Interactions between the gut micro-community and transcriptome of Culex pipiens pallens under low-temperature stress.

BACKGROUND: Culex pipiens pallens (Diptera: Culicidae) can survive at low temperature for long periods. Understanding the effects of low-temperature stress on the gut microflora and gene expression levels in Cx. pipiens pallens, as well as their correlation, will contribute to the study of the overwintering mechanism of Cx. pipiens pallens. METHODS: The gut bacteria were removed by antibiotic treatment, and the survival of Cx. pipiens pallens under low-temperature stress was observed and compared with the control group. Then, full-length 16S rRNA sequencing and the Illumina HiSeq X Ten sequencing platform were used to evaluate the gut microflora and gene expression levels in Cx. pipiens pallens under low-temperature stress. RESULTS: Under the low-temperature stress of 7 °C, the median survival time of Cx. pipiens pallens in the antibiotic treatment group was significantly shortened by approximately 70% compared to that in the control group. The species diversity index (Shannon, Simpson, Ace, Chao1) of Cx. pipiens pallens decreased under low-temperature stress (7 °C). Non-metric multidimensional scaling (NMDS) analysis divided all the gut samples into two groups: control group and treatment group. Pseudomonas was the dominant taxon identified in the control group, followed by Elizabethkingia and Dyadobacter; in the treatment group, Pseudomonas was the dominant taxon, followed by Aeromonas and Comamonas. Of the 2417 differentially expressed genes (DEGs), 1316 were upregulated, and 1101 were downregulated. Functional GO terms were enriched in 23 biological processes, 20 cellular components and 21 molecular functions. KEGG annotation results showed that most of these genes were related to energy metabolism-related pathways. The results of Pearson's correlation analysis showed a significant correlation between the gut microcommunity at the genus level and several DEGs. CONCLUSIONS: These results suggest that the mechanism of adaptation of Cx. pipiens pallens to low-temperature stress may be the result of interactions between the gut bacterial community and transcriptome.

Epidemiological analysis of 133 malaria cases in Shanxian county, Shandong Province, China.

OBJECTIVE: To conduct an analysis of the epidemiological changes in malaria that have occurred in Shanxian county from 2002 to 2016. METHODS: A retrospective study was conducted and data were collected from web-based reporting system to explore the epidemiological characteristics in Shanxian county from 2002 to 2016. All individual case information was obtained from village malaria servicers organized by the local Shandong Institute of Parasitic Diseases. RESULTS: A total of 133 cases were identified as malaria in Shanxian county during this period, including 124 indigenous cases (93.2%) and 9 imported cases (6.8%). The 124 indigenous malaria cases were infected with Plasmodium vivax (P. vivax), whereas 7 of the 9 confirmed imported cases were infected with Plasmodium falciparum (P. falciparum), 1 was infected with Plasmodium ovale (P. ovale) and 1 patient was infected with P. falciparum mixed with P. vivax. The total number of malaria cases included 86 males (64.7%) and 47 females (35.3%). Age of the patients ranged from 1 to 83 years, although most (64.7%) infections occurred in the 21-to 60-year-old age group. Remarkably, 117 of the total malaria cases (98.0%) were reported from 2006 to 2011. The epidemic season was from June to October, with the peak occurring yearly from July to September. The most common occupation of the infected patients was farmer. In total, 58.1% of the cases occurred in 3 townships, namely, Fugang, Huanggang and Caozhuang. CONCLUSIONS: In Shanxian county, the local malaria incidence experienced an emerge-peak-control-eliminate status. However, due to the numbers of migrant labourers returning from Africa, imported cases were continuous and presented an increasing annual trend, which became a non-negligible and a significant impediment for malaria elimination. Therefore, the need to eliminate instances of malaria reintroduction to receptive malaria-free areas should drive strategies to align with the epidemiological changes.

[Research Progress on the Molecular Mechanisms of Mosquito Innate Immunity].

As the important vector of the mosquito-borne diseases, mosquitos rely on their innate immune system against pathogens infection, which includes cellular immunity and humoral immunity. Both of them are interacted and coordinated, via the pattern recognition receptors, immune signaling, antimicrobial peptides, phenoloxidase-based melanization, phagocytosis, and so on. This paper reviews the research progress on the molecular mechanisms of mosquito innate immunity.

[Sequence analysis of ribosomal DNA internal transcribed spacer 2 of sympatric populations of Anopheles sinensis of different feeding preferences].

OBJECTIVE: To investigate the existence of genetic divergence of sympatric populations of Anopheles sinensis of different feeding preferences based on the rDNA-ITS2 sequence differences. METHODS: A large number of wild anopheles populations were trapped all night by man-baited net and calf-baited net that had been set up between high-density natural villages of An. sinensis populations and vector-breeding sites, from which two groups of An. sinensis were separated by morphological identification and brought back to the lab for conventional breeding. A large closed greenhouse which temperature and humidity was appropriate was selected as research settings of mark-release-recapture methods by female mosquitoes, in the center of which above An. sinensis populations baited by man and calf and respectively correspondingly marked by red and yellow phosphors were released in together, in each side of which An. sinensis were recaptured simultaneously by man-baited net and calf-baited net. An. sinensis populations trapped by man twice were brought back to the lab and bred with man-blood, correspondingly ones trapped by calf with calf-blood. Man-preferring and calf-preferring strains were screened respectively from An. sinensis which had been baited by man and calf by the mark-release-recapture methods after parent and F1 mosquitoes, and sequencing and aligning of both rDNA-ITS2 were conducted via PCR amplification. RESULTS: The recapture ratios of wild parental mosquitoes An. sinensis of man-preferring group by man-baited net and calf-baited net were 54.07% (339/627) and 45.93% (288/627) respectively, and ones of calf-preferring group by man-baited net and calf-baited net were 58.01% (409/705) and 41.99% (296/ 705) respectively. Two groups of parental mosquitoes trended towards selecting the original blood hosts in host-seeking preference (Χ2 = 19.42, P < 0.01). The recapture ratios of F1 mosquitoes An. sinensis of man-preferring group by man-baited net and calf-baited net were 63.43% (765/1 206) and 36.57% (441/1 206), and ones of calf-preferring group by man-baited net and calf-baited net were 68.22% (1 039/1 523) and 31.78% (484/1 523). Two groups of F1 mosquitoes had more significant characteristics of selecting the original blood hosts in host-seeking preference (Χ2 = 271.69, P < 0.01) and showed the genetic differentiation phenomenon, but the results of sequencing and aligning of the rDNA-ITS2 via PCR amplification showed no difference in base sequence between the two strains and both were 469 bp. CONCLUSIONS: The genetic divergence based on the rDNA-ITS2 sequence does not happen in An. sinensis sympatric populations of different feeding preferences.

[Experimental observation on host preference of Anopheles sinensis].

OBJECTIVE: To observe the host preference of Anopheles sinensis captured by outdoor human or cattle baits. METHODS: A large number of non-blood-fed An. sinensis females were collected by overnight trapping outdoor with human and cattle in the rice paddy field in Shan County of Shandong Province, and took back to the lab, and individually labeled as human baits group and cattle baits group, fed with mouse blood. The host preference of parent, F1 and F25 generations of the two groups were observed by mark-release-recapture methods in a large greenhouse. RESULTS: The recapture rates of parent, F1 and F25 generations were 39.02% (1332/3414), 37.97% (2583/6803), and 30.55% (1523/4986), respectively. In parent generation, the proportion of mosquitoes from human baits group and cattle baits group collected by human-bait and cattle-bait was 54.07% (339/627) and 58.01% (409/705), respectively (χ2=19.42, P<0.01); in F1 generation, that of the two groups was 51.03% (669/1311) and 55.11% (701/1272), respectively (χ2= 9.75, P<0.01); in F25 generation, that of the two groups was 51.98% (342/658) and 52.37 (453/865), respectively (χ2=2.82, P>0.05). CONCLUSION: After culture for 25 generations in an experimental condition, the host preference for human or cattle of An. sinensis maybe change.

The dynamic changes of plasma neuropeptide y and neurotensin and their role in regulating cerebral hemodynamics in neonatal hypoxic-ischemic encephalopathy.

Hypoxic-ischemic encephalopathy (HIE) is a common cause of neonatal encephalopathy and is one of the most important causes of neonatal death and disabilities, especially those infants with moderate to severe encephalopathy. However, the pathogenesis of HIE still remains unclear. The purpose of this study was to explore the dynamic changes in plasma neuropeptide Y (NPY) and neurotensin (NT) as well as their role in regulating cerebral hemodynamics in HIE patients. The plasma levels of NPY and NT in the umbilical artery and peripheral blood on the first, third, and seventh days after birth in 40 term infants with HIE and 40 healthy controls were measured using radioimmunoassay. On the first day of life, the blood samples were collected immediately when ultrasound examinations were finished. The ultrasound transducer was placed on the temporal fontanelle to detect the hemodynamic parameters of the middle cerebral artery, including peak systolic flow velocity, end-diastolic flow velocity, time-average mean velocity, pulsatility index, and resistance index (RI) in both groups were measured by pulse Doppler ultrasound in the first day after birth. The relationship between RI and NPY or NT was analyzed by linear regression analysis. NPY levels in umbilical blood ([mean +/- standard deviation] 615.5 +/- 130.7 ng/L) and first-day peripheral blood (355.9 +/- 57.4 ng/L) in neonates with HIE were significantly higher than those in normal newborns' blood (199.1 +/- 63.2 and 214.4 +/- 58.0 ng/L, respectively; P < 0.01). NPY levels in HIE neonates then declined to control levels on the third day after birth ( P > 0.05). However, the levels of plasma NT in umbilical blood and peripheral blood were much higher in the HIE group than those in normal newborns during the first week ( P < 0.01). The results of Doppler ultrasound examinations showed that cerebral blood flow velocity significantly decreased, whereas RI increased markedly in HIE patients compared with healthy controls ( P < 0.01). Linear regression analysis revealed that the RI was positively correlated with NPY levels ( R = 0.614; P < 0.01) and negatively correlated with NT levels ( R = -0.579; P < 0.01). The results of this study showed that there was a significant increase in plasma NPY and NT levels in HIE patients and this was strongly related to the severity of HIE, and the hemodynamic parameter RI was significantly correlated with NPY and NT. Therefore, we believe that the dynamic changes in plasma NPY or NT levels participate in the mechanisms of HIE by regulating cerebral hemodynamic changes after neonatal asphyxia occurs.