Exposure to Gynura japonica (Thunb.) Juel plants induces hepatoxicity in rats and Buffalo rat liver cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Gynura japonica (Thunb.) Juel is often confused with the non-pyrrolizidine alkaloid-producing herbs, Tu-San-Qi (Sedum aizoon L.) and San-Qi (Panax notoginseng L.), due to similarities in name, appearance, and medicinal use. It contains pyrrolizidine alkaloids, which cause over 50% of cases of hepatic sinus obstruction syndrome. However, the mechanisms underlying G. japonica-induced hepatotoxicity remain poorly understood. AIM OF THE STUDY: In this study, we aimed to investigate the toxic effects of a G. japonica decoction on liver and Buffalo rat liver (BRL) cells and elucidate the associated mechanisms. MATERIALS AND METHODS: This study employed G. japonica decoction and examined its effects on liver function and tissue damage in Sprague-Dawley rats. Bioinformatics analysis was employed to identify gene expression and enriched pathways related to hepatotoxicity. Laser scanning confocal microscopy and flow cytometric annexin V/PI labeling assays were utilized to observe apoptosis in BRL cells induced by G. japonica. Transmission electron microscopy and JC-1 staining were used to determine the effects of G. japonica on mitochondrial ultrastructure and membrane potential in BRL cells. The bicinchoninic acid method and enzyme-linked immunosorbent assays were used to detect the expression of apoptosis-related proteins and caspase-3 activity, respectively. RESULTS: Comparisons of body weight, liver histopathology, and serum liver function-related indices in rats, t showed that exposure to G. japonica may cause liver damage. Bioinformatics analysis indicated that hepatotoxicity might be related to apoptotic signaling pathways, the positive regulation of programmed cell death, and responses to toxic substances. BRL cells exposed to the G. japonica decoction exhibited mid-to late-stage apoptosis and necrosis, along with alterations in mitochondrial morphology and membrane potential. Furthermore, expression of cytochrome C (Cyt C) and pro-apoptotic proteins was increased, anti-apoptotic proteins decreased, and caspase-3 activity elevated. CONCLUSIONS: These findings indicate that G. japonica-induced hepatotoxicity involves the activation of mitochondria-mediated apoptosis. Our research enhances the scientific and theoretical foundation for clinical therapy and improves public awareness of the potential toxicity of herbal remedies.

Phenotypic assessment of Cox10 variants and their implications for Leigh Syndrome.

OBJECTIVES: Cox10 is an enzyme required for the activity of cytochrome c oxidase. Humans who lack at least one functional copy of Cox10 have a form of Leigh Syndrome, a genetic disease that is usually fatal in infancy. As more human genomes are sequenced, new alleles are being discovered; whether or not these alleles encode functional proteins remains unclear. Thus, we set out to measure the phenotypes of many human Cox10 variants by expressing them in yeast cells. RESULTS: We successfully expressed the reference sequence and 25 variants of human Cox10 in yeast. We quantitated the ability of these variants to support growth on nonfermentable media and directly measured cytochrome c oxidase activity. 11 of these Cox10 variants supported approximately half or more the cytochrome c oxidase activity compared to the reference sequence. All of the strains containing those 11 variants also grew robustly using a nonfermentable carbon source. Cells expressing the other variants showed low cytochrome c oxidase activity and failed to grow on nonfermentable media.

Omega-3 fatty acids abrogates oxido-inflammatory and mitochondrial dysfunction-associated apoptotic responses in testis of tamoxifen-treated rats.

Background: Tamoxifen (TAM) is a widely used drug in patients with gynecomastia and breast cancer. TAM exerts its anticancer effects via its antiestrogenic activities. Unfortunately, TAM has been reported to exert gonadotoxic effects on male testes. Therefore, this study was designed to explore the possible associated mechanisms involved in TAM-induced testicular dysfunction and the possible ameliorative effects of omega-3 fatty acids (O3FA). Methodology: Animals were randomly divided into control, O3FA, TAM, and TAM + O3FA. All treatment lasted for 28 days. Results: TAM exposure impaired sperm qualities (count, motility, and normal morphology) and decreased testicular 3ß-HSD and 17ß-HSD. It was accompanied by a decline in serum testosterone and an increase in estradiol, luteinizing and follicle-stimulating hormones. These observed alterations were associated with an increase in testicular injury markers, oxido-inflammatory response, and mitochondria-mediated apoptosis. These observed alterations were ameliorated by O3FA treatments. Conclusions: O3FA ameliorated TAM-induced testicular dysfunction in male Wistar rats by modulating XO/UA and Nrf2/NF-kb signaling and cytochrome c-mediated apoptosis in TAM-treated rats.

New report of the rare Sciadonus alphacrucis Melo et al., 2022 (Teleostei, Ophidiiformes, Bythitidae), DNA barcoding, and range extension in the western South Atlantic.

Sciadonus alphacrucis Melo, Gomes, Møller & Nielsen, 2022 is a rare deep-sea species, previously known from only two specimens collected off São Paulo State, southeastern Brazil, in the western South Atlantic. Herein, we report a new specimen of S. alphacrucis collected on the continental slope off Santa Catarina State, southern Brazil, thereby extending its known distribution by 420 km. Additionally, we provide the new meristic and morphometric data, the molecular identification using sequences of the cytochrome c oxidase subunit I (COI), an updated distribution map, and a discussion of troglomorphic traits.

Phytochemical Composition and Bioactivities of Some Hydrophytes: Antioxidant, Antiparasitic, Antibacterial, and Anticancer Properties and Mechanisms.

Few researches have explored the production of pharmaceuticals from aquatic plants. Therefore, this study explored, for the first time, the phytochemical composition and bioactivities of ten aquatic plants. Aquatic plant shoots from various Nile River canals were collected, dried, and ground for aqueous extract preparation. Phytochemical composition and antioxidant capacity were assessed using DPPH assays. Extracts were tested for antiparasitic, antibacterial, anti-biofilm, and anticancer activities through standard in vitro assays, measuring IC50 values, and evaluating mechanisms of action, including cell viability and high-content screening assays. The results showed that the aquatic plants were rich in pharmaceutical compounds. The antioxidant capacity of these extracts exceeded that of vitamin C. The extracts showed promising antiparasitic activity against pathogens like Opisthorchis viverrini and Plasmodium falciparum, with IC50 values between 0.7 and 2.5 µg/mL. They also demonstrated low MICs against various pathogenic bacteria, causing DNA damage, increased plasma membrane permeability, and 90% biofilm inhibition. In terms of anticancer activity, extracts were effective against a panel of cancer cell lines, with Ludwigia stolonifera exhibiting the highest efficacy. Its IC50 ranged from 0.5 µg/mL for pancreatic, esophageal, and colon cancer cells to 1.5 µg/mL for gastric cancer cells. Overall, IC50 values for all extracts were below 6 µg/mL, showing significant apoptotic activity, increased nuclear intensity, plasma membrane permeability, mitochondrial membrane permeability, and cytochrome c release, and outperforming doxorubicin. This study highlights the potential of aquatic plants as sources for new, safe, and effective drugs with strong antiparasitic, antibacterial, and anticancer properties.

Resonance Raman spectral analysis of the heme site structure of cytochrome c oxidase with its positive regulator CHCHD2.

Cytochrome c oxidase (CcO) reduces O2, pumps protons in the mitochondrial respiratory chain, and is essential for oxygen consumption in the cell. The coiled-coil-helix-coiled-coil-helix domain-containing 2 (CHCHD2; also known as mitochondrial nuclear retrograde regulator 1 [MNRR1], Parkinson's disease 22 [PARK22] and aging-associated gene 10 protein [AAG10]) is a protein that binds to CcO from the intermembrane space and positively regulates the activity of CcO. Despite the importance of CHCHD2 in mitochondrial function, the mechanism of action of CHCHD2 and structural information regarding its binding to CcO remain unknown. Here, we utilized visible resonance Raman spectroscopy to investigate the structural changes around the hemes in CcO in the reduced and CO-bound states upon CHCHD2 binding. We found that CHCHD2 has a significant impact on the structure of CcO in the reduced state. Mapping of the heme peripheries that result in Raman spectral changes in the structure of CcO highlighted helices IX and X near the hemes as sites where CHCHD2 takes action. Part of helix IX is exposed in the intermembrane space, whereas helix X, located between both hemes, may play a key role in proton uptake to a proton-loading site in the reduced state for proton pumping. Taken together, our results suggested that CHCHD2 binds near helix IX and induces a structural change in helix X, accelerating proton uptake.

Cytochrome c Oxidase Influences Pyraclostrobin Sensitivity in Fusarium graminearum by Regulating FgAox Through Transcription Factors FgAod2 and FgAod5.

Cytochrome c oxidase (Cox) is a crucial terminal oxidase in the electron transport chain. In this study, we generated 14 Cox gene deletion or overexpression mutants in Fusarium graminearum. Fungicide sensitivity tests revealed that 11 Cox gene deletion mutants displayed resistance to pyraclostrobin, while 10 overexpression mutants showed hypersensitivity. RNA-Seq and RT-qPCR analyses demonstrated the upregulation of FgAox (alternative oxidase in F. graminearum), FgAod2, and FgAod5 (alternative oxidase deficiency in F. graminearum) in ΔFgCox4-2 and ΔFgCox17-75 mutants. In 11 Cox gene deletion mutants, FgAox expression was significantly upregulated, whereas in 10 Cox gene overexpression mutants, it was significantly downregulated. FgAox overexpression mutants exhibit resistance to pyraclostrobin, while FgAox deletion mutants show hypersensitivity to pyraclostrobin. FgAod2 and FgAod5 were identified as transcription factors for FgAox. Our findings reveal that FgCox influences pyraclostrobin sensitivity by regulating FgAox through FgAod2 and FgAod5. Understanding pyraclostrobin resistance mechanisms in F. graminearum could help develop better fungicide rotation and application strategies to manage resistance and guide the creation of new fungicides targeting different pathways.

Antioxidant and anti-cancer potentials of Ag green-synthesized and encapsulated olive leaves particles on HCT-116 cells.

Water extracts (OLE), whey protein encapsulated extracts (OLE/WPNs), and silver nanoparticles (OLE/Ag-NPs) were prepared from olive leaves of Manzenllie and Picual varieties. These preparations were characterized, and their antioxidant and biological activities on Vero and HCT-116 colorectal cells were assessed. The mechanism of action of the preparations was studied through tumor necrosis factor-α (TNF-α) and cytochrome C oxidase (Cox1) gene expression. OLE/Ag-NPs showed smaller particle sizes (14.23-15.53 nm) than OLE/WPNs (229.83-310.67 nm) and demonstrated lower aggregation due to their high Ƹ-potential of -24.86 to -27.90 mV. None of the preparations affected the viability of Vero cells (IC50 = 192.19-421.01 µg/mL), but they showed cytotoxic effects on HCT-116 cells (IC50 = 50.76-196.54 µg/mL), particularly OLE/WPNs. Moreover, the preparations from the Picual variety (OLE, OLE/WPNs, and OLE/Ag-NPs) showed regulatory effects against colon cancer on treated HCT-116 cells by upregulating Cox1 expression and downregulating TNF-α expression. Consequently, OLE/WPNs and OLE/Ag-NPs could be promising for industrial applications with potential health benefits.

The Increase in the Peroxidase Activity of the Cytochrome C with Substitutions in the Universal Binding Site Is Associated with Changes in the Ability to Interact with External Ligands.

Cytochrome c (CytC), a one-electron carrier, transfers electrons from complex bc1 to cytochrome c oxidase (CcO) in the electron-transport chain. Electrostatic interaction with the partners, complex bc1 and CcO, is ensured by a lysine cluster near the heme forming the Universal Binding Site (UBS). We constructed three mutant variants of mitochondrial CytC with one (2Mut), four (5Mut), and five (8Mut) Lys->Glu substitutions in the UBS and some compensating Glu->Lys substitutions at the periphery of the UBS for charge compensation. All mutants showed a 4-6 times increased peroxidase activity and accelerated binding of cyanide to the ferric heme of CytC. In contrast, decomposition of the cyanide complex with ferrous CytC, as monitored by magnetic circular dichroism spectroscopy, was slower in mutants compared to WT. Molecular dynamic simulations revealed the increase in the fluctuations of Cα atoms of individual residues of mutant CytC compared to WT, especially in the Ω-loop (70-85), which can cause destabilization of the Fe…S(Met80) coordination link, facilitation of the binding of exogenous ligands cyanide and peroxide, and an increase in peroxidase activity. It was found that only one substitution K72E is enough to induce all these changes, indicating the significance of K72 and the Ω-loop (70-85) for the structure and physiology of mitochondrial CytC. In this work, we also propose using a ferro-ferricyanide buffer as a substrate to monitor the peroxidase activity of CytC. This new approach allows us to determine the rate of peroxidase activity at moderate (200 µM) concentrations of H2O2 and avoid complications of radical formation during the reaction.

Intermolecular Electrostatic Interactions in Cytochrome c Protein Monolayer on Montmorillonite Alumosilicate Surface: A Positive Cooperative Effect.

Montmorillonite (MM) crystal nanoplates acquire anticancer properties when coated with the mitochondrial protein cytochrome c (cytC) due to the cancer cells' capability to phagocytize cytC-MM colloid particles. The introduced exogenous cytC initiates apoptosis: an irreversible cascade of biochemical reactions leading to cell death. In the present research, we investigate the organization of the cytC layer on the MM surface by employing physicochemical and computer methods-microelectrophoresis, static, and electric light scattering-to study cytC adsorption on the MM surface, and protein electrostatics and docking to calculate the local electric potential and Gibbs free energy of interacting protein globules. The found protein concentration dependence of the adsorbed cytC quantity is nonlinear, manifesting a positive cooperative effect that emerges when the adsorbed cytC globules occupy more than one-third of the MM surface. Computer analysis reveals that the cooperative effect is caused by the formation of protein associates in which the cytC globules are oriented with oppositely charged surfaces. The formation of dimers and trimers is accompanied by a strong reduction in the electrostatic component of the Gibbs free energy of protein association, while the van der Waals component plays a secondary role.

The repertoire of iron superoxide dismutases from Leishmania infantum as targets in the search for therapeutic agents against leishmaniasis.

Species of Leishmania and Trypanosoma genera are the causative agents of relevant parasitic diseases. Survival inside their hosts requires the existence of a potent antioxidant enzymatic machinery. Four iron superoxide dismutases have been described in trypanosomatids (FeSODA, FeSODB1, FeSODB2, and FeSODC) that hold a potential as therapeutic targets. Nonetheless, very few studies have been developed that make use of the purified enzymes. Moreover, FeSODC remains uncharacterised in Leishmania. In this work, for the first time, we describe the purification and enzymatic activity of recombinant versions of the four Leishmania FeSOD isoforms and establish an improved strategy for developing inhibitors. We propose a novel parameter [(V*cyt. c - Vcyt. c)/Vcyt. c] which, in contrast to that used in the classical cytochrome c reduction assay, correlates linearly with enzyme concentration. As a proof of concept, we determine the IC50 values of two ruthenium carbosilane metallodendrimers against these isoforms.

Molecular identification and phylogenetic relationship of fishes belonging to the Family Danionidae from Brahmaputra Basin, Assam, Northeast India.

BACKGROUD: The Northeast India, being part of two global biodiversity hotspot namely the Indo-Burma and Eastern Himalayan Hotspots supports a wide variety of rich aquatic biodiversity including fishes. The family Danionidae is a widely diverse group inhabiting the upper colder stretches of river although few are abundant in the lower stretches. The persisting similarity in the morphological appearance and body colouration within the members of this family seeks an integrated method to identify the species correctly. METHODS AND RESULTS: In the present study, the mt-DNA barcode was generated for correct identification and confirmation of the species. A total of nine mitochondrial cytochrome c oxidase subunit I gene sequences were generated for each species under the study. The pairwise distance values ranged from 0.09 to 9.11% within species and 9.06-32.71% between species. A neighbour-joining tree was constructed based on the Kimura 2 parameter model. Two major groups were observed where Danioninae formed a sister group to the Chedrinae and Rasborinae. CONCLUSION: The present study is a preliminary work to document and identify the species under the family Danionidae from Brahmaputra basin, Assam, using molecular tools and establish the phylogenetic relationship.

Molecular phylogenetical identification of bear roundworms (Baylisascaris transfuga) derived from wild Japanese black bears (Ursus thibetanus japonicus) around Lake Towada.

The bear roundworm Baylisascaris transfuga has been identified in several host bears (Ursinae). However, limited genetic information is available on the bear roundworm in Japanese populations. This study evaluated the genetic composition of bear roundworms isolated from wild Japanese black bears indigenous to Lake Towada, Japan. First, we conducted genetic and/or molecular phylogenetic analyses based on cytochrome c oxidase subunit II and internal transcribed spacer 2 among Baylisascaris species. These analyses revealed that the identified roundworms were genetically B. transfuga. In addition, the average body size of the obtained roundworms in this study was almost the same as that previously reported for B. transfuga. This study represents an important step in genetic research on the roundworm B. transfuga in Ursinae bears not only from Japan but also from the rest of the world.

Factor defining the effects of tetraalkylammonium chloride on stability, folding, and dynamics of horse cytochrome c.

This article describes the molecular mechanism by which tetraalkylammonium chloride ([R4N]Cl: R- = methyl (Me), ethyl (Et), propyl (Pr),butyl (Bu)) modulates the stability, folding, and dynamics of cytochrome c (Cyt c). Analysis of [R4N]Cl effects on thermal/chemical denaturations, millisecond refolding/unfolding kinetics, and slow CO-association kinetics of Cyt c without and with denaturant providing some significant results: (i) [R4N]Cl decreasing the unfolding free energy estimated by thermodynamic and kinetic analysis of thermal/chemical denaturation curves and kinetic chevrons (Log kobs-[GdmCl]) of Cyt c, respectively (ii) hydrophobicity of R-group of [R4N]Cl, preferential inclusion of [R4N]Cl at the protein surface, and destabilizing enthalpic attractive interactions of [Me4N]Cl and steric entropic interactions of [Et4N]Cl,[Pr4N]Cl and [Bu4N]Cl with protein contribute to [R4N]Cl-induced decrease thermodynamic stability of Cyt c (iii) [R4N]Cl exhibits an additive effect with denaturant to decrease thermodynamic stability and refolding rates of Cyt c (iv) low concentrations of [R4N]Cl (≤ 0.5 M) constrain the motional dynamics while the higher concentrations (>0.75 M [R4N]Cl) enhance the structural-fluctuations that denture protein (v) hydrophobicity of R-group of [R4N]Cl alters the [denaturant]-dependent conformational stability, refolding-unfolding kinetics, and CO-association kinetics of Cyt c. Furthermore, the MD simulations depicted that the addition of 1.0 M of [R4N]Cl increased the conformational fluctuations in Cyt c leading to decreased structural stability in the order [Me4N]Cl < [Et4N]Cl < [Pr4N]Cl < [Bu4N]Cl consistent with the experimental results.

Sex-dependent differences in macaque brain mitochondria.

Mitochondrial bioenergetics in females and males is different. However, whether mitochondria from male and female brains display differences in enzymes of oxidative phosphorylation remains unknown. Therefore, we characterized mitochondrial complexes from the brains of male and female macaques (Macaca mulatta). Cerebral tissue from male macaques exhibits elevated content and activity of mitochondrial complex I (NADH:ubiquinone oxidoreductase) and higher activity of complex II (succinate dehydrogenase) compared to females. No significant differences between sexes were found in the content of α-ketoglutarate dehydrogenase or in the activities of cytochrome c oxidase and F1Fo ATPase. Our results underscore the need for further investigations to elucidate sex-related mitochondrial differences in humans.

Recombinant Biogenesis and Analysis of Cytochrome c Species.

Recombinant expression and biogenesis of cytochrome c species is a simple and efficient method for the production of holocytochrome c species, thus presenting an avenue for the study of cytochrome c or the cytochrome c biogenesis pathways responsible for heme attachment. Here, we describe a method for recombinant E. coli production of holocytochrome c utilizing the System I (CcmABCDEFGH) bacterial cytochrome c biogenesis pathway, followed by analysis of cytochrome c species by cell lysis and heme stain.

Integrating wing morphometrics and mitochondrial DNA analysis to assess the filaria vector Mansonia uniformis (Diptera: Culicidae) populations in Thailand.

Mansonia uniformis (Diptera: Culicidae) is recognized as a vector of Brugia malayi and has been reported to transmit Wuchereria bancrofti, both causing lymphatic filariasis in humans. This study employed geometric morphometrics (GM) to investigate wing shape variation and analyzed genetic diversity through cytochrome c oxidase subunit 1 (COI) gene analyses in Ma. uniformis populations across Thailand. Wing GM analyses indicated significant differences in wing shape based on Mahalanobis distances among nearly all population pairs (p < 0.05), with no significant correlation between wing shape and geographic distance (r = 0.210, p > 0.05). Genetic analyses identified 63 haplotypes and 49 polymorphic sites, with the overall population exhibiting a nucleotide diversity of 0.006 (± 0.001) and a haplotype diversity of 0.912 (± 0.017). Deviations from neutrality, as indicated by Tajima's D and Fu's FS tests for the overall Ma. uniformis populations in Thailand, were statistically significant and negative, suggesting population expansion (both p < 0.05). Analysis of molecular variance revealed no significant genetic structure when all populations were categorized based on collection sites and geographic regions. However, significant differences in FST values were observed between some populations. These findings enhance our understanding of the geographical and genetic factors influencing Ma. uniformis populations, which are crucial for developing effective control strategies in Thailand.

Galactose-1-phosphate inhibits cytochrome c oxidase and causes mitochondrial dysfunction in classic galactosemia.

Classic galactosemia is an inborn error of metabolism caused by mutations in the GALT gene resulting in the diminished activity of the galactose-1-phosphate uridyltransferase enzyme. This reduced GALT activity leads to the buildup of the toxic intermediate galactose-1-phosphate and a decrease in ATP levels upon exposure to galactose. In this work, we focused our attention on mitochondrial oxidative phosphorylation in the context of this metabolic disorder. We observed that galactose-1-phosphate accumulation reduced respiratory rates in vivo and changed mitochondrial function and morphology in yeast models of galactosemia. These alterations are harmful to yeast cells since the mitochondrial retrograde response is activated as part of the cellular adaptation to galactose toxicity. In addition, we found that galactose-1-phosphate directly impairs cytochrome c oxidase activity of mitochondrial preparations derived from yeast, rat liver, and human cell lines. These results highlight the evolutionary conservation of this biochemical effect. Finally, we discovered that two compounds - oleic acid and dihydrolipoic acid - that can improve the growth of cell models of mitochondrial diseases, were also able to improve galactose tolerance in this model of galactosemia. These results reveal a new molecular mechanism relevant to the pathophysiology of classic galactosemia - galactose-1-phosphate-dependent mitochondrial dysfunction - and suggest that therapies designed to treat mitochondrial diseases may be repurposed to treat galactosemia.

A flexible linker of 8-amino acids between the membrane binding segment and the FMN domain of cytochrome P450 reductase is necessary for optimal activity.

The diflavin NADPH-cytochrome P450 reductase (CYPOR) plays a critical role in human cytochrome P450 (CYP) activity by sequentially delivering two electrons from NADPH to CYP enzymes during catalysis. Although electron transfer to forty-eight human CYP enzymes by the FMN hydroquinone of CYPOR is well-known, the role of the linker between the NH2-terminus membrane-binding domain (MBD) and FMN domain in supporting the activity of P450 enzymes remains poorly understood. Here we demonstrate that a linker with at least eight residues is required to form a functional CYPOR-CYP2B4 complex. The linker has been shortened in two amino-acid increments from Phe44 to Ile57 using site directed mutagenesis. The ability of the deletion mutants to support cytochrome P450 2B4 (CYP2B4) catalysis and reduce ferric CYP2B4 was determined using an in vitro assay and stopped-flow spectrophotometry. Steady-state enzyme kinetics showed that shortening the linker by 8-14 amino acids inhibited (63-99%) the ability of CYPOR to support CYP2B4 activity and significantly increased the Km of CYPOR for CYP2B4. In addition, the reductase mutants decreased the rate of reduction of ferric CYP2B4 (46-95%) compared to wildtype when the linker was shortened by 8-14 residues. These results indicate that a linker with a minimum length of eight residues is necessary to enable the FMN domain of reductase to interact with CYP2B4 to form a catalytically competent complex. Our study provides evidence that the length of the MBD-FMN domain linker is a major determinant of the ability of CYPOR to support CYP catalysis and drug metabolism by P450 enzymes. PREAMBLE: This manuscript is dedicated in memory of Dr. James R. Kincaid who was the doctoral advisor to Dr. Freeborn Rwere and a longtime collaborator and friend of Dr. Lucy Waskell. Dr. James R. Kincaid was a distinguished professor of chemistry specializing in resonance Raman (rR) studies of heme proteins. He inspired Dr. Rwere (a Zimbabwean native) and three other Zimbabweans (Dr. Remigio Usai, Dr. Daniel Kaluka and Ms. Munyaradzi E. Manyumwa) to use lasers to document subtle changes occurring at heme active site of globin proteins (myoglobin and hemoglobin) and cytochrome P450 enzymes. Dr. Rwere appreciate his contributions to the development of talented Black scientists from Africa.

[Molecular tracing of Biomphalaria straminea in China].

OBJECTIVE: To investigate the origin of Biomphalaria straminea in China, so as to provide insights into assessment of schistosomiasis mansoni transmission risk and B. straminea control. METHODS: Guanlan River, Dasha River, Shenzhen Reservoir, upper and lower reaches of Kuiyong River, and Xinzhen River in Shenzhen, China, were selected as sampling sites. Ten Biomphalaria samples were collected from each site, and genomic DNA was extracted from Biomphalaria samples. DNA samples were obtained from 15 B. straminea sampled from 5 sampling sites in Minas Gerais State, Pará State, Federal District, Pernambuco State, and Sao Paulo State in Brazil, South America. Cytochrome c oxidase I (COI) and mitochondrial 16S ribosomal RNA (16S rRNA) genes were sampled using the above DNA templates, and the amplified products were sequenced. The COI and 16S rRNA gene sequences were downloaded from GenBank, and the sampling sites were acquired. All COI and 16S rRNA gene sequences were aligned and evolutionary trees of B. straminea were created based on COI and 16S rRNA gene sequences to identify the genetic similarity and evolutionary relationship between B. straminea samples from China and South America. RESULTS: A total of 60 COI gene sequences with a length of 529 bp and 3 haplotypes were obtained from B. straminea sampled from China. There were 165 COI gene sequences of B. straminea retrieved from GenBank, and following alignment with the above 60 gene sequences, a total of 33 haplotypes were obtained. Phylogenetic analysis showed that the three haplotypes of B. straminea from China were clustered into one clade, among which the haplotype China11 and three B. straminea samples from Brazil retrieved from GenBank belonged to the same haplotype. Geographical evolution analysis showed that the B. straminea samples from three sampling sites along eastern coasts of Brazil had the same haplotype with China11, and B. straminea samples from other two sampling sites were closely, genetically related to China11. A total of 60 16S rDNA gene sequences with approximately 322 bp in length were amplified from B. straminea in China, with 2 haplotypes identified. A total of 70 16S rDNA gene sequences of B. straminea were captured from GenBank. Phylogenetic analysis showed that Biomphalaria snails collected from China were clustered into a clade, and the haplotype China64 and the haplotype 229BS from Brazil shared the same haplotype. The 49 16S rDNA gene sequences of B. straminea from 25 sampling sites in southern Brazil, which were captured from GenBank, were included in the present analysis, and the B. straminea from 3 sampling sites shared the same haplotype with China64 in China. Geographical evolution analysis based on COI and 16S rRNA gene sequences showed that B. straminea sampled from eastern coastal areas of Brazil shared the same haplotypes in two gene fragment sequences with Biomphalaria snails collected from China. CONCLUSIONS: The Biomphalaria snails in China are characterized as B. straminea, which have a low genetic diversity. The Biomphalaria snails in China have a high genetic similarity with B. straminea sampled from eastern coastal areas of Brazil, which may have originated from the eastern coastal areas of Brazil.