. musculi. Cellular antigens (CAg) present in the extracts of the parasites were analyzed by microimmunodiffusion (MID), crossed immunoelectrophoresis (CIE) and tandem crossed immunoelectrophoresis (TCIE). Trypanosome extracts were absorbed with the heterologous hyperimmune antisera to examine shared and unique antigens of the parasites.
Extracts of T. lewisi formed four precipitin lines when reacted with hyperimmune rat antiserum and three precipitin lines were detected by mouse anti-T. musculi serum in MID analyses. T. musculi extract formed two precipitin lines with mouse hyperimmune serum and two precipitin lines with rat anti-T. lewisi serum in the MID tests. When T. lewisi was reacted with the homologous hyperimmune rat antiserum in CIE, 14 precipitin peaks developed, while T. musculi extract formed eight peaks with homologous mouse hyperimmune serum. Seven precipitin peaks developed when T. lewisi extract was reacted with the mouse antiserum and T. musculi extract formed eight peaks during its electrophoretic migration into rat anti-T lewisi serum. TCIE clearly showed that five T. lewisi CAg could not be detected in the T. musculi extract by the rat antiserum, while mouse anti-T. musculi serum formed six precipitin peaks with the T. lewisi extract and seven peaks with the homologous extract. One of the CAg present in the T. musculi extract was not found in the T. lewisi extract. Absorptions of the extracts with heterologous antisera and subsequent CIE against the homologous antisera indicated three of the CAg of T. lewisi were not shared by T. musculi, while a single antigen of T. musculi was not detected in T. lewisi. Although concentrations of antibodies in each of the antisera and CAg in the parasite extracts were not equivalent, the data indicated that a minimum of eight CAg are shared by these rodent trypanosomes and at least three antigens appeared to be unique to T. lewisi and a single antigen to T. musculi. 相似文献
The ecological features and geographic distribution of Anopheles beklemishevi have not been studied extensively. These studies are important in connection with the validity of the ‘Anopheles lewisi’ taxon. The materials were collected in Russia and Kazakhstan from 1973 to 2012, and species identity was defined by cytogenetic analysis of polytene chromosomes of larvae and adult females. A total of 7,896 specimens from 34 geographic locations was included in the analysis. It was established that An. beklemishevi is distributed from the east coast of the Baltic Sea to the basin of the Lena River, and from the forest‐tundra zone to the Altai and Sayan Mountain systems. This species is exophilic and is confined to high and/or swampy terrains found in the zone of conifer and mixed forests. The frequency of An. beklemishevi in the southwestern area, where it is sympatric with An. messeae s.l., has significantly decreased over the past decades. The results of the study indirectly suggest that An. beklemishevi does not play a significant role as a vector of malaria. It is highly improbable that An. beklemishevi and An. lewisi are the same species. Changes in the proportions of the species of the Maculipennis complex, as well as a shift of their ranges, will significantly impact the epidemiology of malaria over large areas of northern Eurasia. 相似文献
The Palaearctic stinkbug Picromerus bidens L. (Heteroptera: Pentatomidae) has been considered as a potential biocontrol agent of several defoliator pests in various
agricultural and forest ecosystems. It may therefore be a valuable alternative for the Nearctic pentatomid Podisus maculiventris (Say) (Heteroptera: Pentatomidae), the augmentative use of which has largely been abandoned in Europe given its possible
environmental impact as an exotic polyphagous predator. However, no study has yet documented the impact of insecticides on
P. bidens, which is essential to evaluate the possible combination of this predatory pentatomid with current insecticide applications
in integrated pest management (IPM) programmes. This study reports on laboratory experiments investigating the susceptibility
of P. bidens to five insecticides with different modes of action: the pyrethroid deltamethrin, the diacylhydrazine methoxyfenozide, the
juvenile hormone mimic pyriproxyfen, the spinosyn spinosad, and the neonicotinoid imidacloprid, all of which are used to control
defoliator pests. Fourth-instar nymphs and female adults of the predator were exposed to formulated materials of the insecticides
by residual contact. Methoxyfenozide and spinosad did not cause significant mortality to 4th instars and female adults of
P. bidens. In contrast, deltamethrin and imidacloprid were harmful to nymphs and adults of the predator, with LC50 values ranging between 1.5 and 9.9 mg a.i./l. Pyriproxyfen was toxic to 4th instars with an LC50 value of 13.9 mg a.i./l but did not affect female adults. Reproduction and longevity of P. bidens were not adversely affected when the predator was exposed to field concentrations of spinosad, methoxyfenozide, or pyriproxyfen,
or sublethal concentrations (around LC10) of deltamethrin and imidacloprid. The results from residual contact experiments suggest that methoxyfenozide, spinosad,
and to a lesser extent, pyriproxyfen may be compatible with P. bidens in an IPM programme. Further experiments assessing food chain toxicity of these compounds should offer a more complete picture
of their selectivity. 相似文献