Molecular diversity of populations of the Merodon ruficornis group (Diptera, Syrphidae) on the Balkan Peninsula

Genetic diversity of 11 populations of the Merodon ruficornis group (Diptera, Syrphidae) on the Balkan Peninsula was quantified using allozyme electrophoresis and nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I. A total of 10 haplotypes of mtDNA were found in 22 analysed individuals. One haplotype was shared between M. loewi (from Pindos and Duba?nica Mts) and M. armipes, one confined to M. auripes (haplotype III) and M. armipes (VII) and three to M. trebevicensis (VIII, IX and X), M. ruficornis (I, II and IV) and M. loewi (V, VI and VII). Analysis of the population genetic structure parameters showed great differences among analysed species. Different levels of genetic variability suggested that a variety of biological, environmental and/or historical factors had influenced these hoverfly populations. The unweighted pair group method with arithmetic average dendrogram constructed using allozyme data suggested that M. loewi was the most divergent species in comparison with M. armipes, M. auripes, M. ruficornis and M. trebevicensis. Clear separation of the populations ((((M. armipes + M. auripes) + M. ruficornis) + M. trebevicensis) + M. loewi) was observed. The parsimony analysis of the M. ruficornis group using Merodon avidus as outgroup resulted in three equally parsimonious trees, and the strict consensus presented the following relationships ((((M. loewi + M. armipes) + (M. auripes)) + (M. trebevicensis)) + (M. ruficornis)))). The uncorrected interspecies pairwise sequence divergences ranged from 1.69% (between haplotype III of M. armipes and haplotype V of M. loewi) to 4.94% (between M. ruficornis and M. trebevicensis).     

The neural activities of the greater superficial petrosal nerve of the rat in response to chemical stimulation of the palate

A comparison of the integrated responses of the rat's greatersuperficial petrosal (GSP) and chorda tympani (CT) nerves toa number of taste stimuli was studied. The GSP nerve of therat was very responsive to the chemical stimulation of the oralcavity. Among the selected stimuli related to the four basictaste qualities, 0.5 M sucrose produced the greatest neuralresponse in the GSP nerve, whereas, 0.1 M NaCl produced thegreatest in the CT nerve. The GSP nerve integrated responseto 0.5 M sucrose solution was approximately three times as greatin magnitude as that to a 0.1 M NaCl solution. The neural responsemagnitude of the GSP and CT nerves were as follows: GSP nerve;0.5 M sucrose >0.02 M Na-saccharin >0.05 M citric acid>0.1 M NaCl > 0.01 M quinine-HCl. CT nerve; 0.1 M NaCl> 0.05 M citric acid > 0.02 M Na-saccharin > 0.01 Mquinine-HCl >0.5 M sucrose. The response magnitudes of theGSP nerve to 0.3 M chloride salt solutions were: LiCl > CaCl₂> NaCl > NH₄Cl > KCl, whereas the response magnitudesof the CT nerve to the above salts were: LiCl > NaCl >NH₄Cl > CaCl₂ > KCl. All 0.5 M solutions of the selectedsugars (sucrose, rhamnose, galactose, lactose, fructose, -methyl-D-glucoside,xylose, mannose, arabinose, maltose, sorbose and glucose) evokedneural responses in both GSP and CT nerves. The order of theresponse magnitudes of the GSP nerve to the selected sugarswas similar to that of the CT nerve but the absolute magnitudesof the GSP nerve were greater.     

Molecular analyses of the IGS & ITS regions of rDNA of the psychrophilic yeasts in the genus Mrakia

Species of the genus Mrakia are currently classified as synonyms based on molecular sequence analyses of the large sub-unit ribosomal DNA (LrDNA). Physiological and protein electrophoretic studies, however, reveal possible species differences. To clarify this discrepancy, we undertook molecular sequence analyses of the internal transcribed spacer (ITS) and intergenic spacer (IGS) regions of rDNA from the four psychrophilic Mrakia species and the psychrophilic yeast, Cryptococcus curiosus. Identical ITS sequences were found between C. curiosus, M. nivalis and M. frigida. Although, M. stokesii and M. gelida displayed identical ITS and IGS sequences, their sequences differed from the other three species by 2.3% and 38%, respectively. The results suggest that M. stokesii is a synonym of M. gelida, whereas M. nivalis is a synonym of M. frigida. Sequence differences (1.9%) observed in the IGS region indicates that C. curiosus is a distinct strain of M. frigida.     

Revision of the subgenus Udamochiras of Melaloncha bee-killing flies (Diptera: Phoridae: Metopininae)

The genus Melaloncha Brues is defined and groundplan character states established based on outgroup comparison with Phalacrotophora Enderlein and Melittophora Brues. Major groupings within Melaloncha are recognized, and two subgenera are established: Udamochiras Enderlein (type species M. colossia (Enderlein)) and Melaloncha s.s. (type species M. pulchella Brues). Subgenus Udamochiras is revised and 42 species are recognized, including the following 33 new to science: M. anaticula , M. angustifrons , M. apicula , M. aprica , M. basella , M. biseta , M. brevicarina , M. carinata , M. compressicauda , M. exigua , M. falcata , M. flavilata , M. hamata , M. hansoni , M. horologia , M. individa , M. lobata , M. maculifrons , M. parkeri , M. paxilla , M. premordica , M. rhampha , M. rhypopoda , M. rostrata , M. sinuosa , M. spatula , M. spicula , M. triangularis , M. trua , M. valeria , M. vargasi , M. villosa , M. woodi . Melaloncha simillima Borgmeier is removed from synonymy with M. piliapex Borgmeier and reinstated as a separate species; lectotypes are designated for both.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 1−42     

Kainate-Evoked Release of Adenosine from the Hippocampus of the Anaesthetised Rat: Possible Involvement of Free Radicals

Abstract: Using microdialysis in the hippocampus of anaesthetised rats, the concentration of extracellular adenosine was estimated to be 0.8 µ M . Kainic acid (0.1–25 m M ) in the perfusate evoked a concentration-dependent release of adenosine with an EC₅₀ of 940 µ M . Two 5-min pulses of 1 m M kainic acid in the perfusate increased the dialysate levels with an S2/S1 ratio of 0.52 ± 0.03. Kainate-evoked release of adenosine was reduced significantly by 10 µ M tetrodotoxin and by a κ-receptor agonist, U50,488H (100 µ M ). The S2/S1 ratio was reduced by 4.5 µ M 6-cyano-7-nitroquinoxaline-2,3-dione, a non-NMDA receptor antagonist, but not by the NMDA receptor blockers (+)-MK-801 (dizocilpine; 100 µ M ) or (±)-2-amino-5-phosphonopentanoic acid (1 m M ), indicating a non-NMDA receptor-mediated process. The S2/S1 ratio was also reduced significantly by 10 m M ascorbic acid, 10 m M glutathione (a scavenger of hydroperoxides), and 1 m M oxypurinol (a xanthine oxidase inhibitor), indicating the possible involvement of free radicals. Neither the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (100 µ M ) nor the A1 adenosine receptor agonist R (−)- N ⁶-(2-phenylisopropyl)adenosine (100 µ M ) affected release. Adenosine release evoked by kainic acid is therefore mediated by activation of non-NMDA receptors and may involve the propagation of action potentials and the production of free radicals.     

景宁木兰(Magnolia sinostellata)远缘杂交授粉过程障碍研究

以景宁木兰（Magnolia sinostellata）为亲本,分别与望春玉兰（M.biondii）、紫玉兰（M.liliiflora）、红运二乔（M.soulangeana ‘Red lucky’）、丹馨玉兰（M.soulangeana ‘Danxin’）进行种间远缘杂交,并以景宁木兰自交为对照,研究了景宁木兰自交和杂交亲和性。结果表明：（1）景宁木兰具有较高的花粉活力与柱头可授性,花粉管能正常进入杂交母本花柱,自交结实率为2%;（2）以景宁木兰为父本,紫玉兰柱头对其花粉具有较好的识别性,花粉萌发率和花粉管生长速度均高于以红运二乔和丹馨玉兰做母本的组合,花粉管生长较为正常,结实率为25%,而与红运玉兰杂交的结实率为4%,与丹馨玉兰杂交的结实率为0%;（3）以景宁木兰为母本,望春玉兰花粉在其柱头上的萌发比率高于其他4个组合,但花粉管生长过程中出现扭曲,景宁木兰花柱内出现胼胝质沉积,且最终并未获得种子。花粉管发育镜检结果表明：受精前障碍即花粉管进入花柱基部前生长异常是引起景宁木兰与丹馨玉兰、望春玉兰杂交不结实的主要原因;并进一步推测花粉管进入子房后的异常状态是导致景宁木兰自交,与红运二乔杂交结实率低的主要原因。     

Flavonoid chemistry of the endemic species of Myrceugenia (Myrtaceae) of the Juan Fernandez Islands and relatives in continental South America

Twenty-one flavonoids were isolated from the leaves of two endemic species ofMyrceugenia on the Juan Fernandez Islands,M. fernandeziana andM. schulzei, from two related species from Brazil,M. campestris andM. rufescens, and from five species from continental Chile,M. colchaguensis, M. exsucca, M. lanceolata, M. pinifolia, andM. rufa. A phenetic analysis was used to evaluate chemical similarities.Myrceugenia campestris andM. rufescens appear most closely related to each other based on flavonoid profiles, and they are also different from the other seven species. The two endemic species in the Juan Fernandez Islands,M. fernandeziana andM. schulzei, group with the continental Chilean species. The former is most closely related toM. lanceolata, and the latter clusters withM. exsucca, although somewhat distantly. The results suggest that the two Juan Fernandez endemics are derived from two introductions from the Chilean continent and not from immigrants from the eastern side of the Andes.     

Morphological variation of the five vole species of the genus Microtus (Mammalia,Rodentia, Arvicolinae) occurring in Greece

Morphometric data for the five vole species of the genus Microtus living in Greece are old, sparse, poor and insufficiently analysed. This work aims to give the first comprehensive morphometric analysis of body and skull inter‐ and intraspecific variation for M. (M.) guentheri, M. (M.) rossiaemeridionalis, M. (Terricola) subterraneus, M. (T.) felteni and M. (T.) thomasi, applying multivariate statistics to 28 linear morphometric variables. It was based on ample material (202 adult individuals) using samples from localities that adequately cover the entire distributional range of each species in Greece. The five species and the two subgenera (Microtus and Terricola) were morphometrically clearly distinguished and discriminating variables were revealed. However, morphometrics did not provide robust criteria to infer phylogenetic relations among species. Furthermore, three species, M. (M.) guentheri, M. (M.) rossiaemeridionalis and M. (T.) thomasi, exhibited considerable intraspecific size or shape variation, which was mostly random and not associated with geographical proximity. Comparisons with data in the literature, mainly concerning populations of these species from adjacent areas, indicate that the Greek M. (M.) guentheri, M. (M.) rossiaemeridionalis and M. (T.) thomasi tend to be smaller than their conspecifics, while M. (T.) subterraneus and M. (T.) felteni are about equal in size to their Balkan relatives.     

Review of the genus Macrosaldula Southwood et Leston, 1959 (Heteroptera,Saldidae) of the fauna of Russia and adjacent countries

The species of the genus Macrosaldula Southwood et Leston of the fauna of Russia and adjacent countries are reviewed. Fifteen species and one subspecies are distributed in the investigated territory (among these, eight species marked with an asterisk occur in Russia): M. clavalis Cobben, *M. jakovleffi Reut., M. kaszabi Hob., M. kerzhneri Cobben, M. koktshetavica Cobben, *M. koreana Kir., M. nivalis Lindb., *M. oblonga oblonga Stål, M. oblonga acetabularis Cobben, M. mongolica Kir., *M. rivularia J. Sahlb., *M. simulans Cobben, *M. scotica Curt., M. tadzhika Kir., *M. variabilis H.-S., and *M. violacea Cobben. An illustrated key to the species and dotted distribution maps are given.     

Morphology of the shoulder musculature of the American kestrel,Falco sparverius (Aves), with implications for gliding flight

Summary The shoulder morphology of the American kestrel,Falco sparverius, was dissected with an emphasis on the morphological requirements for gliding flight. Kestrels are being used as a model for the study of gliding flight in a non-specialized gliding bird. The kestrel forelimb is relatively generalized in its construction, and does not appear to have any remarkable specializations for gliding. However, several structures found in specialized gliders/soarers which may contribute to gliding were also found in kestrels; these include the presence of a scapular anchor and pectoral muscle fibers inserting onto the tendon of the biceps brachii muscle. This paper is the prelude to an experimental study on the gliding flight in this species and may serve as a basis for future functional or taxonomic comparisons.Abbreviations BB M. biceps brachii - Br M. brachialis - C coracoid - C12 12th cervical vertebra - CBA M. coracobrachialis cranialis - CBC M. coracobrachialis caudalis - DMA M. deltoideus major pars cranialis - DMa M. deltoideus major - DMC M. deltoideus major pars caudalis - DMi M. deltoideus minor - ECU M. extensor carpi ulnaris - EDC M. extensor digitorum communis - EMR M. extensor metacarpi radialis - ES M. expansor secundariorum - EU M. ectopicondylo-ulnaris - F furcula - FAH Facies articularis humeralis - FASc Facies articularis scapularis - FASt Facies articularis sternalis - ECU M. flexor carpi ulnaris - FP Fascia pectoralis - H humerus - HCB humerocarpal band - HS Os humeroscapularc and adjacent shoulder ligaments - K sternal keel - LDA M. latissimus dorsi pars cranialis - LDC M. latissimus dorsi pars caudalis - LMS Ligamentous portion of membrana sternocoracoclavicularis - MC Membrana cristoclavicularis - MS Membrana sternocoracoclavicularis - N Notarium - PB M. tensor propatagialis pars brevis - PC pectoral crest of humerus - PL M. tensor propatagialis pars longa - PP M. pronator profundus - PPB M. pectoralis propatagialis brevis - PPL M. pectoralis propatagialis longus - PS M. pronator superficialis - PT M. pectoralis pars thoracicus - RP M. rhomboideus profundus - RS M. rhomboideus superficialis - SA scapular anchor - SB M. subscapularis - SBe M. subscapularis pars externa - SBi M. subscapularis pars interna - SC M. supracoracoideus - Sc scapula - SHA M. scapulohumeralis cranialis - SHC M. scapulohumeralis caudalis - SP M. serratus profundus - SSA M. serratus superficialis pars cranialis - SSC M. serratus superficialis pars caudalis - SSM M. serratus superficialis pars metapatagialis - ST M. sternocoracoideus - St sternum - SU M. subcoracoideus - Su M. supinator - Sy synsacrum - T M. triceps - TH M. triceps humeralis - TS M. triceps scapularis     

Comparative analysis of the karyotype of the sculpin Myoxocephalus ochotensis (Pisces: Cottidae) from the Odyan Bay of the Sea of Okhotsk

The karyotype of the endemic Okhotsk Sea sculpin Myoxocephalus ochotensis Schmidt (Cottidae) from Odyan Bay was studied. The number and morphology of chromosomes were determined, 2n = 42 (2 metacentric, 20 subtelocentric, and 20 acrocentric chromosomes), NF = 44. Variability of chromosome number was not revealed; no difference between male and female karyotypes was found. The karyotype of the Okhotsk sculpin M. ochotensis was compared with karyotypes of the Far East Steller’s M. stelleri (Tilesius), snow M. brandti (Steindachner), and plain M. jaok (Cuvier) sculpins, and to the European shorthorn sculpin M. scorpius (Linnaeus) from White Sea. Their similarities and distinctions were shown.     

A Study of the Taxonomy of the Mycobacterium nonchromogenicum Complex and Report of Six Cases of Lung Infection Due to Mycobacterium nonchromogenicum

In numerical classification, four species of the Mycobacterium nonchromogenicum complex, Mycobacterium nonchromogenicum, M. terrae, M. novum, and M. triviale, formed one cluster. These four species appeared to be reduced to one species, Mycobacterium nonchromogenicum. Furthermore, relationships between the species were numerically analyzed by using the hypothetical median organism pattern. The results showed that the M. nonchromogenicum complex can be divided into two subgroups: M. nonchromogenicum and the other three. These two subgroups were differentiated from each other by scores based on two or more positive reactions in the following three characteristics: resistance to bleomycin (5 μg/ml); heat-stable acid phosphatase activity; nicotinamidase or pyrazinamidase activity or both activities. M. nonchromogenicum gave two or three positive reactions among these three, and M. terrae, M. novum, and M. triviale gave two or three negative reactions. Three cases of lung infection due to M. nonchromogenicum, as well as three other cases of probable lung infection due to M. nonchromogenicum, were observed in this study. Only one organism isolated from one doubtful case was M. terrae. Up to now, M. nonchromogenicum was considered a nonpathogen. It was shown, however, that this organism causes lung infection in humans.     

On the mechanism of salt tolerance

As glycerol was suggested as an osmotic agent in the salt tolerantDebaryomyces hansenii the concentrations of total, intracellular, and extracellular glycerol produced by this yeast was followed during growth in 4 mM, 0.68 M, and 2.7 M NaCl media. The total amount of glycerol was not directly proportional to biomass production but to the cultural salinity with maximum concentrations just prior to or at the beginning of the stationary phase. In all cultures the cells lost some glycerol to the media, at 2.7 M NaCl the extracellular glycerol even amounted maximally to 80% of the total. A distinct maximum of intracellular glycerol, related to dry weight or cell number, appeared during the log phase at all NaCl concentrations. As the intracellular calculated glycerol concentrations amounted to 0.2 M, 0.8 M, and 2.6 M in late log phase cells at 4 mM, 0.68 M, and 2.7 M NaCl, respectively, whereas the corresponding analysed values for the glycerol concentrations of the media were 0.7 mM, 2.5 mM, and 3.0 mM, glycerol contributes to the osmotic balance of the cells.During the course of growth all cultures showed a decreasing heat production related to cell substance produced, most pronounced at 2.7 M NaCl. At 2.7 M NaCl the total heat production amounted to-1690 kJ per mole glucose consumed in contrast to-1200 and-1130 kJ at 4 mM and 0.68 M NaCl, respectively. TheY _m -values were of an inverse order, being 129, 120, and 93 at 4 mM, 0.68 M, and 2.7 M NaCl, respectively.     

Inter- and intraspecific variation in the genitalia of the ‘Melitaea phoebe group’ (Lepidoptera, Nymphalidae)

The ecology and phylogeny of the Melitaeini butterflies have received considerable attention in the last few years. Several publications have been based on research using molecular methods. Genital morphometry has already been published on two sibling species but without any accompanying taxonomic revision of related species or their intraspecific taxonomy. In this study the morphology of genitalia was analysed by landmark-based geometric morphometrics in males and by traditional morphometrics in females. Based on these morphological characters, the whole M. phoebe group (subg. Cinclidia) was revised. According to our results M. telona Fruhstorfer, 1908 is conspecific with M. ‘phoebe’ ornata Christoph, 1893. Thus, we consider M. telona a junior synonym of M. ornata, and we propose new combinations: M. ornata ornata Christoph, 1893, M. ornata telona Fruhstorfer, 1908, M. ornata amanica Rebel, 1917, M. ornata capreola Varga, 1967, M. ornata emipunica Verity, 1919, M. ornata enoch Higgins, 1941, M. ornata kovacsi Varga, 1967, M. ornata nigrogygia Verity, 1938, M. ornata ogygia Fruhstorfer, 1907 and M. ornata totila Stauder, 1914 based on the rule of priority. The validity of the species status of M. punica and M. scotosia was confirmed, whereas M. sibina and M. pseudosibina could not be separated from M. phoebe using morphometrics. A new species from Iran (Zagros Mts.) was described as M. zagrosi sp. n. In addition, the whole geographical range of M. ornata was reconsidered and some biogeographical connections were discussed. In M. ornata four morphotypes were found based on genitalia: 1. ‘Western type’: including the Italian, Hungarian and SW Ukrainian populations; 2. ‘Eastern type’: with a much extended distribution ranging from the Balkan Peninsula through Asia Minor to Kazakhstan; 3. ‘The Levant type’ (=M. ornata telona comb. nov.); 4. ‘Northern Iranian type’ (Kopeth Dagh and Elburz Mts.). The distribution of these morphotypes can be attributed to historic separation in distinct glacial refugia.     

Review of the Genus Myrmica in Korea (Hymenptera: Formicidae)

The paper contains a taxonomie review of 12 species of the genus Myrmica occurring in Korea. The following species are under discussion: M. angulinodis Ruzsky, M. carinata Kupyanskaya, M. hyungokae Elmes, M. jessensis Forel, M. kasczenkoi Ruzsky, M. kotokui Forel, M. koreana Elmes, M kurokii Forel, M. lobicornis Nylander, M. ruginodis Nylander, M silvestrii Wheeler, M. sulcinodis Nylander. Twelve species of the genus Myrmica are recognized from Korea, these are revised and a key to their identification is provided. Five species, M. cadusa, M. incurvata, M. saphoshikovi, M. scabrinodis, and M. yoshiokai are questionable to be distributed in Korea, as I have not found any specimens preserved in Korea. The SEM photo and illustrations of the worker of each species are provided.     

A Systematic Comparison of the Anti-Tumoural Activity and Toxicity of the Three Adv-TKs

Adenovirus 5 vectors, known respectively as, the first generation, second generation and oncolytic adenovirus, have been studied extensively in preclinical and clinical trials. However, hitherto few systemic evaluations of the efficacy and toxicity of these adenoviral vectors that have reflected the vertical history of adenovirus based cancer gene therapy strategies have been undertaken. This study has chosen Adv-TK, the well-established adjuvant treatment in cancer, and compared its efficacy and safety with those of the two newly synthesized oncolytic adenovirus vectors encoding the HSV-TK gene, namely M7 and M8. The results obtained showed that systemic administration of 1×10⁸ pfu M7 had an anti-tumour efficacy similar to that of 3×10¹⁰ pfu Adv-TK whilst M8 performed even better. Furthermore, compared to Adv-TK, M7 and M8 reduced the incidence of metastases and substantially prolonged the survival time of the mice xenografted with human orthotopic gastric carcinomas with disseminated metastasis. Even more exciting, however, were the similar toxic and immune safety results obtained from the administration of high doses of M7 or M8 in comparison with Adv-TK in immunocompetent and permissive syrian hamster. The data here exhibit a comprehensive display of the efficacy and safety of the three mutants and provide evidence for the future preclinical use of the M7 and M8 viruses.     

Identification of Meloidogyne Species on the Basis of Head Shape and,Stylet Morphology of the Male

Head shape and stylet morphology of males of 90 populations of M. arenaria, M. hapla, M. incognita, and M. javanica from geographic regions of the world were compared by light microscopy (LM). In addition, stylets of one population each of M. arenaria, M. incognita, and M. javanica and three different chromosomal forms of M. hapla race A and two of race B were excised and examined with a scanning electron microscope (SEM). Differences among species occurred in both head and stylet morphology. Head morphology differed in size and shape of the head cap, annulation of the head region, and width of the head region relative to the first body annule. Differences in stylets occurred in size and shape of the cone, shaft, and knobs. All populations of M. hapla, except one, had similar head morphology, but stylet morphology was different between cytological races A and B. Populations of M. javanica varied with respect to the presence of head annulations. Head shape and stylet morphology of males are recommended as additional characters useful in the identification of root-knot nematodes.     

Heptad motifs within the distal subdomain of the coiled-coil rod region of M protein from rheumatic fever and nephritis associated serotypes of group A streptococci are distinct from each other: Nucleotide sequence of the M57 gene and relation of the deduced amino acid sequence to other M proteins

Streptococcal M protein, a dimeric alpha helical coiled-coil molecule, is an antigenically variable virulence factor on the surface of the bacteria. Our recent conformational analysis of the complete sequence of the M6 protein led us to propose a basic model for the M protein consisting of an extended central coiled-coil rod domain flanked by a variable N-terminal and a conserved C-terminal end domains. The central coiled-coil rod domain of M protein, which constitutes the major part of the M molecule, is made up of repeating heptads of the generalized sequence a-b-c-d-e-f-g, wherein a and d are predominantly apolar residues. Based on the differences in the heptad pattern of apolar residues and internal sequence homology, the central coiled-coil rod domain of M protein could be further divided into three subdomains I, II, and III. The streptococcal sequelae rheumatic fever (RF) and acute glomerulonephritis (AGN) have been known to be associated with distinct serotypes. Consistent with this, we observed that the AGN associated M49 protein exhibits a heptad motif that is distinct from the RF associated M5 and M6 proteins. Asn and Leu predominated in the a and d positions, respectively, in subdomain I of the M5 and M6 proteins, whereas apolar residues predominated in both these positions in the M49 protein. To establish whether the heptad motif of M49 is unique to this protein, or is a general characteristic of nephritis-associated serotypes, the amino acid sequence of M57, another nephritis-associated serotype, has now been examined. The gene encoding M57 was amplified by PCR, cloned into pUC19 vector, and sequenced. The C-terminal half of M57 is highly homologous to other M proteins (conserved region). In contrast, its N-terminal half (variable region) revealed no significant homology with any of the M proteins. Heptad periodicity analysis of the M57 sequence revealed that the basic design principles, consisting of distinct domains observed in the M6 protein, are also conserved in the M57 molecule. However, the heptad motif within the coiled-coil subdomain I of M57 was distinct from M5 and M6 but similar to M49. Similar analyses of the heptad characteristics within the reported sequences of M1, M12, and M24 proteins further confirmed the conservation of the overall architectural design of sequentially distinct M proteins. Furthermore, the heptad motif within subdomain I of the AGN-associated serotypes M1 and M12 was similar to M49 and M57, whereas that of the RF associated M24 was similar to the M5 and M6 proteins. These results clearly demonstrate a correlation between the heptad motifs within the distal coiled-coil subdomain of the M proteins from different streptococcal serotypes and their epidemiological association with the sequelae AGN and RF.