大劣按蚊四龄幼虫吞食四种按蚊幼虫的实验室观察

大劣按蚊四龄幼虫会吞食其它按蚊的一龄幼虫,在文献中未见有详细报道,在按蚊饲养中,我们对大劣按蚊吞食按蚊幼虫的情况作了较细致的观察,现报道如下。1 材料和方法大劣按蚊(Ancpheles dirus)采自海南,驯化成功后我所引入饲养;中华按蚊(An.sinensis)系1987年采自思茅城郊,实验室驯化品系;嗜人按蚊(An.anthropophagus)由贵阳     

大劣按蚊不同时期游离氨基酸的变化

大劣按蚊幼虫期有28种氨基酸,β-丙氨酸含量最高;蛹期有27种氨基酸,雄蛹氨基酸总量比雌蛹高,其中羟脯氨酸、谷氨酸、谷氨酰胺、酪氮酸、β-丙氨酸,精氨酸含量较高;雄蚊有28种、雌蚊有27种氨基酸,雄蚊氨基酸总量比雌蚊高,其中羟脯氨酸、谷氨酰胺、脯氨酸、丙氨酸、半胱氨酸、酪氨酸、组氨酸、精氨酸含量较高。结果表明:同一种昆虫,不同时期、雌、雄的氨基酸含量和比例有差异。     

大劣按蚊成虫在低温下的活力

大劣按蚊成虫在低温下的活力宋宗臣重庆第三军医大学寄生虫学教研室６３００３８我国海南省的大劣按蚊是热带蚊种。该蚊在实验室自然交配繁殖种群建立成功后,已对其在最适温度（２６±２℃）条件下的交配、吸血及产卵等习性进行了较系统的研究￣［１．２．３］,但对在低...     

大劣按蚊生殖营养周期的实验室观察

本文观察大劣按蚊的生殖营养周期。在实验条件下每只雌蚊一生平均产卵326.92个,其中有2只产卵900个以上,雌蚊寿命可达61天,有2只雌蚊吸血9次,完成8个生殖营养周期。     

大劣按蚊卵保存在不同温度下的活力研究

用高湿法储存大劣按蚊卵,在29±1℃储存8和13天,孵化率分别为83.70±7.97％和6.58±4.48％;化蛹率分别为36.55±12.53％和1.23±0.88％。在24±1℃储存15和20天,孵化率分别为54.13±4.07％和27.23±4.53％:化蛹率分别39.17±4.96％和13.17±2.30％。在15±3℃储存20和30天,孵化率分别为80.69±2.24％和62.50±1.42％;化蛹率分别为39.83±3.18％和18.75±1.29％。在7±1℃储存11天,孵化率为0。结果表明:以上几种温度中,以15±3℃保存大劣按蚊卵活力最好。     

大劣按蚊吸血活动与交配受精的关系

大劣按蚊Anophelos dirus是我国及东南亚地区的重要传疟媒介。研究表明成蚊羽化后,在未喂血的情况下,可有较高的交配受精率。在同一蚊笼,吸血机会完全相同的条件下,大蚊笼受精雌蚊吸血率为59.88%,未受精雌蚊的吸血率为35.38%;小蚊笼受精雌蚊的吸血率为74.13%,未受精雌蚊吸血率仅为43.56%。正常交配雌蚊的吸血率为49.71%,未进行交配的处女雌蚊吸血率为28.42%。同为正常交配蚊群,喂血组雌蚊受精率55.85%,不喂血组的受精率为44.51%。初步认为大劣按蚊的吸血活动与交配受精有一定的关系。     

大劣按蚊在实验条件下交配习性的观察

我们在实验室建立了大劣按蚊自然交配种群之后,对其交配习性进行了观察。饲养初期,养蚊笼大小对其交配有一定的影响,在大蚊笼饲养交配受精率高,反之则低,饲养23代以后,两者已无明显差异。在同笼内,雌雄蚊的比例,以1:1.5者交配受精率高;1:1者低;1:2者则处于不稳定状态。大劣按蚊羽化至少在48小时后才能进行交配,随着蚊龄增长,交配受精率逐步增加,初步认为21天的蚊龄仍有交配行为存在。     

大劣按蚊雄蚊的交配能力和日龄及交配次数对其生殖系统形态学影响的观察

本文在实验室条件下,观察大劣按蚊(Anopheles dirus)雄蚊交配能力和日龄、交配及交配后间歇期对其生殖系统形态学的影响。羽化后1小时可见丝状精子,22小时尾器全部旋转180°。3—12日龄雄蚊交配能力最强。随着日龄增加,精囊数逐渐减少,睾丸内成熟精子占据整个睾丸的比例逐渐增加,附腺透明区宽度变窄直至消失。多次交配比一次交配后,其睾丸内精子量减少、透明区宽度增加明显;交配后经过一定间歇期后,生殖系统能重新恢复活力,但多次交配后其恢复程度和速度远比交配一次者为慢。大劣按蚊雄蚊生殖系统的变化可初步判断其日龄和交配史。     

大劣按蚊雄蚊的交配能力和日龄及交配次数对其生殖系统形态学影响的观察

本文在实验室条件下,观察大劣按蚊(Anopheles dirus)雄蚊交配能力和日龄、交配及交配后间歇期对其生殖系统形态学的影响.羽化后1小时可见丝状精子,22小时尾器全部旋转180°.3—12日龄雄蚊交配能力最强.随着日龄增加,精囊数逐渐减少,睾丸内成熟精子占据整个睾丸的比例逐渐增加,附腺透明区宽度变窄直至消失.多次交配比一次交配后,其睾丸内精子量减少、透明区宽度增加明显;交配后经过一定间歇期后,生殖系统能重新恢复活力,但多次交配后其恢复程度和速度远比交配一次者为慢.大劣按蚊雄蚊生殖系统的变化可初步判断其日龄和交配史.     

食蟹猴疟原虫B株子孢子感染后供蚊血餐感染时间的初步观察

食蟹猴疟原虫Ｂ株子孢子感染后供蚊血餐感染时间的初步观察宋宗臣第三军区大学寄生虫学教研室重庆６３００３８食蟹猴疟原虫Ｂ株－按蚊－恒河猴系统是疟疾根治药物研究较理想的模型。在使用此模型时,获得好的感染蚊批是重要环节。１９８４年我国引进此株疟原虫后,对子孢...     

Selection of Anopheles dirus for refractoriness and susceptibility to Plasmodium yoelii nigeriensis

Two lines of the Oriental malaria vector mosquito Anopheles dirus species A (Diptera: Culicidae), one fully refractory and one fully susceptible to Plasmodium yoelii nigeriensis (an African rodent malaria parasite), were established after 17 generations of mass selection, followed by single female selection for one or two generations. Prior to selection, the stock colony of An. dirus was 17% refractory. Both lines of An. dirus produced abundant ookinetes that started to invade the midgut within 24h post-infection, as seen in histological sections. In most of the refractory mosquitoes, oocysts stopped development <12 h post-invasion, indicating a rapid defence mechanism. Dead P. y. nigeriensis parasites were apparently localized as small melanized spots (2-5 microm) seen in wet preparations of mosquito midguts dissected 5-7 days post infective bloodmeal. In some refractory An. dirus females, apart from the spots, a small number of totally encapsulated oocysts (c. 10 microm) were also present. These larger melanized parasites predominated in a few females: they appeared 2-3 days post-infection as a secondary delayed defence mechanism. The progeny of reciprocal matings between susceptible and refractory lines had approximately 50% susceptibility. Backcrosses of F1 hybrids with susceptible or refractory lines increased or decreased the susceptibility of backcross progeny accordingly. Overall, these results suggest polygenic control of susceptibility to P. y. nigeriensis infection. The refractory line of An. dirus showed normal susceptibility to natural infections of the human malarias P. falciparum and P. vivax from local patients.     

Nucleoside permeation in mouse erythrocytes infected with Plasmodium yoelii

In normal mouse erythrocytes, nucleoside permeation was almost completely blocked in the presence of binding site-saturating concentrations of nitrobenzylthioinosine, whereas permeation in erythrocytes infected with the malarial parasite, Plasmodium yoelii, was substantial under these conditions, suggesting the presence of a permeation mechanism of low sensitivity to nitrobenzylthioinosine in the infected cells. Binding sites for nitrobenzylthioinosine were more numerous on infected erythrocytes than on uninfected cells. When mice infected with P. yoelii were treated with combinations of tubercidin and nitrobenzylthioinosine 5'-monophosphate, progression of parasitemia was delayed and survival times were increased.     

Plasmodium yoelii: contribution of oocysts melanization to natural refractoriness in Anopheles dirus

It is well known that Anopheles dirus is naturally refractory to rodent malaria parasite, Plasmodium yoelii, but the mechanism is still largely unknown. Here, we found that some P. yoelii taken into An. dirus could develop into oocysts, but oocysts were partially melanized at 7 days and completely melanized at 15 days post-infectious blood meal. Transmission electronic microscopy could find the melanized P. yoelii oocysts in An. dirus as early as 5 days post-infection, with a few haemocytes attaching to the melanized oocysts, indicating a typical humoral melanization reaction. Although the change of protein pattern at 24h post-infection suggested that other unknown mechanisms and/or factors might be involved in killing ookinetes, our data implied that oocysts melanization was one of the mechanisms of An. dirus to block P. yoelii development. In addition, activity of phenoloxidase, such as monophenol oxidase and o-diphenoloxidase, in haemolymph of An. dirus fed on infectious blood meal was much higher than that of mosquitoes fed on 5% glucose or normal mouse blood (p<0.05), implying the possible role of PO in oocysts melanization by An. dirus.     

Parasite-induced processes for adenosine permeation in mouse erythrocytes infected with the malarial parasite Plasmodium yoelii.

In fura-2-loaded A10 vascular smooth-muscle cells, 1 nM-vasopressin and 200 nM-endothelin evoked a rapid transient rise in intracellular free Ca2+ concentration [( Ca2+]i), which was then followed by a maintained elevation of [Ca2+]i. The maintained elevation of [Ca2+]i was only partially inhibited by 5 microM-nifedipine, but completely abolished in the presence of 1 mM-EGTA. When extracellular Ca2+ was replaced with 1 mM-Mn2+ (Mn2+ quenches fura-2 fluorescence), both endothelin and vasopressin evoked an Mn2+ quench of the fluorescence from the intracellularly trapped fura-2, even in the presence of 5 microM-nifedipine. These data suggest that both vasopressin and endothelin promote a bivalent-cation influx and provide further evidence for receptor-mediated Ca2+ entry in vascular smooth muscle.     

Igh-C allotype-linked control of anti-DNA production and clonotype expression in mice infected with Plasmodium yoelii

The infection of nonlethal strain of Plasmodium yoelii induces the formation of IgG anti-DNA antibodies as a result of polyclonal B cell activation. By using various nonautoimmune strains of mice including H-2 or Igh congenic or recombinant mice, the levels and clonotypes of anti-DNA antibodies elicited by the malaria infection were analyzed in relation to the expression of the MHC or Igh gene. Our results showed there were little, if any, differences in serum anti-DNA levels and their clonotypes among B10 and B6 H-2 congenic mice. In contrast, malaria-induced IgG anti-DNA responses markedly differed quantitatively and clonotypically between murine strains bearing the Ighb allotype and those bearing the Igha, Ighj, Ighd, or Ighn allotype. The latter group of mice produced approximately 5 to 10 times more IgG anti-DNA antibodies than the former group of mice. Clonotypically, mice bearing the Ighb allotype developed high alkaline anti-DNA antibodies of pH 8.0 to 8.5, whereas non-Ighb mice failed to express such alkaline anti-DNA spectrotypes, and exhibited more neutral spectrotypes (pH 7.0 to 8.0). Studies on the Igh recombinant mice indicated that the observed quantitative and clonotypical differences in IgG anti-DNA production was not associated with the variable region, but with the constant region of the Igh gene complex. Our results have suggested that IgG anti-DNA responses occurring as a result of polyclonal B cell activation during the course of malaria infection markedly differs quantitatively and clonotypically among murine strains and appear to be controlled at least in part by the Igh-C gene or gene(s) closely linked to it.     

Plasmodium yoelii: blood oxygen and brain function in the infected mouse

The carriage of oxygen by the blood and the in vivo response of the brain were investigated in mice infected with a lethal strain of Plasmodium yoelii. All mice with parasitaemia exceeding 70% were severely anaemic (Hb 3.5 +/- 1.8 g/dl; mean +/- 1 SD), acidotic (blood pH 7.04 +/- 0.06) and hypoglycaemic (blood glucose 0.6 +/- 0.76 mumol/ml). The oxyhaemoglobin dissociation curve (ODC) of blood from heavily infected mice was shifted right as compared to controls, but the increase in p50 was less than expected from the accompanying acidosis. The reduced shift right was due to a decrease in the 2,3-DPG/Hb ratio in infected animals (0.72 +/- 0.12, n = 17 vs 1.10 +/- 0.09, n = 12 in controls). Despite the severity of terminal infection, the cerebral pH and the relative steady-state concentrations of PCr, ATP and Pi measured in vivo by nuclear magnetic resonance (31P NMR) were normal. Alterations in brain energy status and pH cannot account for cerebral signs or death in this proposed mouse model of cerebral malaria.     

Antibacterial activity of silkworm hemolymph after hemopoietic organ being injured with radiosurgery

Abstract:  To study the effect of hemopoietic organs damage on hemocyte function and antibacterial activity of hemolymph, silkworm ( Bombyx mori ) larvae were locally irradiated with carbon ion beams (¹²C⁵⁺, 100 Gy), live and death ratio of hemocytes and antibacterial activity of hemolymph were investigated. For unirradiated controls, the ratio of died hemocytes hardly changed at the fifth instar, but for locally irradiated silkworms, with growth died hemocytes and low-functional hemocytes increased clearly, and reached an extremely significant level at the later stage of the fifth instar. For irradiated individuals, the phenolxidase activities and sterilization effect of hemolymph were clearly lower than those of controls. So it is considered that after irradiating hemopoietic organs with heavy ion beams, not only the number of hemocytes decreased but the function of hemocytes also dropped, and they at last lead to a decline in immunity.     

Oral delivery of curcumin bound to chitosan nanoparticles cured Plasmodium yoelii infected mice

Curcumin has been shown to have anti malarial activity, but poor bioavailability and chemical instability has hindered its development as a drug. We have bound curcumin to chitosan nanoparticles to improve its bioavailability and chemical stability. We found that curcumin bound to chitosan nanoparticles did not degrade that rapidly in comparison to free curcumin when such particles were incubated in mouse plasma in vitro at room temperature. The uptake of bound curcumin from chitosan nanoparticles by mouse RBC was much better than from free curcumin. Oral delivery of curcumin bound chitosan nanoparticles to normal mice showed that they can cross the mucosal barrier intact and confocal microscopy detected the nanoparticles in the blood. Curcumin loaded chitosan nanoparticles when delivered orally improved the bioavailability of curcumin in the plasma and RBC. While mice infected with a lethal strain of Plasmodium yoelii (N-67) died between 8 and 9 days post infection, feeding of chitosan nanoparticles alone made them to survive for five more days. Feeding 1mg of native curcumin to infected mice per day for seven days resulted in survival of one third of mice but under the same condition when 1mg of curcumin bound to chitosan nanoparticles was fed all the mice survived. Like chloroquine, curcumin inhibited parasite lysate induced heme polymerization in vitro in a dose dependent manner and curcumin had a lower IC(50) value than chloroquine. We believe that binding of curcumin to chitosan nanoparticles increases its chemical stability and enhances its bioavailability when fed to mice. In vitro data suggest that it can inhibit hemozoin synthesis which is lethal for the parasite.     

Comparative histopathology of mice infected with the 17XL and 17XNL strains of Plasmodium yoelii

Plasmodium yoelii 17XL was used to investigate the mechanism of Plasmodium falciparum-caused cerebral malaria, although its histological effect on other mouse organs is still unclear. Here, histological examination was performed on mice infected with P. yoelii 17XL; the effect of P. yoelii 17XL infection on anemia and body weight loss, as well as its lesions in the brain, liver, kidney, lung, and spleen, also was investigated. Plasmodium yoelii 17XL-infected red blood cells were sequestered in the microcirculation of the brain and in the kidney. Compared with the nonlethal P. yoelii 17XNL strain, infection by P. yoelii 17XL caused substantial pulmonary edema, severe anemia, and significant body weight loss. Although P. yoelii 17XNL and 17XL produced a similar focal necrosis in the mouse liver, infection of P. yoelii 17XL induced coalescing of red and white pulp. Mortality caused by P. yoelii 17XL may be due to cerebral malaria, as well as respiratory distress syndrome and severe anemia. Plasmodium yoelii 17XL-infected rodent malaria seems to be a useful model for investigating severe malaria caused by P. falciparum.