Jingze Liu

Abundance and seasonal activity of Haemaphysalis concinna (Acari: Ixodidae) at the border between China and Russia in Northern Inner Mongolia, China

BackgroundHaemaphysalis concinna, a three-host tick vector of several pathogens, poses a high risk to the health of humans and livestock. However, knowledge of the seasonal activities, relative density and other ecological characteristics of this tick is quite limited and fragmentary. This knowledge gap represents a bottleneck in our understanding of the health risks associated with tick-borne pathogens.MethodsWe conducted a two-year study from April 2012 to March 2014 in Northern Inner Mongolia situated on the China-Russia border, China, to investigate the seasonal activities and relative density of the three developmental stages of H. concinna. During the study period, feeding ticks were removed weekly from domestic sheep and their attachment sites were recorded. Questing ticks were collected weekly from five habitats (broadleaf forest, coniferous forest, shrubs, grassland and mixed coniferous forest) using the flagging-dragging method of capture. Rodents were captured and examined on two consecutive nights each week from June to September in 2012.ResultsH. concinna ticks were found mainly in shrubs and grasslands habitats. Adults were encountered from February to October with the major peak occurring in June. Larvae, which were observed mainly from late April to late September, reached peak numbers in late July. Nymphs were observed mainly from March to October, and their numbers peaked in early July. H. concinna adults and nymphs were found attached to sheep and their most favored sites of attachment were the face and ears. H. concinna larvae were found on two rodent species, Apodemus peninsulae and Eutamias sibiricus.ConclusionThe relative density and seasonal activities of H. concinna have been systematically reported for Northern Inner Mongolia, China. The information about the hosts infested by H. concinna and its preferred attachment sites on sheep will help efforts to control this tick and the tick-borne diseases carried by it.

Ticks (Acari: Ixodoidea: Argasidae, Ixodidae) of China

This paper presents results of an investigation and listing of tick species found in China during a survey in all 28 provinces. This will be a step towards a definitive list of tick species and their distribution. To date, the tick fauna of this area consists of 117 species in the following families: Argasidae-Argas (7 species), Carios (4 species) and Ornithodoros (2 species); Ixodidae-Amblyomma (8 species), Anomalohimalaya (2 species), Dermacentor (12 species), Haemaphysalis (44 species), Hyalomma (6 species), Ixodes (24 species) and Rhipicephalus (8 species). Some well known ticks carrying and transmitting many infectious agents to man and domestic animals are also found in China. These include Ixodespersulcatus, Haemaphysalislongicornis, Rhipicephalussanguineus, R. (Boophilus) microplus and Hyalommaasiaticum. It is worth mentioning that Ixodes rangtangensis Teng and Haemaphysalis xinjiangensis Teng should be relegated to a synonym of I. moschiferi and Hae. danieli, respectively. The distribution of ticks over the provinces of China is also discussed. The information on ticks in some areas such as Henan is not exhaustive.

Curcumin Inhibits Proliferation and Induces Apoptosis of Human Colorectal Cancer Cells by Activating the Mitochondria Apoptotic Pathway

Curcumin, a natural plant extract from Curcuma longa, is known for its anti‐carcinogenic and chemopreventive effects on a variety of experimental cancer models. In this study, we evaluated the effects of curcumin and elucidated its mechanism in human colorectal carcinoma cells. Cell viability assay showed that curcumin significantly inhibited the growth of LoVo cells. Curcumin treatment induced the apoptosis accompanied by ultra‐structural changes and release of lactate dehydrogenase in a dose‐dependent manner. Moreover, treatment with 0–30 µg/mL curcumin decreased the mitochondrial membrane potential and activated the caspase‐3 and caspase‐9 in a dose‐ and time‐dependent manner. Nuclear and annexin V/PI staining showed that curcumin induced the apoptosis of LoVo cells. FACS analysis revealed that curcumin could induce the cell cycle arrest of LoVo cells at the S phase. Furthermore, western blotting analysis indicated that curcumin induced the release of cytochrome c, a significant increase of Bax and p53 and a marked reduction of Bcl‐2 and survivin in LoVo cells. Taken together, our results suggested that curcumin inhibited the growth of LoVo cells by inducing apoptosis through a mitochondria‐mediated pathway. Copyright

Two novel antimicrobial peptides from centipede venoms

Centipede venoms are complex mixtures of biochemically and pharmacologically active components such as peptides and proteins. Very few are known about their pharmacological actions. The present work reports the structural and functional characterization of two antimicrobial peptides (scolopin 1 and -2) identified from centipede venoms of Scolopendra subspinipes mutilans by Sephadex gel filtration and reverse-phase high-performance liquid chromatography (RP-HPLC). The amino acid sequences of scolopin 1 and -2 were FLPKMSTKLRVPYRRGTKDYH and GILKKFMLHRGTKVYKMRTLSKRSH determined by Edman degradation and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). Both scolopin 1 and -2 showed strong antimicrobial activities against tested microorganisms including Gram-positive/negative bacteria and fungi. They also showed moderate hemolytic activity against both human and rabbit red cells. This is the first report of antimicrobial peptides from centipedes.

A novel serine protease inhibitor from Bungarus fasciatus venom.

By Sephadex G-50 gel filtration, cation-exchange CM-Sephadex C-25 chromatography and reversed phase high-performance liquid chromatography (HPLC), a novel serine protease inhibitor named bungaruskunin was purified and characterized from venom of Bungarus fasciatus. Its cDNA was also cloned from the cDNA library of B. fasciatus venomous glands. The predicted precursor is composed of 83 amino acid (aa) residues including a 24-aa signal peptide and a 59-aa mature bungaruskunin. Bungaruskunin showed maximal similarity (64%) with the predicted serine protease inhibitor blackelin deduced from the cDNA sequence of the red-bellied black snake Pseudechis porphyriacus. Bungaruskunin is a Kunitz protease inhibitor with a conserved Kunitz domain and could exert inhibitory activity against trypsin, chymotrypsin, and elastase. By screening the cDNA library, two new B chains of beta-bungarotoxin are also identified. The overall structures of bungaruskunin and beta-bungarotoxin B chains are similar; especially they have highly conserved signal peptide sequences. These findings strongly suggest that snake Kunitz/BPTI protease inhibitors and neurotoxic homologs may have originated from a common ancestor.

Molecular cloning and characterization of novel cathelicidin-derived myeloid antimicrobial peptide from Phasianus colchicus.

Cathelicidins were initially characterized as a family of antimicrobial peptides. Now it is clear that they fulfill several immune functions in addition to their antimicrobial activity. In the current work, three cDNA sequences encoding pheasant cathelicidins were cloned from a constructed bone marrow cDNA library of Phasianus colchicus, using a nested-PCR-based cloning strategy. The three deduced mature antimicrobial peptides, Pc-CATH1, 2 and 3 are composed of 26, 32, and 29 amino acid residues, respectively. Unlike the mammalian cathelicidins that are highly divergent even within the same genus, Pc-CATHs are remarkably conserved with chicken fowlicidins with only a few of residues mutated according to the phylogenetic analysis result. Synthetic Pc-CATH1 exerted strong antimicrobial activity against most of bacteria and fungi tested, including the clinically isolated (IS) drug-resistant strains. Most MIC values against Gram-positive bacteria were in the range of 0.09-2.95 μM in the presence of 100mM NaCl. Pc-CATH1 displayed a negligible hemolytic activity against human erythrocytes, lysing 3.6% of erythrocytes at 3.15 μM (10 μg/ml), significantly higher than the corresponding MIC. Pc-CATH1 was stable in the human serum for up to 72 h, revealing its extraordinary serum stability. These specific features of Pc-CATH1 may make its applications much wider given the potency and breadth of the peptides bacteriocidal capacity and its resistance towards serum and high-salt environments.

Antimicrobial peptides from the venoms of Vespa bicolor Fabricius.

Hornets possess highly toxic venoms, which are rich in toxins, enzymes and biologically active peptides. Many bioactive substances have been identified from wasp venoms. Vespa mastoparan (MP-VBs) and Vespa chemotatic peptide presenting antimicrobial action (VESP-VBs) were purified and characterized from the venom of the wasp, Vespa bicolor Fabricius. The precursors encoding VESP-VBs and MP-VBs were cloned from the cDNA library of the venomous glands. Analyzed by FAB-MS, the amino acid sequence and molecular mass for VESP-VB1 were FMPIIGRLMSGSL and 1420.6, for MP-VB1 were INMKASAAVAKKLL and 1456.5, respectively. The primary structures of these peptides are homologous to those of chemotactic peptides and mastoparans isolated from other vespid venoms. These peptides showed strong antimicrobial activities against bacteria and fungi and induced mast cell degranulation, but displayed almost no hemolytic activity towards human blood red cells.

Tick-borne pathogens and the vector potential of ticks in China

Ticks, as obligate blood-sucking ectoparasites, attack a broad range of vertebrates and transmit a great diversity of pathogenic microorganisms. They are considered second only to mosquitoes as vectors of human disease, and the most important vector of pathogens of domestic and wild animals. Of the 117 described species in the Chinese tick fauna, 60 are known to transmit one or more diseases: 36 species isolated within China and 24 species isolated outside China. Moreover, 38 of these species carry multiple pathogens, indicating the potentially vast role of these vectors in transmitting pathogens. Spotted fever is the most common tick-borne disease, and is carried by at least 27 tick species, with Lyme disease and human granulocytic anaplasmosis ranked as the second and third most widespread tick-borne diseases, carried by 13 and 10 species, respectively. Such knowledge provides us with clues for the identification of tick-associated pathogens and suggests ideas for the control of tick-borne diseases in China. However, the numbers of tick-associated pathogens and tick-borne diseases in China are probably underestimated because of the complex distribution and great diversity of tick species in this country.

The novel antimicrobial peptides from skin of Chinese broad-folded frog, Hylarana latouchii (Anura:Ranidae).

Broad-folded frogs (Hylarana latouchii), one member of 12 species of the genus Hylarana in the Chinese frog fauna, are widely distributed in the South of China. In this study, we purified and characterized three antimicrobial peptides from the skin secretion of H. latouchii. Five different cDNA fragments encoding the precursors of these antimicrobial peptides were cloned, and five mature antimicrobial peptides belonging to two different families were deduced from the five cDNAs. Structural characterization of the mature peptides had identified them as members of the brevinin-1 and temporin families. They were named brevinin-1LTa (FFGTALKIAANVLPTAICKILKKC), brevinin-1LTb (FFGTALKIAANILPTAICKILKKC), temporin-LTa (FFPLVLGALGSILPKIF-NH(2)), temporin-LTb (FIITGLVRGLTKLF-NH(2)) and temorin-LTc (SLSRFLSFLKIVYPPAF-NH(2)). Brevinin-1LTa, temporin-LTa, temporin-LTb and temporin-LTc with different antimicrobial activities induced significant morphological alterations of the tested microbial surfaces as shown by scanning electron microscopy, which indicated strong membrane disruption.

The life cycle of Hyalomma asiaticum kozlovi Olenev, 1931 (Acari: Ixodidae) under laboratory conditions

The developmental stages in the life cycle of Hyalomma asiaticum kozlovi were investigated under laboratory conditions. The larval, nymphal and adult ticks were all fed on rabbits at 25-27 degrees C, 50% relative humidity (RH) and exposed to daylight. All free-living stages were maintained in an incubator at 26+/-1 degrees C, 70% RH and daylight conditions. The life cycle of H. asiaticum kozlovi was completed in an average period of 151.6 days (range 104-190). The average developmental periods were 38.8 days for egg incubation, 2.1, 5.8 and 10.7 days for larval prefeeding, feeding and premoulting, and 3.3, 6.0 and 26.0 days for the same stages of nymphs, respectively. The average times for prefeeding, feeding, preoviposition and oviposition of female adult ticks were 1.4, 10.1, 20.9, and 26.5 days, respectively. The results confirmed the significant correlation between the weight of the engorged female and the amount of the egg mass laid (r=0.9641, p<0.05). The reproductive efficiency index (REI) and reproductive fitness index (RFI) in females were 8.82 and 7.56, respectively. Engorged nymphs moulting to females were significantly heavier (33.3+/-0.65 mg) than those moulting to males (27.1+/-0.79 mg). The overall sex ratio of the adult ticks was 1:1.07 (M:F).