A frog-derived antimicrobial peptide as a potential anti-biofilm agent in combating Staphylococcus aureus skin infection.

Staphylococcus aureus (S. aureus), one of the most prevalent bacteria found in atopic dermatitis lesions, can induce ongoing infections and inflammation by downregulating the expression of host defence peptides in the skin. In addition, the emergence of the 'superbug' Methicillin-resistant S. aureus (MRSA) has made the treatment of these infections more challenging. Antimicrobial peptides (AMPs), due to their potent antimicrobial activity, limited evidence of resistance development, and potential immunomodulatory effects, have gained increasing attention as potential therapeutic agents for atopic dermatitis. In this study, we report a novel AMP, brevinin-1E-OG9, isolated from the skin secretions of Odorrana grahami, which shows potent antibacterial activity, especially against S. aureus. Based on the characteristics of the 'Rana Box', we designed a set of brevinin-1E-OG9 analogues to explore its structure-activity relationship. Brevinin-1E-OG9c-De-NH2 exhibited the most potent antimicrobial efficacy in both in vitro and ex vivo studies and attenuated inflammatory responses induced by lipoteichoic acid and heat-killed microbes. As a result, brevinin-1E-OG9c-De-NH2 might represent a promising candidate for the treatment of S. aureus skin infections.

A Designed Analog of an Antimicrobial Peptide, Crabrolin, Exhibits Enhanced Anti-Proliferative and In Vivo Antimicrobial Activity.

Antimicrobial peptides have gradually attracted interest as promising alternatives to conventional agents to control the worldwide health threats posed by antibiotic resistance and cancer. Crabrolin is a tridecapeptide extracted from the venom of the European hornet (Vespa crabro). Its antibacterial and anticancer potentials have been underrated compared to other peptides discovered from natural resources. Herein, a series of analogs were designed based on the template sequence of crabrolin to study its structure-activity relationship and enhance the drug's potential by changing the number, type, and distribution of charged residues. The cationicity-enhanced derivatives were shown to have improved antibacterial and anticancer activities with a lower toxicity. Notably, the double-arginine-modified product, crabrolin-TR, possessed a potent capacity against Pseudomonas aeruginosa (minimum inhibitory concentration (MIC) = 4 µM), which was around thirty times stronger than the parent peptide (MIC = 128 µM). Furthermore, crabrolin-TR showed an in vivo treatment efficacy in a Klebsiella-pneumoniae-infected waxworm model and was non-toxic under its maximum MBC value (MIC = 8 µM), indicating its therapeutic potency and better selectivity. Overall, we rationally designed functional peptides by progressively increasing the number and distribution of charged residues, demonstrating new insights for developing therapeutic molecules from natural resources with enhanced properties, and proposed crabrolin-TR as an appealing antibacterial and anticancer agent candidate for development.

A Novel Antimicrobial Peptide, Dermaseptin-SS1, with Anti-Proliferative Activity, Isolated from the Skin Secretion of Phyllomedusa tarsius.

The emergence of multidrug-resistant bacteria has severely increased the burden on the global health system, and such pathogenic infections are considered a great threat to human well-being. Antimicrobial peptides, due to their potent antimicrobial activity and low possibility of inducing resistance, are increasingly attracting great interest. Herein, a novel dermaseptin peptide, named Dermaseptin-SS1 (SS1), was identified from a skin-secretion-derived cDNA library of the South/Central American tarsier leaf frog, Phyllomedusa tarsius, using a 'shotgun' cloning strategy. The chemically synthesized peptide SS1 was found to be broadly effective against Gram-negative bacteria with low haemolytic activity in vitro. A designed synthetic analogue of SS1, named peptide 14V5K, showed lower salt sensitivity and more rapid bacteria killing compared to SS1. Both peptides employed a membrane-targeting mechanism to kill Escherichia coli. The antiproliferative activity of SS1 and its analogues against lung cancer cell lines was found to be significant.

Strategic job market-guided development of pharmacy bachelor's curriculum and its importance in maintaining the profession viability in the Middle Eastern countries: Colleges of pharmacy in the UAE as a model.

The Middle East has high youth population; however, it is challenged by uncertain economic situation. Higher education plays a crucial role in the development of nations by equipping generations with the knowledge and skill through cumulative curriculum development. Like other professions, pharmacy is a dynamic field of study where continuous improvements are required to keep the viability of the profession and endow future generations with up to date skills. This article describes a strategy for pharmacy curriculum development considering four layers. The strategy starts from the understanding of the current situation in a university, looking into national, international accreditations and job market. The strategy covers development from program to subject's level. The strategy is applied to pharmacy programs in the UAE. Upon analysis, several recommendations were obtained for curriculum improvements. At individual university level, there is a need to work on clinical oriented topics in the curriculum to fit with international accreditation and country's vision. Details on this can be taken form deeper analysis of job market and stakeholders in the UAE. On the national level, unifications of total credit hours for the degree across universities needs to be envisaged with limits on contact experiential hours. The strategy has the potential of extrapolating to other Middle Eastern countries.

miR-19a/19b improves the therapeutic potential of mesenchymal stem cells in a mouse model of myocardial infarction.

Myocardial infarction (MI) is the cardiac emergency that may leads to myocardial necrosis. Mesenchymal stem cells (MSCs) could be used to induce myocardial differentiation. However, the efficiency remains low. The aim of this study is to explore whether miR-19a/19b could enhance the therapeutic potential of mesenchymal stem cells in MI. Myocardial infarction mouse model was established using coronary artery ligation. Cardiac functional recovery was detected by Masson's trichrome staining. Under hypoxic condition, miR-19a/19b expression levels decreased in bone marrow-derived MSCs (BM-MSCs). MiR-19a/19b suppressed the proliferation of MSCs under hypoxic condition. After cell engraftment, miR-19a/19b promoted survival of MSCs. Mechanically, miR-19a/19b inhibited inflammatory cells infiltration into myocardium cells. Moreover, MSCs-miR-19a/19b improves cardiac functional recovery in diabetic MI mice models. All the results indicated that miR-19a/19b improves the therapeutic potential of mesenchymal stem cells in a mouse model of myocardial infarction.

Sparse-aperture photonics-integrated interferometer (SPIN) imaging system: structural design and imaging quality analysis.

The burgeoning field of astrophotonics, the interface between astronomy and photonics, is redefining astronomical instrumentation to replace traditional bulk optical systems with integrated optics. This drives the development of a new promising photonics-integrated interferometric imaging technique, called the segmented planar imaging detector for electro-optical reconnaissance (SPIDER). Compared to conventional imaging systems, SPIDER can reduce the size, weight, and power (SWaP) by one to two orders of magnitude for an equivalent imaging resolution in virtue of photonics-integrated technology. However, SPIDER has a dense lens distribution and tens of separated narrow wavebands demultiplexed by array waveguide gratings. In this paper, we developed a new simplified sparse-aperture photonics-integrated interferometer (SPIN) imaging system. The SPIN imaging system was no more a Michelson configuration interferometer as SPIDER and was designed as a Fizeau configuration interferometer imaging system. This transfer of configuration type affords a more concise structure; the SPIN was designed with much less apertures and fewer wavebands than those of SPIDER. Further, the SPIN yields enhanced modulation transfer function and imaging quality with equivalent aperture diameter, compared with SPIDER. The main barrier of this transfer is the elimination of coupling restriction at the tip of a waveguide, namely the apodization effect. This effect, which is caused by the coupling effect between Fourier lens and waveguide, hinders SPIN imaging systems from getting finer resolution. However, a microscope could be used to eliminate this effect. Moreover, a waveguide array is used to receive these finer details and enlarges the field of view in SPIN. The coupling efficiency of the waveguides and crosstalk errors between waveguides of array were analyzed, which are important for proper parameters setting in SPIN imaging system. Based on these analyses, the imaging principle was derived and a hyper-Laplacian-based imaging reconstruction algorithm was developed. A simulation of the SPIN imaging system with seven apertures and one imaging waveband demonstrated the high imaging quality.

In vitro activities of a novel antimicrobial peptide isolated from phyllomedusa tomopterna.

Because of the abuse of antibiotics, clinical strains began to become more drug-resistant. Their evolution has long surpassed the speed of us looking for a new generation of antibacterial drugs. Therefore, it is urgent to discover a new antimicrobial substance to alleviate the pressure on conventional antibiotics. Antimicrobial peptides (AMP) are known for their significant activity towards a broad spectrum of bacteria, protozoa, yeasts, filamentous fungi. Here, we report a novel AMP named Dermaseptin-TO. Results demonstrate that Dermaseptin-TO can quickly exhibit antimicrobial activity to bacteria and yeast in a dose-related way. The highest minimum inhibit concentration (MIC) was observed in the E.faecalis group (128 µM). Also, haemolytic outcomes showed no more than 10.65% of red blood cells were affected when in the same concentrations or below. Besides, Dermaseptin-TO also showed anticancer activity at a higher concentration. From the above, evidence proved that Phyllomedusine frog skin secretion is still a rich source that contains novel AMP and Dermaseptin-TO is competent to become an antimicrobial agent, its anticancer activity may broaden the way in basic cancer research. Also, following the same templates in molecular cloning may acquire new AMP classes with potent antimicrobial effects that could widen drug design in new anti-infective drugs.

Evaluation of antimicrobial and anticancer activities of three peptides identified from the skin secretion of Hylarana latouchii.

The skins of frogs of the family Ranidae are particularly rich sources of biologically active peptides, among which antimicrobial peptides (AMPs) constitute the major portion. Some of these have attracted the interest of researchers because they possess both antimicrobial and anticancer activities. In this study, with 'shotgun' cloning and MS/MS fragmentation, three AMPs, homologues of family brevinin-1 (brevinin-1HL), and temporin (temporin-HLa and temporin-HLb), were discovered from the skin secretion of the broad-folded frog, Hylarana latouchii. They exhibited various degrees of antimicrobial and antibiofilm activities against test microorganisms and hemolysis on horse erythrocytes. It was found that they could induce bacteria death through disrupting cell membranes and binding to bacterial DNA. In addition, they also showed different potencies towards human cancer cell lines. The secondary structure and physicochemical properties of each peptide were investigated to preliminarily reveal their structure-activity relationships. Circular dichroism spectrometry showed that they all adopted a canonical α-helical conformation in membrane-mimetic solvents. Notably, the prepropeptide of brevinin-1HL from H. latouchii was highly identical to that of brevinin-1GHd from Hylarana guentheri, indicating a close relationship between these two species. Accordingly, this study provides candidates for the design of novel anti-infective and antineoplastic agents to fight multidrug-resistant bacteria and malignant tumors and also offers additional clues for the taxonomy of ranid frogs.

Aggregation and Its Influence on the Bioactivities of a Novel Antimicrobial Peptide, Temporin-PF, and Its Analogues.

Temporin is an antimicrobial peptide (AMP) family discovered in the skin secretion of ranid frog that has become a promising alternative for conventional antibiotic therapy. Herein, a novel temporin peptide, Temporin-PF (TPF), was successfully identified from Pelophylax fukienensis. It exhibited potent activity against Gram-positive bacteria, but no effect on Gram-negative bacteria. Additionally, TPF exhibited aggregation effects in different solutions. Three analogs were further designed to study the relationship between the aggregation patterns and bioactivities, and the MD simulation was performed for revealing the pattern of the peptide assembly. As the results showed, all peptides were able to aggregate in the standard culture media and salt solutions, especially CaCl2 and MgCl2 buffers, where the aggregation was affected by the concentration of the salts. MD simulation reported that all peptides were able to form oligomers. The parent peptide assembly depended on the hydrophobic interaction via the residues in the middle domain of the sequence. However, the substitution of Trp/D-Trp resulted in an enhanced inter-peptide interaction in the zipper-like domain and eliminated overall biological activities. Our study suggested that introducing aromaticity at the zipper-like domain for temporin may not improve the bioactivities, which might be related to the formation of aggregates via the inter-peptide contacts at the zipper-like motif domain, and it could reduce the binding affinity to the lipid membrane of microorganisms.

Novel peptide dermaseptin-PS1 exhibits anticancer activity via induction of intrinsic apoptosis signalling.

Antimicrobial peptides (AMP) secreted by the granular glands of frog skin have been widely reported to exhibit strong bacteriostatic and bactericidal activities. Many of them have been documented with potent antiproliferative effects on multiple cancer cells, many studies also suggested that AMPs exert their functions via disrupting cell membranes. However, whether and how other cell death induction mechanism is involved in mammalian cancer cells has rarely been investigated. In this study, a novel AMP named Dermaseptin-PS1 was isolated and identified from Phyllomedusa sauvagei, it showed strong antimicrobial activities against three types of microorganisms. In vitro antiproliferative studies on human glioblastoma U-251 MG cells indicated that Dermaseptin-PS1 disrupted cell membranes at the concentrations of 10-5  M and above, while the cell membrane integrity was not affected when concentrations were decreased to 10-6  M or lower. Further examinations revealed that, at the relatively low concentration (10-6  M), Dermaseptin-PS1 induced apoptosis through mitochondrial-related signal pathway in U-251 MG cells. Thus, for the first time, we report a novel frog skin derived AMP with anticancer property by distinct mechanisms, which largely depends on its concentration. Together, our study provides new insights into the mechanism-illustrated drug design and the optimisation of dose control for cancer treatment in clinic.

Phylloseptin-PBa1, -PBa2, -PBa3: Three novel antimicrobial peptides from the skin secretion of Burmeister's leaf frog (Phyllomedusa burmeisteri).

Skin secretions are known as a highly-complex mixture of abundant and diverse bioactive molecules and its study has attracted increasing attention over recent years. Phylloseptin is a unique family of antimicrobial peptides which have been only isolated from frogs of the Phyllomedusinae subfamily. Here, three novel peptide precursors were successfully cloned from a cDNA library, which was constructed from the skin secretion of Phyllomedusa burmeisteri, as pair of primers (one nested universal primer and a designed degenerate sense primer) were employed for "shotgun" cloning. The encoded mature peptides were validated by MS/MS sequencing, and subsequently termed as Phylloseptin-PBa1, -PBa2 and -PBa3. Phylloseptin-PBa1 and -PBa2 were demonstrated to possess potent antimicrobial activities against Gram-positive bacteria and yeast, as well as broad-spectrum anticancer activities, while they possess varying haemolytic activity at the effective concentration. In contrast, Phylloseptin-PBa3 was found to exhibit a strong haemolytic activity even though it was only found to possess a weak antimicrobial activity and inconspicuous anticancer activity.

Skin secretion transcriptome remains in chromatographic fractions suitable for molecular cloning.

Traditional sources of mRNA for molecular cloning on amphibian skin secretion studies have been the frog's skin and skin secretions. Here, we demonstrate that mRNA isolated from chromatographic fractions of skin secretions is amenable for molecular cloning assays. We identified precursor sequences of the Arg0, Trp5, Leu8-bradykinin and six antimicrobial peptides of Pelophylax esculentus (Ranidae). These results show that both transcriptomic and peptidomic analyses can be performed with a single sample reducing in half the amount of starting skin secretion required. This is a significant advantage when working with endangered or very rare amphibian species, where minimal samples are available.

Cloning of a novel trypsin inhibitor from the Traditional Chinese medicine decoction pieces, Radix Trichosanthis.

Most herbs of traditional Chinese medicine (TCM) are used as air-dried decoction pieces that are manufactured and kept at ambient temperature for long periods. Given the ability of some desiccation-tolerant plants to conserve RNA, it could be worthwhile to isolate mRNA from TCM decoction pieces as part of a transcriptomic strategy to identify new substances with potential pharmaceutical application. Here, we report the molecular cloning of a novel trypsin inhibitor (as the probable alleleic variants TKTI-2 and TKTI-3) from the decoction piece of Radix Trichosanthis, representing the dried root of Trichosanthes kirilowii. From this material, the total RNA was extracted and a cDNA library was constructed from the isolated mRNA from which the cDNAs of two precursors were successfully cloned and sequenced. TKTI-3 showed an amino-acid substitution in the otherwise highly-conserved P1-P1' reaction site of the mature peptide, which we confirmed to not be an artefact. Subsequent analysis using LC-MS/MS detected the presence of specific tryptic peptides expected from TKTI-3, confirming the presence and expression of this locus in Radix Trichosanthis. More generally, this study indicates that mRNA can persist in decoction pieces and so could present a viable option for the molecular cloning from other TCMs.

Evaluating the Bioactivity of a Novel Antimicrobial and Anticancer Peptide, Dermaseptin-PS4(Der-PS4), from the Skin Secretion of Phyllomedusa sauvagii.

Dermaseptins belonging to a large family of cationic membrane-disruption antimicrobial peptides display extensive antibacterial and antiproliferative activities depending on a coil-to-helix transition and the specific structural parameters. Herein, a novel dermaseptin peptide named Der-PS4 was discovered from the skin secretion of the waxy monkey tree frog, Phyllomedusa sauvagii. The complementary DNA (cDNA)-encoding precursor was obtained relying on "shotgun" cloning, and afterwards, a mature peptide amino acid sequence was identified by reverse-phase high performance liquid chromatography (RP-HPLC) and MS/MS. Specimens were chemically synthesized and applied for further functional studies. Structural analysis demonstrated a higher α-helical content in the membrane-mimetic environment compared with that in the ammonium acetate/water circumstance. Der-PS4 displayed a broad spectrum of antimicrobial activities against tested pathogenic microorganisms, however, exhibiting slight membrane-damaging effectiveness towards horse red blood cells. Coincident with the inhibitory activities on pathogens, Der-PS4 also showed considerable biofilm eradicating impact. Also, Der-PS4 penetrated cell membrane in a relative short period under each minimum bactericidal concentration. In addition, Der-PS4 possessed antiproliferative capacity against five cancer cell lines, while presenting slight suppressing effect on human microvascular endothelial, HMEC-1. These findings provide a promising insight for the discovery and development of novel drugs from a natural source.

A novel peptide Phylloseptin-PBu from Phyllomedusa burmeisteri possesses insulinotropic activity via potassium channel and GLP-1 receptor signalling.

Insulin, as one of the most important hormones regulating energy metabolism, plays an essential role in maintaining glucose and lipid homeostasis in vivo. Failure or insufficiency of insulin secretion from pancreatic beta-cells increases glucose and free fatty acid level in circulation and subsequently contributes to the emergence of hyperglycaemia and dyslipidaemia. Therefore, stimulating the insulin release benefits the treatment of type 2 diabetes and obesity significantly. Frog skin peptides have been extensively studied for their biological functions, among which, Phylloseptin peptides discovered in Phyllomedusinae frogs have been found to exert antimicrobial, antiproliferative and insulinotropic activities, while the mechanism associated with Phylloseptin-induced insulin secretion remains elusive. In this study, we reported a novel peptide named Phylloseptin-PBu, isolated and identified from Phyllomedusa burmeisteri, exhibited dose-dependent insulinotropic property in rat pancreatic beta BRIN-BD11 cells without altering cell membrane integrity. Further mechanism investigations revealed that Phylloseptin-PBu-induced insulin output is predominantly modulated by KATP -[K+ ] channel depolarization triggered extracellular calcium influx and GLP-1 receptor initiated PKA signalling activation. Overall, our study highlighted that this novel Phylloseptin-PBu peptide has clear potential to be developed as a potent antidiabetic agent with established function-traced mechanism and low risk of cytotoxicity.

Identification of novel Amurin-2 variants from the skin secretion of Rana amurensis, and the design of cationicity-enhanced analogues.

Rana amurensis is important in Chinese medicine as its skin secretions contain abundant bioactive peptides. Here, we have identified the antimicrobial peptide Amurin-2 and three highly-conserved variants, Amurin-2a, Amurin-2b and Amurin-2c through a combination of molecular cloning and MS/MS fragmentation sequencing. Synthetic replicates of these peptides demonstrate potent antimicrobial activity against S. aureus, whilst some have activity against C.albicans and even resistant bacterial MRSA. Furthermore, two Lys-analogues (K4-Amurin-2 and K11-Amurin-2) were designed to improve the bioactive function and the antimicrobial activity of K4-Amurin-2 against E.coli was enhanced distinctly. In addition, the two modified peptides also showed more potent activity against S. aureus, C. albicans and MRSA strains. Meanwhile, these peptides showed inhibitory effect on the cell viability of several cancer cells. As a result, these structural and functional studies of Amurin-2 variants and analogues could provide insights for future antimicrobial peptide design.

Identification and target-modifications of temporin-PE: A novel antimicrobial peptide in the defensive skin secretions of the edible frog, Pelophylax kl. esculentus.

A potent natural antimicrobial peptide named temporin-PE was identified and encoded from the skin secretions of Pelophylax kl. esculentus via "shotgun" cloning and LC-MS/MS fragmentation analysis. Target-modifications were carried out to further enhance the antimicrobial and anti-proliferative bioactivities, whilst decreasing the hemolytic effect. A range of bioassays demonstrated that replacing a proline with a tyrosine residue resulted in a loss of the bioactivity against Gram-negative bacteria, but dramatically improved the hemolytic and anti-proliferative activity, indicating the FLP- motif influences the hemolytic activity of temporins. Moreover, the coupling of TAT to the peptide dramatically improved its antimicrobial activity, indicating coupling TAT to these peptides could be considered as a potential tool to improve their antimicrobial activity. Overall, we have shown that targeted modifications of this natural antimicrobial peptide can adjust its bioactivities to help its development as an antibiotic or anti-proliferative agent.

Synthesis and luminescence properties of Ca3 (BO3 )2 :Eu3+ via two-step method.

Novel Ca2 B2 O5 ·H2 O:Eu3+ nanotubes, constructed with nanobelts, were prepared using a hydrothermal method. The Ca3 (BO3 )2 :Eu3+ nanobelts with a thickness of about 100 nm were made for the first time using a two-step hydrothermal process with Ca2 B2 O5 ·H2 O:Eu3+ as the precursor. The samples were characterized by energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infra-red spectroscopy, thermogravimetry differential thermal analysis and scanning electron microscopy. The relationship between Ca3 (BO3 )2 :Eu3+ and Ca2 B2 O5 ·H2 O:Eu3+ was also studied. Possible reaction and growth mechanisms for Ca2 B2 O5 ·H2 O:Eu3+ and Ca3 (BO3 )2 :Eu3+ were proposed. Ca3 (BO3 )2 :Eu3+ preserved the basic microstructure unit of Ca2 B2 O5 ·H2 O:Eu3+ . Both Ca2 B2 O5 ·H2 O:Eu3+ and Ca3 (BO3 )2 :Eu3+ exhibited red emissions centred at 614 nm, but the maximum excitation peaks for Ca2 B2 O5 ·H2 O:Eu3+ and Ca3 (BO3 )2 :Eu3+ differed. Ca3 (BO3 )2 :Eu3+ exhibited higher photoluminescence intensity but a lower R/O value than Ca2 B2 O5 ·H2 O:Eu3+ .

Synchronized and controlled release of metformin hydrochloride/glipizide from elementary osmotic delivery.

The combination of metformin hydrochloride (MTF) and glipizide (GLZ) is second-line medication for diabetes mellitus type 2 (DMT2). In the present study, elementary osmotic pump ( EOP) tablet is designed to deliver the combination of MTF and GLZ in a sustained and synchronized manner. By analyzing different variables of the formulation, sodium hydrogen carbonate is introduced as pH modifier to improve the release of GLZ, while ethyl cellulose acts as release retardant to reduce the burst release phase of MTF. A two-factor, three-level face-centered central composite design (FCCD) is applied to investigate the impact of different factors on drug release profile. Compared with conventional tablets, the EOP tablet demonstrates a controlled release behavior with relative bioavailability of 99.2% for MTF and 99.3% for GLZ. Data also shows EOP tablet is able to release MTF and GLZ in a synchronized and sustained manner both in vitro and in vivo.

Ranatensin-HL: A Bombesin-Related Tridecapeptide from the Skin Secretion of the Broad-Folded Frog, Hylarana latouchii.

Bombesin-related peptides are a family of peptides whose prototype was discovered in amphibian skin and which exhibit a wide range of biological activities. Since the initial isolation of bombesin from Bombina bombina skin, diverse forms of bombesin-related peptides have been found in the skins across Anura. In this study, a novel bombesin-related peptide of the ranatensin subfamily, named ranatensin-HL, was structurally-characterised from the skin secretion of the broad-folded frog, Hylarana latouchii, through combination of molecular cloning and mass spectrometric methodologies. It is composed of 13 amino acid residues, pGlu-RAGNQWAIGHFM-NH2, and resembles an N-terminally extended form of Xenopus neuromedin B. Ranatensin-HL and its C-terminal decapeptide (ranatensin-HL-10) were chemically synthesised and subjected to in vitro smooth muscle assays in which they were found to display moderate stimulatory effects on rat urinary bladder and uterus smooth muscles with EC50 values in the range of 1-10 nM. The prepro-ranatensin-HL was highly homological to a bombesin-like peptide from Rana catesbeiana at both nucleotide and amino acid levels, which might provide a clue for the taxonomic classification of ranid frogs in the future.