Exploring a Hirudin variant from nonhematophagous leeches: Unraveling full-length sequence, alternative splicing, function, and potential as a novel anticoagulant polypeptide

ETHNOPHARMACOLOGICAL RELEVANCE

Leeches exhibit robust anticoagulant activity, making them useful for treating cardiovascular diseases in traditional Chinese medicine. Whitmania pigra, the primary source species of leech-derived medicinal compounds in China, has been demonstrated to possess formidable anticoagulant properties. Hirudin-like peptides, recognized as potent thrombin inhibitors, are prevalent in hematophagous leeches. Considering that W. pigra is a nonhematophagic leech, the following question arises: does a hirudin variant exist in this species?

AIM OF THE STUDY

In this study we identified the hirudin-encoding gene (WP_HV1) in the W. pigra genome. The goal of this study was to assess its anticoagulant activity and analyze the related mechanisms.

MATERIALS AND METHODS

In this study, a hirudin-encoding gene, WP_HV1, was identified from the W. pigra genome, and its accurate coding sequence (CDS) was validated through cloning from cDNA extracted from fresh W. pigra specimens. The structure of WP_HV1 and the amino acids associated with its anticoagulant activity were determined by sequence and structural analysis and prediction of its binding energy to thrombin. E. coli was used for the expression of WP_HV1 and recombinant proteins with various structures and mutants. The anticoagulant activity of the synthesized recombinant proteins was then confirmed using thrombin time (TT).

RESULTS

Validation of the WP_HV1 gene was accomplished, and three alternative splices were discovered. The TT of the blank sample exceeded that of the recombinant WP_HV1 sample by 1.74 times (0.05 mg/ml), indicating positive anticoagulant activity. The anticoagulant activity of WP_HV1 was found to be associated with its C-terminal tyrosine, along with the presence of 9 acidic amino acids on both the left and right sides. A significant reduction in the corresponding TT was observed for the mutated amino acids compared to those of the wild type, with decreases of 4.8, 6.6, and 3.9 s, respectively. In addition, the anticoagulant activity of WP_HV1 was enhanced and prolonged for 2.7 s when the lysine-67 residue was mutated to tryptophan.

CONCLUSION

Only one hirudin-encoding variant was identified in W. pigra. The active amino acids associated with anticoagulation in WP_HV1 were resolved and validated, revealing a novel source for screening and developing new anticoagulant drugs.

Quantitative proteomics based bioactive proteins discovery and quality control of medicinal leeches

ETHNOPHARMACOLOGICAL RELEVANCE

Leech, a classical traditional Chinese medicine for promoting blood circulation and removing blood stasis, is mainly used in the clinical treatment of cardiovascular and cerebrovascular diseases. The discovery of activity proteins or peptides in the dead and dried medicinal leech is an important task with great challenges.

AIM OF THE STUDY

The aim of this study was to provide a basic proteome profile and help further discover active proteins and quality control for medicinal leeches, which would also provide insight into the research of animal medicines.

MATERIALS AND METHODS

Seventeen batches of dried medicinal leeches covering three species were collected from medicinal markets, which were authenticated by DNA barcoding. Then the proteome of different species leeches was profiled to reveal the significantly different proteins using label-free proteomics. The characteristic peptides were screened out based on biological pathways analysis, which were further absolutely quantified using the developed stable isotope-labeled based parallel reaction monitoring method.

RESULTS

Seventeen batches of leech materials were Whitmania pigra Whitman (WP), Whitmania laevis Whitman (WL) and Poecilobdella manillensis Lesson (PM), respectively. A total of 1,035 proteins (452 in WP, 425 in WL and 158 in PM) were identified. Among them, 90 overlapping proteins were mainly concentrated in diverse metabolic pathways and primarily localized in the cytoplasm and mitochondrial inner membrane, which mainly related to ATP binding, catalytic activity and structural molecular activity. In total of 51 uniquely expressed proteins (21 in WP, 23 in WL and 7 in PM), associated with multiple key signaling pathways, including Rap1, cGMP-PKG, PI3K-Akt, Wnt and HIF-1, etc., relevant to treating cardiovascular diseases, diabetes, cancer and even a variety of neurodegenerative diseases. Three proteins with potential bioactivities, including Neurohemerythrin, Hirudin and Eglin C, were selected as the quality makers and then quantified based on the characteristic peptides.

CONCLUSIONS

This work profiled the proteome of three species of leeches, and addressed potential active proteins of the medicinal leech, which would help to provide the potential molecular mechanisms involved in disease treatment. The proteomics-based approach developed in this work is not only useful for the discovery of proteins with potential bioactivities but also helpful for the bioactivity relevant quality control of animal medicines.

[Cloning and expression analysis of wpHSP90 gene from Whitmania pigra at different temperatures]

HSP90 is a widely distributed molecular chaperone that participates in a variety of cellular processes and plays an important role in the meiosis of germ cells. However, its role in the gonadal development of hermaphroditic Whitmania pigra is not yet clear. To explore the effect of HSP90 on the germ cell development of Wh. Pigra, this study cloned the wpHSP90 gene, performed bioinformatics analysis, and measured its expression levels. The results showed that the cloned wpHSP90 was 2 592 bp in length, with an open reading frame(ORF) of 2 373 bp, encoding 790 amino acids. Prediction analysis revealed 85 phosphorylation modification sites on serine, threonine, and tyrosine residues of the wpHSP90 protein. Structural domain prediction and multiple sequence alignment results showed that wpHSP90 contained two conserved domains of HSP90 and exhibited the highest homology with Helobdella robusta, with a sequence similarity of 80.72%. RT-qPCR results showed that the relative expression level of wpHSP90 in the gonads of 5-month-old Wh. pigra was positively correlated with temperature within the range of 12 ℃ to 28 ℃. The expression level in the female gonads was significantly higher than in the male gonads and correlated with the trend of germ cell development in the ovaries and testes. In conclusion, wpHSP90 may be involved in regulating the development of germ cells, particularly oocytes, in Wh. pigra. This study provides a reference for further research on the gonadal development mechanism in Wh. pigra.

[Effect of heavy metal lead on anticoagulant activity of leech based on label-free quantitative proteomics]

Whitmania pigra is the most widely distributed species of leeches in the market. In this study, the effect of heavy metal lead pollution on the anticoagulant activity of Wh. pigra was studied and the potential mechanism was explored. Pb(NO_3)_2 was used to contaminate the breeding soil which was then used to rear Wh. pigra for 50 days(lead-contaminated group, LC group), and meanwhile the blank control group(CG group) was set. Proteins were extracted from the obtained leech samples, and the differentially expressed proteins between LC and CG groups were analyzed by label-free proteomics technology. In this study, a total of 152 differentially expressed proteins were screened out, of which 93 proteins were up-regulated and 59 proteins were down-regulated in LC group. Bioinformatics analysis showed that the biological processes enriched with the differentially expressed proteins were mainly vesicle-mediated transport and transport positive regulation; the enriched cell components were mainly endocytosis vesicles and apical plasma membrane; the enriched molecular functions mainly included carbohydrate binding. The differentially expressed proteins were enriched in 76 KEGG pathways, which mainly involved metabolic pathways, biosynthesis of secondary metabolites, and bacterial invasion of epithelial cells. In this study, two differentially expressed proteins with Antistasin domain were presumed, which provides reference for further exploring the regulatory mechanism and signal transduction underlying the effect of lead pollution on the anticoagulant activity of leech.

WPK5, a Novel Kunitz-Type Peptide from the Leech Whitmania pigra Inhibiting Factor XIa, and Its Loop-Replaced Mutant to Improve Potency

Kunitz-type proteins or peptides have been found in many blood-sucking animals, but the identity of them in leeches remained elusive. In the present study, five Kunitz-type peptides named WPK1-WPK5 were identified from the leech Whitmania pigra. Recombinant WPK1-WPK5 were expressed in Pichia pastoris GS115, and their inhibitory activity against Factor XIa (FXIa) was tested. WPK5 showed inhibitory activity against FXIa with an IC₅₀ value of 978.20 nM. To improve its potency, the loop replacement strategy was used. The loop 1 (TGPCRSNLER) and loop 2 (QYGGC) in WPK5 were replaced by loop 1 (TGPCRAMISR) and loop 2 (FYGGC) in PN2KPI, respectively, and the resulting peptide named WPK5-Mut showed an IC₅₀ value of 8.34 nM to FXIa, which is about 100-fold the potency of FXIa compared to that of WPK5. WPK5-Mut was further evaluated for its extensive bioactivity in vitro and in vivo. It dose-dependently prolonged APTT on both murine plasma and human plasma, and potently inhibited FeCl₃-induced carotid artery thrombosis in mice at a dose of 1.5 mg/kg. Additionally, WPK5-Mut did not show significant bleeding risk at a dose of 6 mg/kg. Together, these results showed that WPK5-Mut is a promising candidate for the development of an antithrombotic drug.

[Effects of Wp-PKC on gonadal development of Whitmania pigra]

Protein kinase C(PKC) is a kind of kinase which is widely involved in cell proliferation and development. PKC(Wp-PKC) in Whitmania pigra body belongs to classic PKC. In order to investigate the effect of Wp-PKC on the development of Wh. pigra germ cells, 17β-estradiol(17β-E2)(100 ng·mL~(-1)) and methyltestosterone(MT)(150 μg·L~(-1)), 150 μg·L~(-1)(MT)+0.5 mg·L~(-1) PKC, 0.5 mg·L~(-1) PKC inhibitor were added to Wh. pigra culture water, and no addition group(control group) was added, and the effects on the development of Wh. pigra germ cells and the expression of Wp-PKC were observed. The results showed that: Wp-PKC in male gonads was always higher than that in female gonads; MT promoted the development of male gonads in Wh. pigra, while the expression of Wp-PKC was significantly higher than that in the control; 17β-E2 promoted the development of female gonads in Wh. pigra and Wp-PKC expression significantly lower than that of the control; while the development of the female and male gonads in the PKC inhibitor group was inhibited, the expression of Wp-PKC was significantly lower than that of the control. In summary, Wp-PKC may promote the development of Wh. pigra, especially the development of male gonads.

[Cloning and expression analysis of protein kinase C gene from Whitmania pigra]

Protein kinase C(PKC) is a type of protein kinase widely involved in cell proliferation and development, but the developmental mechanism in the gonads of androgynous animals is still unclear. In order to explore the role of protein kinase C in the development of Whitmania pigra germ cells, the Wh. pigra PKC(Wp-PKC) gene was cloned, bioinformatics analysis was conducted, and fluorescent quantitative PCR was used to analyze the expression of female and male gonads. The results showed that:(1)The cloned Wp-PKC had a full length of 2 580 bp, a relative molecular weight of 76 555.19, and contains an open reading frame encoding 670 amino acids, Wp-PKC was closely related to Danio rerio PKC-α and rat PKC-γ. The similarity of amino acid sequence was 55% and 58%.(2)The protein encoded by Wp-PKC had no signal peptide and was a hydrophilic protein. The secondary structure is mainly composed of random coils, α-helices, extended chains, folds and folds, with the largest proportion of random coils and α-helices. Wp-PKC protein does not contain a transmembrane domain. Multiple sequence alignment and domain prediction analysis show that Wp-PKC contains 4 conserved domains of classical protein kinase C.(3)Fluorescence quantitative results showed that the expression of Wp-PKC in Wh. pigra gonads was positively correlated with the development of germ cells, and the expression in male gonads was significantly higher than that in female gonads. In summary, Wp-PKC is a classic PKC, and Wp-PKC may promote the development of Wh. pigra, especially the development of male gonads, and provide references for further research on the developmental mechanisms of Wh. pigra.

Proteome and phosphoproteome profiling reveals the regulation mechanism of hibernation in a freshwater leech (Whitmania pigra)

Hibernation is an energy-saving and adaptive strategy adopted by leech, an important medicinal resource in Asia, to survive low temperature. Reversible protein phosphorylation (RPP) plays a key role in the regulation of mammalian hibernation processes but has never been documented in freshwater invertebrate such as leech. In this study, we detected the effects of hibernation on the proteome and phosphoproteome of the leech Whitmania pigra. A total of 2184 proteins and 2598 sites were quantified. Deep-hibernation resulted in 85 up-regulated and 107 down-regulated proteins and 318 up-regulated and 204 down-regulated phosphosites using a 1.5-fold threshold (P<0.05). Proteins involved in protein digestion and absorption, amino acid metabolism and N-glycan biosynthesis were significantly down-regulated during deep-hibernation. However, proteins involved in maintaining cell structure stability in hibernating animals were up-regulated. Differentially phosphorylated proteins provided the first global picture of a shift in energy metabolism, protein synthesis, cytoprotection and signaling during deep hibernation. Furthermore, AMP-activated protein kinase and protein kinase C play major roles in the regulation of these functional processes. These data significantly improve our understanding of the regulatory mechanisms of leech hibernation processes and provides substantial candidate phosphorylated proteins that could be important for functionally adapt in freshwater animals. SIGNIFICANCE: The leech Whitmania pigra as an important medicinal resource in Asia is an excellent model freshwater invertebrate for studies of environmentally-induced hibernation. The present study provides the first quantitative proteomics and phosphoproteomic analysis of leech hibernation using isobaric tag based TMT labeling and high-resolution mass spectrometry. These data significantly improve our understanding of the regulatory mechanisms when ectotherm animals face environmental stress and provides substantial candidate phosphorylated proteins that could be important for functionally adapt in freshwater animals.

[Effects of constant temperature on growth and gonad development of overwintering Whitmania pigra]

The present study was conducted to explore the effect of constant temperature overwintering on the growth, gonadal development and internal quality of the Wh. pigra which were in overwintering period. Wh. pigra which in overwintering period were placed in light incubator at 21 ℃, and the Wh. pigra that overwintered under natural conditions were used as control. That the changes of growth performance, gonad index, internal quality of two groups of Wh. pigra were measured at the end of the overwintering. Simultaneously the tissue slice technique was used to observe the morphological structure of the spermary and ovary of the two groups. The results showed that the body weight of constant temperature overwintering Wh. pigra which were placed in light incubator at 21 ℃ was 2.35 times that of natural overwintering Wh. pigra which overwintered under natural conditions, and the weight of female gonads of the Wh. pigra which were placed in light incubator at 21 ℃ was 11.54% higher than that of Wh. pigra which overwintered under natural conditions, and the weight of male gonads of the Wh. pigra which were placed in light incubator at 21 ℃ was 48.33% higher than that of the Wh. pigra which overwintered under natural conditions. At the same time, that vitellogenesis cells and film forming cells which in ovarian vesicles were significantly higher than those of the Wh. pigra which overwintered under natural conditions, and that spermatogonia and primary spermatocytes which in seminal vesicle were significantly higher than those of Wh. pigra which overwintered under natural conditions. Most important of all, the anti-thrombin activity of Wh. pigra which were placed in light incubator at 21 ℃ increased by 27.85% compared with the Wh. pigra that overwintered under natural conditions. In conclusion, that constant temperature can promote the growth, the development of sperm and egg cells, and the increase of anti-thrombin activity of Wh. pigra which were in overwintering period.

[Effect of lead pollution on anticoagulant effect of Whitmania pigra based on in vitro anticoagulation experiment]

Leech has a good anticoagulant activity and is one of the raw materials for treatment of many cardiovascular and cerebrovascular diseases. This study was based on in vitro anticoagulant experiments( APTT and PT) to investigate the effects of lead contamination on the anticoagulant effect of leech. At present,the Hirudo circulating in the market are dominated by Whitmania pigra,therefore Wh. pigra were cultivated under a different lead pollution for 50 days. Then,the effects of Wh. pigra extract,extracting from different cultivating environment,on activated partial thrombin time( APTT) and prothrombin time( PT) were determined by automatic coagulation instrument. The results showed that the Wh. pigra extract significantly prolonged the APTT compared with the saline group.The APTT of the lead-high residual Wh. pigra was shorter than that of the blank Wh. pigra. The Wh. pigra extracts from different treatment groups had little effect on PT. The results showed that the lead residue in the Wh. pigra increased with the increase of lead in the cultured soil,the lead residual of the Pb-H group was( 10. 66±2. 79) mg·kg~(-1),which exceeded the lead limit specified in the 2015 edition of the Chinese Pharmacopoeia. The results indicated that growth environment pollution is one of the important factors causing excessive lead in Wh. pigra. Lead pollution will reduce the anticoagulant effect of Wh. pigra and affect its clinical efficacy.

[Effects of MT on growth and gonad development of natural overwintering Whitmania pigra]

The objectives of study were to explore the effects of exogenous methyltestosterone( MT) on the growth and gonadal development of overwintering Whitmania pigra. Before overwintering,0. 1,1. 0,10. 0,100. 0,150. 0 μg·L^-1 of MT were added to the aquaculture water for 6 weeks. The changes of growth performance,gonad index,endogenous steroid hormones level and internal quality were measured after hibernate for 60 days. Then the tissue slice technique was used to observe the spermary( ovary) of Wh. pigra.The results showed that the body weight,survival rate and gonadal index increased first and then decreased with the increase of exogenous MT concentration; the male gland index was found the highest at the concentration of MT 10. 0 μg·L^-1 and the female gland index was the highest at the concentration of MT 1. 0 μg·L^-1. The survival rate of Wh. pigra peaked at the concentration of MT 10. 0 μg·L^-1.The weight reaches a peak at a concentration of MT 100. 0 μg·L^-1( P<0. 05). The number of primary spermatocytes in the testis was negatively correlated with the concentration of exogenous MT. The number of secondary spermatocytes and sperm cells increased first and then decreased. The concentration of secondary spermatocytes was the highest when the concentration of MT was 100. 0 μg·L^-1.The number and volume of oocytes in the ovary and the yolk granules increased first and then decreased with the increase of exogenous MT concentration,and the highest was observed at the MT concentration of 100. 0 μg·L^-1. The endogenous steroid hormone of Wh.pigra increased first and then decreased with the increase of exogenous MT concentration. The concentration of androgen and progesterone was the highest in MT 100. 0 μg·L^-1 treatment( P<0. 05),and the concentration of estrogen was found the highest in MT 10. 0 μg·L^-1 treatment( P<0. 05). After adding exogenous MT,Wh. pigra moisture content,acid-insoluble ash content,p H and anti-thrombin activity met the quality criterion of medicinal Wh. pigra in Chinese Pharmacopoeia( 2015 edition). In conclusion,the short-term addition of 1. 0-100. 0 μg·L^-1 exogenous MT before hibernation can promote the growth,the development of sperm cells and the antithrombin activity of Wh. pigra.

[Effects of 17β-E2 on growth and gonad development of overwintering Whitmania pigra]

The present study was conducted to explores the effects of short-term addition of 17β-E2 on the growth,gonad development and internal quality of overwintering Whitmania pigra. Before overwintering,0. 0,1. 0,10. 0,25. 0,50. 0,100. 0 μg·L~(-1) of 17β-E2 were added to the aquaculture water for 6 weeks and then hibernated for 60 days. The changes of growth performance,gonad index,morphological structure of spermary( ovary),endogenous steroid hormones level and internal quality were measured. The results showed that the body weight,weight gain rate,specific growth rate,female gonad index,oocyte development and endogenous estrogen level of the leech increased first and then decreased with the increase of the concentration of exogenous 17β-E2,which were higher than those of the control group. The body weight,weight gain rate and specific growth rate of the leech at the concentration of 25 μg·L~(-1)17β-E2 were significantly higher than those of the other groups( P<0. 05),oocyte development and endogenous estrogen levels were significantly higher than those of other groups at the concentration of 50 μg·L~(-1)( P<0. 05). When the concentration of exogenous 17β-E2 was higher than 50 μg·L~(-1),the levels of male gonad index,spermatocyte development,endogenous androgen and progesterone were significantly inhibited( P< 0. 05). There was no significant difference in endogenous corticosteroid levels among the groups. In conclusion,short-term addition of exogenous 17β-E2 of 10-25 μg·L~(-1) could promote the growth of overwintering leeches,oocyte development and antithrombin activity without inhibiting the development of male gonads.

[Cloning of Guamerin gene in Whitmania pigra and its spatio-temporal expression analysis after ingestion]

The present study cloned wpGuamerin gene from a non-bloodsucking leech (Whitmania pigra), and the bioinformatics analysis of the sequence was performed. Additionally, the effects of feeding duration on the expression profile of the wp Guamerin gene were explored. The results showed that its sequence consisted of 295 nucleotides encoding a peptide of 83 amino acids(Genbank: KX768545), and its relative molecular weight is 9 145.95 Da. wp Guamerin does not encode proteins with a signal peptide, belonging to the hydrophilic protein. Its secondary structure is mainly composed of α-helix, extending chain, folding and random curl. Its similarity with other blood-sucking leeches ranges from 29% to 65%. The results revealed that wpGuamerin mRNA was detected higher expression in muscle than in salivary glands of Wh. pigra, and did not expressed in ingluvies and intestine. Its expression in muscle and salivary glands showed a single peak curve after feeding and the peak was observed in the 1st and 3rd after feeding, respectively. In summary, wp Guamerin in Wh. pigra is a small molecule polypeptide protein and is different from the Guamerin in blood-sucking leeches. wpGuamerin does not express in the digestive tract of Wh. pigra, and mainly express in muscle. Feeding behavior would stimulate the expression of wpGuamerin gene in muscle and salivary glands, but not in digestive tract.

[Effect of Astragali Radix on growth, immunity and related gene expression of Whitmania pigra]

To explore the effect and mechanism of Astragali Radix on growth and immunity of Whitmania pigra, 0, 0.01%, 0.03%, 0.05%, 0.07%, 0.09% of Astragali Radix were added to the daily feeding of Wh. pigra. After 60 days of feeding, the growth performance, activities of digestive enzyme and anti-reverse enzyme, inner quality, the expression levels of GH, IGF-1 and digestive enzyme-related genes were measured. Meanwhile, the effects of heat stress on the living conditions of Wh. pigra were observed and counted, and the expression levels of HSP70 and immune related genes were measured. The results showed that the final weight, weight gain rate, specific growth rate, activities of digestive enzyme and anti-reverse enzyme, the expression levels of GH, IGF-1 and digestive enzyme-related genes in the Astragali Radix group were higher than those in the control group, and with the increase of Astragali Radix concentration, the above-mentioned indexes increased initially and then decreased, and significantly higher in the 0.05% of Astragali Radix group than in the other groups (P<0.05). There was no significant difference in the inner quality of Wh. pigra between the Astragali Radix and control groups. The survival rate of Wh. pigra was negatively correlated with heat stress treatment duration. With the prolongation of heat stress treatment duration, the expression levels of HSP70 and immune related genes were increased first and then decreased, and peaked at 24 h. The survival rate and the expression levels of HSP70 and immune related genes in the Astragali Radix group were higher than those in the control group, and was significantly higher in the 0.05% of Astragali Radix group than in the other groups (P<0.05). In conclusion, Astragali Radix can increase the activities of digestive enzyme and anti-reverse enzyme, the expression levels of related genes, growth performance, and immunity to heat stress of Wh. pigra. It is suggested to add 0.05% of Astragali Radix in the actual production of Wh. pigra to improve the production profit.

[Effect of ingestion on antithrombin activity in different tissues of Whitmania pigra]

To study the effects of ingestion on antithrombin activities in different tissues of Whitmania pigra, the salivary glands, ingluvies, intestine and muscle of adult leeches were weighted on the 1st d, 3rd d, 5th d, 7th d and 11th d after feeding, respectively, and meanwhile antithrombin activity was measured by antithrombin titration method. The results showed that the antithrombin activity of salivary glands in different stages was significantly higher than that in other tissues (P<0.05). The activity of antithrombin in muscle tissue increased initially and then decreased with the prolongation of the time after feeding, and the peak was observed on the 5th day after feeding (P<0.05). The activity of antithrombin in the salivary glands, gluvies and intestine were found the highest on the 1st day after feeding(P<0.05), and then gradually decreased with the prolongation of the time of stopping the diet. The total amount of antithrombin activity on the 5th day was increased by 49.5%, 73.5%, 69.1% and 126.0% comparing with the 1st, 3rd, 7th and 11th day after feeding, respectively (P<0.05). In summary, both the feeding behavior and the food can induce the secretion of anticoagulant substances in the salivary glands and the digestive tract. The total amount of antithrombin activity was the highest on the 5th day after feeding and the 5th day after feeding was suggested as harvesting time.

Leeches attenuate blood hyperviscosity and related metabolic disorders in rats differently than aspirin

ETHNOPHARMACOLOGICAL RELEVANCE

Whitmania pigra Whitman (Whitmania pigra, WP), firstly recorded in the Shennong's Herbal Classic and officially listed in the Chinese Pharmacopoeia, is a well-used cardiovascular protective traditional Chinese medicine derived from leeches. Traditional Chinese physicians prefer to prescribe the dried whole body of leech processed under high temperatures. It has been reported that dried WP remains clinically effective. However, the therapeutic mechanism has yet not be clearly elucidated.

AIM OF THE STUDY

This study was designed to investigate the protective activity of the extract of WP in a high-molecular-weight dextran-induced blood hyperviscosity rat model, and to explore the role of WP in improving blood hyperviscosity related metabolic disorders and to clarify the possible mechanism of metabolic regulation.

MATERIALS AND METHODS

The hemorheological parameters were measured with an automated blood rheology analyzer. Hematoxylin-eosin staining was used to observe the pathological changes in aortic tissues samples. Further, a liquid chromatography-mass-spectrometry (LC-MS)-based untargeted metabolomics approach was applied to characterize the metabolic alterations.

RESULTS

WP has evident attenuating effects on blood hyperviscosity and related metabolic disorders, and the influences are distinct from those of aspirin. The results showed that WP had good effects in reducing blood viscosity and ameliorating histopathological changes in the thoracic aorta in a high molecular weight dextran-induced blood hyperviscosity rat model. The middle dose (2.5 g raw material/kg body weight) of WP exhibited effects equivalent to aspirin (100 mg/kg) on hemorheological and histopathological parameters (P > 0.05). However, when using metabolomics profiling, we found that WP could significantly improve blood hyperviscosity-related metabolic disorders and restore metabolites to normal levels; while aspirin showed little effect. With principal component analysis and orthogonal partial least-squares discriminant analysis, WP regulated many more endogenous metabolites than aspirin. With pathway enrichment analysis, the differential endogenous metabolites were involved in cysteine and methionine metabolism, TCA cycle, arachidonic acid metabolism, etc., highlighting the metabolic reprogramming potential of WP against blood hyperviscosity-induced metabolic disorders.

CONCLUSIONS

The study suggest that WP has a more potent effect, but a different mechanism, than aspirin in improving either blood hyperviscosity or related metabolic disorders associated with cardio- and cerebrovascular diseases.

Transcriptomics and differential gene expression in Whitmania pigra (Annelida: Clitellata: Hirudinida: Hirudinidae): Contrasting feeding and fasting modes

The medicinal utility of leeches has been demonstrated through decades of use in modern hospital settings, mainly as relievers of venous congestion following flap or digit replantation surgery. In the present study, we sequence and annotate (through BLAST- and Gene Ontology-based approaches) the salivary transcriptome of the nonblood feeding hirudinid Whitmania pigra and assess the differential gene expression of anticoagulation factors (through both quantitative real-time PCR [qRT-PCR] and in silico-based methods) during feeding and fasting conditions. This was done in order to evince the diversity of putative anticoagulation factors, as well as estimate the levels of upregulation of genes immediately after feeding. In total, we found sequences with demonstrated orthology (via both phylogenetic analyses and BLAST-based approaches) to seven different proteins that have previously been linked to anticoagulatory capabilities-eglin C, bdellin, granulin, guamerin, hyaluronidase, destabilase I, and lipocalin. All of these were recovered from leeches both in the fasting and in the feeding conditions, but all show signs of upregulation in the feeding leeches. Interestingly, our RNA-seq effort, coupled with a hypergeometric test, indicated that the differentially expressed genes were disproportionately involved in three main immunological pathways (endocytosis, peroxisome regulation, and lysosome regulation). The results and implications of the finding of anticoagulants in this nonblood feeding leech and the putative upregulation of anticoagulation factors after feeding are briefly discussed in an evolutionary context.

[In vitro anticoagulant activity of different processed products of Whitmania pigra by water extraction and bionic extraction]

In order to determine the scientificalness of traditionally processed Whitmania pigra, water extraction method and bionic extraction method were used respectively to extract the anticoagulating active components in W. pigra hanging dry products, talcum powder fried products and wine immersing-baked products. Activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), and antithrombin activity were selected as the activity indexes to evaluate the anticoagulant activities of different processed W. pigra. Then the contents of protein in different processed W. pigra were measured by Coomassie brilliant blue method to preliminarily explain the reason of anticoagulant activity changes. When water extraction method was used, the results of APTT, PT, TT and antithrombin activity showed that the anticoagulant activities of W. pigra were decreased both in talcum powder fried products and wine immersing-baked products, and the activity order was as follows: hanging dried products> wine immersing-baked products>talcum powder fried products. This order was same as the protein content order. While when bionic extraction was used, APTT was shortened in talcum powder fried products, but all the other results indicated the anticoagulant activities of W. pigra processed products were increased, and the activity order was as follows: wine immersing-baked products>talcum powder fried products>hanging dry products. As compared with water extraction, the bionic extraction was more similar to the absorption process of W. pigra in human digestive system after oral administration and was more scientific. Therefore, the traditional processing method can not only modify the taste and smell, but also enhance the anticoagulant activity of W. pigra.

[Histological study of annual cycle of gonad and germ cell development of Whitmania pigra]

The reproductive system and gonad development and germ cell occurrence of Whitmania pigra have been studied by using tissue section electron microscope techniques. W. pigra has completely independent male and female reproduction system, which lasts 11 months. The development of spermary started before the development of ovary. When egg cell is only a primordial germ cell, sperm has an initially complete form. Meanwhile, sperm cells and egg cells orderly development and synchronously mature. According to the development of sperm cells and egg cells, the development of cycle of the spermary could be divided into 6 stages: proliferating stage (1-3 months of age), growing stage (4-5 months of age), resting stage (6-8 months of age), maturing stage (9 months of age), spawning stage (10 months of age) and degradation stage (11 months of age). The development of cycle of the ovary could be divided into 6 stages: forming stage (1-2 months of age), proliferating stage (3-4 months of age), growing stage (5-8 months of age), maturing stage (9 months of age), spawning stage (10 months of age) and resting stage (11 months of age). W. pigra is a synchronous hermaphrodite animal, the development of cycle of the spermary and ovary each has six stages, sperm cells and egg cells orderly development and synchronously mature.

[Study on correlation of oxygen consumption rate and suffocation point of Whitmania pigra and Bellamya purificata and optimum way of feeding Whitmania pigra]

The oxygen consumption, oxygen consumption rate and suffocation point of different quality Whitmania pigra and Bellamya purificata were determined by hydrostatic breathing room method. The effects of feeding modes on growth of W.pigra were determined by biomass. The results showed that the oxygen consumption correlated positively with the weight of W.pigra and B. purificata（P<0.05）, suffocation point increased with the increases of the weight（P<0.05）.Oxygen consumption correlated negatively with the weight of W. pigra, the oxygen consumption rate of B.purificata first increased and then decreased with the increasing of the weight. Feeding modes had no significant effects on the finial weight, SGR, WGR, death rates of W. pigra. Feeding modes had significant effects on eating ratio. It suggested that the optimum feeding frequency of W. pigra was once every three days. Scientific and reasonable feeding amount of B. purificata should be calculated based on oxygen consumption and suffocation point of W.pigra and B.purificata at every period. Meanwhile, stocking density, water area and water exchanging frequency should be taken into consideration.

Genetic variation in Whitmania pigra, Hirudo nipponica and Poecilobdella manillensis, three endemic and endangered species in China using SSR and TRAP markers

Leeches are not only important medicinal animals worldwide but also are endangered. We aimed to (i) explore the level of genetic diversity within/among populations of three leeches, (ii) assess genetic differentiation among these three leeches, and (iii) discuss an appropriate strategy for conserving leech germplasm. A total of 315 individuals of Whitmania pigra, Hirudo nipponica and Poecilobdella manillensis from 21 populations were collected in China and Vietnam. The genetic structure and genetic diversity among and within the 21 populations were evaluated using target region amplified polymorphism (TRAP) and simple sequence repeat (SSR) markers. Sixteen pairs of TRAP primers generated a total of 398 fragments, of which 396 (99.50%) were polymorphic; fourteen pairs of SSR primers generated a total of 60 fragments, of which 59 (98.33%) were polymorphic. Shannon's index (I) and Nei's gene diversity index (H) for the three leeches were high at the species level (I=0.4980 and H=0.3323 for TRAPs, I=0.4487 and H=0.2969 for SSRs in W. pigra; I=0.4147/0.3769, H=0.2788/0.2566 for H. nipponica; and I=0.4616/0.4717, H=0.3099/0.3203 for P. manillensis). However, low genetic diversity was determined at the population level; the average genetic diversity measures within populations were H=0.1767/0.1376, I=0.2589/0.2043 for W. pigra, H=0.2149/0.2021, I=0.3184/0.3000 for H. nipponica and H=0.2850/0.2724, I=0.4152/0.3967 for P. manillensis. We conclude that there was limited gene exchange within/among populations and species, as the gene flow number (Nm) was 0.5493/0.5807. However, for all three species, the genetic diversity was different at the population level. Gene differentiation (Gst) and Nm were 0.4682 /0.5364 and 0.5678/0.4321 for W. pigra, 0.2294/0.2127 and 1.6797/1.8512 for H. nipponica and 0.1214/0.1496 and 3.6202/2.8412 for P. manillensis. STRUCTURE analysis, Unweighted Pair-Group Method with Arithmetic means (UPGMA) cluster analysis and Principal Coordinates Analysis (PCOA) all yielded similar results. The isolation-by-distance pattern was not significant for any of the three species by the Mantel test. These data emphasize the need for management, conservation, and rehabilitation of this animal species. Finally, an appropriate strategy for conserving leech is proposed.