Analysis of applicability of triplet-state emission of molecular hydrogen for spectral diagnostics of a DC discharge

The applicability of emission of the N ³Λ_σ triplet states of molecular hydrogen for spectral diagnostics of the positive column of a dc glow discharge in hydrogen at translational gas temperatures of 360–600 K, specific absorbed powers of 0.8–4.25 W/cm, gas pressures of p = 0.3–15.0 Torr, reduced fields of E/N = 30–130 Td, and electron densities of n _e = 4.0 × 10⁹–6.5 × 10¹⁰ cm^–3 is analyzed by using an advanced level-based semi-empirical collisional?radiative model. It is found that secondary processes make the main contribution to the population and decay of the N ³Λ_σ = a ³Σ⁺ _g , c ³Π _u , g ³Σ⁺ _g , h ³Σ⁺ _g , and i ³Π _g triplet states. The dipole-allowed transitions e ³Σ⁺ _g → a ³Σ⁺ _g , f ³Σ⁺ _g → a ³Σ⁺ _g , g ³Σ⁺ _g and k ³Π _u → a ³Σ⁺ _g can be used for spectral diagnostics of a dc discharge within a simplified coronal model.     

Effects of different batches of iodine on properties of I-hFSH and characteristics of radioligand-receptor assays

Radioiodination of highly purified human follicle-stimulating hormone (hFSH) (4000 IU/mg) was performed every other week for 23 weeks using 2 mCi carrier free Na ¹²⁵I (Amersham Corp., 15 mCi/μg I₂) in the presence of lactoperoxidase. Incorporation of ¹²⁵I into hFSH was determined by the method of [7.]Biochem. J. 89, 114). Hormone binding was studied in vitro under steady-state conditions (16 h, 20°C) using different calf testis membrane preparations having similar receptor characteristics. Each ¹²⁵I-hFSH preparation was characterized for maximum bindability, specific activity of bindable radioligand as determined by self-displacement analysis, and by determination of K_a and R_t. Incorporation of ¹²⁵I into FSH was relatively constant over the large number of experiments (62.4 ± 6.4 μCi/μg; n = 23). By comparison, however, specific radioactivity of the receptor bindable fraction of ¹²⁵I-hFSH was related to the lot of ¹²⁵I utilized, and was significantly (P ≤ 0.01) lower and more variable (28.7 ± 10.5 μCi/μg). Maximum bindability of ¹²⁵I-hFSH was not correlated to specific activity (r = 0.06) but was negatively correlated to hFSH ¹²⁵I incorporation (r = −0.47; P ≤ 0.05). These observations demonstrate the need to assess the quality of each batch of radioligand before undertaking radioligand-receptor assays and suggest that differences in Na¹²⁵I lots affect specific radioactivity of the radioligand and its receptor binding characteristics.     

A mathematical model of kinetics of the biosynthesis of tetracyclines

Summary A mathematical model simulating the behaviour or Streptomyces aureofaciens in batch culture under conditions when tetracyclines are synthesized in excessive amounts has been formulated. The response of the mathematical model to the experimental conditions applied corresponds with data obtained in the experiments. The mathematical model demonstrated that the level of tetracycline production is determined during the period of culture growth beginning with exhaustion of inorganic phosphate from the medium and ending with inhibition of the synthesis of enzymes caused by the synthesized tetracyclines. Further tetracycline synthesis is then proportional to the amount of enzymes synthesized in this interval.List of symbols E Activity of ACT-oxygenase (10×nkat/g) - P Product concentration (mg/l) - k ₁-k ₆ Rate constants - K _S Saturation constant (g sugar/l) - K _I1 Inhibition constant (mg product/l) - K _I2 Inhibition constant (mM phosphate/l) - K _I3 Inhibition constant (mg product/l) - S ₁ Substrate sucrose (g sugar/l) - S ₂ Substrate concentration — phosphate (mM/l) - r _P Specific rate of product formation (mg product/g · h) - r _E Specific rate of enzyme synthesis (10×nkat/g² · h), Expressed by activity units - t Cultivation time (hour) - X Biomass dry weight (g/l) - Y _S/X Yield coefficient - Specific growth rate (h^-1)     

Syntheses of di-hydrocarbyl derivatives of carbonyl phosphine complexes of iron

Complexes cis,trans-Fe(CO)₂(PMe₃)₂RR′ (R = CH₃, R′ = Ph (2); R = CH₃, R′ = CHCH₂ (3); R = CHCH₂, R′ = Ph (4); R = R′ = CHCH₂ (5); R = R′ = CH₃ (6)) were prepared by reaction of cis,trans-Fe(CO)₂(PMe₃)₂RCl (1) with organolithium reagents LiR′. All complexes were characterized in solution by IR and ¹H, ³¹P and, in a few cases, ¹³C NMR mono- and bi-dimensional spectroscopies. Complexes 5 and 6 were structurally characterized by X-ray diffractometric methods. In solution complexes 2, 3 and 4 undergo slowly coupling of the σ-hydrocarbyl substituents leading to Fe(CO)₃(PMe₃)₂ and other decomposition products. Complex 6 was very stable in solution in the absence of nucleophiles and in the solid state. Complex 5 transformed through intramolecular coupling of the vinyl groups into Fe(CO)(PMe₃)₂(η⁴-butadiene) (7), which was characterized in solution by IR and NMR spectroscopies.     

Synthesis of gem-di-C-substituted derivatives of carbohydrates by way of nucleophilic-addition reactions of aldohexofuranoid 3-C-methylene derivatives

Nucleophilic Michael-type additions to aldohexofuranoid 3-C-methylene derivatives, namely, 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-nitromethylene-α-d-ribo-hexofuranose and 3-C-[cyano(ethoxycarbonyl)methylene]-3-deoxy-1,2:5,6-di-O-isopropylidene-α-d-ribo-hexofuranose employing phase-transfer catalysis, afforded novel gem-di-C-substituted sugars. The conversion of 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-methyl-3-C-nitromethyl-α-d-allo-hexofuranose into a 3-C-hydroxymethyl-3-C-methyl derivative with titanium trichloride, and that of the nitromethyl groups of 3-deoxy-1,2:5,6-di-O-isopropylidene-3,3-di-C-nitromethyl-α-d-ribo-hexofuranose, and 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-methyl-3-C-nitromethyl- and -3-C-nitromethyl-α-d-allo-hexofuranose into cyano groups with phosphorus trichloride in pyridine is also described.     

Influence of Volume of Nutrient Agar Medium on Development of Colonies of Marine Bacteria

Zusammenfassung Bei der Bestimmung der Anzahl Bakterien in frisch genommenen Seewasserproben mit dem Plattengußverfahren reduziert eine Agarmenge von über 10 ml die Anzahl sich entwickelnder Kolonien. Die erhaltenen Zahlen sind im allgemeinen am höchsten und die Ergebnisse am besten reproduzierbar, wenn genau 10 ml des Nähragars benutzt wird im Gegensatz zu unbestimmten Mengen zwischen 5 und 30 ml. Obgleich auch andere Faktoren eine Rolle spielen, wird der ungünstige Einfluß von Agarmengen, die merklich größer als 10 ml sind, in erster Linie den langsameren Abkühlungsraten während des üblichen Plattengußverfahrens zugeschrieben. Wenn Nähragar von 42° C bei Raumtemperatur (22–24° C) in Pyrex-Petrischalen gegossen wurde, kühlten 10 ml in ca. 1 min. auf 30° C ab, während 5 bis 24 min. gebraucht wurden, um Agarmengen von 20 bis 50 ml von 42° C auf 30° C abzukühlen. Viele marine Bakterien werden geschädigt, wenn sie Temperaturen ausgesetzt werden, die über 30° C liegen, wobei das Ausmaß der Schädigung von der Einwirkungszeit abhängt. Deswegen ist es überaus wichtig, daß der Agar vor dem Gießen auf 42° C gekühlt wird. Die Abkühlungsrate des Agarmediums in den Platten wird von der Beschaffenheit und der Temperatur der Tischoberfläche, auf der die Platten stchen, beeinflußt.

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Plating the heterogeneous bacteria occuring naturally in samples of raw sea water with volumes of molten nutrient agar exceeding 10 ml reduces the number of colonies which develop. Plate counts on replicate samples of sea water are generally highest and results are more nearly reproducible when 10 ml of nutrient agar is used rather than volumes ranging randomly from 5 to 30 ml. Although other factors are involved, the adverse effects of volumes of nutrient agar appreciable larger than 10 ml are attributed primarily to the slower cooling rates during conventional plating procedures. When nutrient agar medium at 42° C was poured into pyrex Petri dishes at room temperature (22–24° C), 10 ml of the medium cooled to 30° C in about one minute, whereas from about 5 to 24 minutes were required for 20 to 50 ml of the medium to cool from 42° C down to 30 ° C. Many marine bacteria are injured by being subjected to temperatures higher than 30° C, the extent of the injury being a function of time. Therefore, it is of paramount importance that agar be cooled to 42° C prior to pouring. The rate at which agar medium cools in plates is influenced by the composition and temperature of the table top on which the plates rest.

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Contribution from the Scripps Institution of Oceanography, University of California, La Jolla, California.     

The effect of the size of soil structural aggregates on the degree of nitrification

It was experimentally demonstrated that the deviation from linearity exhibited by the dependence of intensity of nitrification on the size of the specific surface of soil structural aggregates is due to deteriorated aeration in the internal space of aggregates of greater diameter. The deteriorated aeration is due to retarded diffusion of oxygen in the aggregates containing greater amounts of moisture. Aggregates isolated from rendzine which displayed a deviation from linearity when their moisture content was equal to twice their maximum hygroscopicity (largersize aggregates produced less nitrates than would correspond to a linear relationship) showed a clear linear dependence as soon as the moisture content dropped to values lower than maximum hygroscopicity.

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Влияние размеров структурных агрегатов почвы на интенсивность нитрификации II. Значение аэрации

Интенсивность нитрификации в почвенных структурных агрегатах различной величины падает с увеличением диаметра агрегатов. Если взять отношение интенсивности нитрификации к размерам специфической поверхности агрегатов (под специфической поверхностью почвенных структурных агрегатов мы понимаем отношение общей внешней поверхности агрегатов опре-деленной фракции к единице вещества), то можно установить, или что падение интенсивности нитрификации протекает равномерно с уменьшением размеров плоцади специфической поверхность агрегатов, или что интенсивность нитри-фикации в агрегатах большего диаметра падает быстрее, чем размеры специфи-ческой поверхности. В этом случае зависимостй интенсивности нитрификации от величины специфической поверхности имеет характер кривой (рис. 1). В предыдущей работе (Сайферт, 1964) нами было высказано предположение, что это явление связано с ухудшением аэрации центральной части крупных агрегатав. Ухудшение аэрации в этих агрегатах, по нашему мнению, обусловлено водяными перегородками, которые здесь почвенная влага образует в результате действия капиллярных сил. Эти перегородки замедляют диффузию кислорода из межагрегатных про-странств внутрь агрегатов. Чтобы доказать правильность нашего предположения, мы устанавливали интенсивность нитрификации в агрегатах раз-личной величины при обычно встречающемся насыщении влагой (19% веса) и при насыщении только до степени гигроскопической влаги. Результаты опытов показали, что в первом случае зависимость интенсивности нитрификации от величины специфической поверхности выражалась кривой (рис. 2), тогда как во бтором случае она имела характер прямой (рис. 4). Ввиду того, что эти результаты полностью подтверждают наше предположение, мы можем считать доказанным, что интенсивность нитрификации в агрегатах боляших диаметров понижается в связи с ухудшением аэрации.

     

Spatial distribution of brood-bearing females of limnetic species of Cladocera

In this study, the spatial distribution of brood-bearing females of five species of limnetic cladocerans (Daphnia cucullata, D. longispina, Bosmina coregoni, B. longirostris, Diaphanosoma brachyurum) in the deep mesotrophic lake in relation to the predation pressure of planktivorous fish (roach Rutilus rutilus, perch Perca fluviatilis, catfish Ictalurus nebulosus, white fish Coregonus albula, bleak Alburnus alburnus), and planktonic invertebrates (cyclopoids Mesocyclops leuckartii, Thermocyclops oithonoides, T. crassus, and cladoceran Leptodora kindtii) as well as some environmental variables was estimated. Most cladocerans showed apparent differences in horizontal distribution (ANOVA F = 0.2–0.45, P < 0.05) in the littoral zone and lack of such differences in the pelagic zone (F = 0.07–0.13, P > 0.05). Vertical distribution of most species, in turn, showed a clear pattern in the pelagic zone (F = 0.31–0.39, P < 0.05) and less regularities in the littoral zone (F = 0.15–029, P > 0.05). The differences in spatial distribution of non-predated and predated species suggest that predation pressure, but not predatory type, was an important factor structuring their distribution. Other factors that affected their distribution were conductivity, dissolved oxygen, TOC and macrophyte biomass; however, most of those variables better explained the distribution of brood-bearing cladocerans in the vertical than horizontal aspect.     

Studies of the morphology of chromosomes of some selected species

Karyotypes of twelve species from twenty-four localities in southern Moravia and one locality in Slovakia were investigated. Their counts or karyotypic formulae are as follows:Chenopodium foliosum (Moench) Ascherson: K (2n)=18=16 A^m+2 B^sm;Astragalus austriacus Jacq.: K (2n)=16=8 A^m+8 B^sm;Astragalus exscapus L.: K (2n)=16=10 A^m+4 B^sm+2 C^st;Astragalus cicer L.: K (2n)=64;Astragalus onobrychis L.: K (2n=64 and K (2n)=64+1;Vicia dumetorum L.: K (2n=14=10 A^m+4 B^sm;Vicia sylvatica L.: K (2n)=14=2 A^m+10 B^sm+2 C^st;Vicia pisiformis L.: K (2n)=12=8 A^m+4 B^sm;Vicia cassubica L.: K (2n)=12=4 A^m+6 B^sm+2 C^st;Vicia cracca L. (from five localities in southern Moravia): K (2n)=28=4 A^m+12 B^sm+12 C^st and K (2n)=28+1=5 A^m+12 B^sm+12 C^st;Vicia cracca L. (from one locality in Slovakia): K (2n)=14=2 A^m+6 B^sm+6 C^st;Vicia tenuifolia Roth: K (2n)=24=4 A^m+16 B^sm+4 C^st;Serratula lycopifolia (Vill.) Kern.: K (2n)=60.     

Synthesis of Fragments of the Peptide Component of Pseudobactin

Pseudobactin is a structurally complex and physiologically important siderophore (microbial iron chelator) from Pseudomonas putida- fluorescens. Various fragments of the unusual peptide component of pseudobactin listed below were prepared by solution-phase peptide synthesis. L -Lys· D -threo-β-OH Asp· L -Ala· D -allo-Thr· L -Ala L -Lys· D -threo-βOH Asp· L -Ala· D -allo-Thr D -threo-β-OH Asp· L -Ala· D - allo-Thr· L -Ala· D -N-OH-cycloOrn D -threo-β-OH-Asp· L -Ala· D -allo-Thr· L -Ala L -Ala· D -allo-Thr· L - Ala· D -N-OH-cycloOrn A class of related peptides named pseudomycins have shown promising antifungal activity. To examine if these peptide fragments above would elicit similar activity, the fragments were tested and found to have no antifungal activity in limited bioassays.     

Effect of temperature on the duration of larval and pupal stages of two species of sciomyzid flies, predators of the snail Lymnaea truncatula

The duration of larval and pupal stages of two species of predatory flies was investigated at five constant temperatures. Ilione albiseta (Scopoli): Mean duration of first and second instars was shortest at 23°C and there was 100% survival of first instar larvae at all temperatures. Mean third instar larval duration decreased from 104 days at 17°C to 27.5 days at 26°C. Total percentage larval survival was greatest at 17°C and least at 26°C. Mean pupal duration decreased as temperature increased and this occurred also under outdoor conditions. Pherbellia cinerella (Fallén): As temperature increased mean larval duration decreased but the percentage of larvae pupating also decreased (100% at 14°C, 33.3% at 26°C). There was a trend for shorter mean pupal durations at higher temperatures.

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Résumé L'action de la température a été examinée à 14, 17, 20, 23 et 26°C. Les 2 espèces sont prédatrices de L. truncatula, vecteur de la douve du foie en Irlande, où elle provoque à l'àgriculture une perte évaluée à 10 millions de livres par an. Les données recuellies en conditions contrôlées du laboratoire doivent permettre de définir les conditions optimales pour l'élevage continu de ces espèces. Ceci est indispensable pour évaluer, dans la nature leurs potentialités pour la lutte biologique. Ilione albiseta: C'est à 23°C que le développement des larves de premier et second stades sont les plus brefs; la survie du premier stade est totale à toutes les températures constantes examinées. La durée moyenne du 3ème stade décroît de 104 jours à 17°C jusqu'à 27,5 jours à 26°C. Le taux de survie total est plus élevé à 17°C qu'à 26°C. La durée moyenne de la nymphose diminue quand la température croît, et ceci se produit aussi à la température ambiante extérieure. On réduit de moitié la durée du développement de l'éclosion de l'oeuf à l'apparition de l'adulte, entre la nature et le laboratoire, en utilisant respectivement: 23°, 17° et 26°C pour les premier et second stades, le troisième stade, la nymphé. Cela devrait aider à multiplier la souche pour la lutte biologique. Pherbellia cinerella: Avec élévation de la température la durée du développement larvaire diminue, mais aussi le nombre de larves parvenant à la pupaison (100% à 14° et 33,3% à 26°C). La nymphose tendait à être plus brève aux températures les plus élevées.

     

Comparison of the profiles of non-glycosylated triterpenoids from leaves of plants of selected species of genus Dioscorea

Remarkable qualitative and quantitative differences in non-glycosylated triterpenoid profiles of twelve Dioscorea spp. leaves were demonstrated with the use of GC–MS/FID analysis. The total content of tetracyclic triterpenoids and their esters ranged from 397 μg/g of dry leaf weight in D. bulbifera to 762 μg/g d.w. in D. discolor and 777 μg/g d.w. in D. alata. Three main phytosterols, i.e. campesterol (1), sitosterol (2) and stigmasterol (3) were found in extracts from all analyzed species in total amount ranging from 316 μg/g in D. bulbifera to 676 μg/g of dry leaf weight in D. hispida, with either sitosterol (2) or stigmasterol (3) as predominant in the profile. Extracts from D. hispida and D. purpurea leaves were distinguished from the others by particularly high amount of campesterol (1). In the majority of the species, except for D. caucasica, other tetracyclic triterpenoids were found: cycloartanol (4), 24-methylenecycloartanol (5) and cycloeucalenol (6). Less common steroids, stigmastan-3-en-6β-ol (7) and ergosta-7,22-dien-3β-ol (8) were detected in D. japonica. The significant content (992 μg/g) of pentacyclic triterpenoids of ursane, oleanane, taraxastane and taraxerene (friedooleanane)-type carbon skeletons, i.e. α-amyrin (9), β-amyrin (10), taraxasterol (11) and taraxerol (12), respectively, was found in D. caucasica. The obtained results supplement the knowledge of biochemical diversity of Dioscorea genus.     

Lack of interchangeability of Hfq-like proteins

Hfq is an RNA-binding protein that participates in the regulatory activity of small non-coding RNAs (sRNAs) in many species of bacteria. Hfq protein was first crystallized from Staphylococcus aureus and this crystal structure constitutes a hallmark for bacterial Sm-like proteins. Paradoxically, however, the functional relevance/role of S. aureus Hfq (Hfq_SA) remains uncertain, as growing evidence suggests that the hfq_SA gene is expressed at very low levels or unexpressed in many S. aureus strains. To gather further insight, in the present work we exchanged the structural portion of the hfq gene of Salmonella enterica serovar Typhimurium (hfq_STM) with hfq_SA and analyzed the effects of the replacement on various Hfq-related phenotypes. Our results show that the replacement strain – in spite of expressing Hfq_SA at levels comparable to Hfq_STM in wild-type Salmonella – behaves as an hfq null mutant in three discrete small RNA-mediated regulatory responses. These defects correlate with an abrupt reduction in the intracellular concentration of sRNAs, as observed in an hfq null mutant. Failure of Hfq_SA to protect Salmonella sRNAs from degradation suggests that Hfq_Sa does not bind to these sRNAs. A parallel study with the Borrelia burgdorferi hfq gene (hfq_BB) gave essentially identical results: when made from a single copy chromosomal gene, Hfq_BB fails to substitute for Hfq_STM in sRNA-mediated regulation.     

Potentiation of effect of PKA stimulation of Xenopus CFTR by activation of PKC: role of NBD2

Activity of the human (h) cystic fibrosis transmembrane conductance regulator (CFTR) channel is predominantly regulated by PKA-mediated phosphorylation. In contrast, Xenopus (X)CFTR is more responsive to PKC than PKA stimulation. We investigated the interaction between the two kinases in XCFTR. We expressed XCFTR in Xenopus oocytes and maximally stimulated it with PKA agonists. The magnitude of activation after PKC stimulation was about eightfold that without pretreatment with PKC agonist. hCFTR, expressed in the same system, lacked this response. We name this phenomenon XCFTR-specific PKC potentiation effect. To ascertain its biophysical mechanism, we first tested for XCFTR channel insertion into the plasma membrane by a substituted-cysteine-accessibility method. No insertion was detected during kinase stimulation. Next, we studied single-channel properties and found that the single-channel open probability (P_o) with PKA stimulation subsequent to PKC stimulation was 2.8-fold that observed in the absence of PKC preactivation and that single-channel conductance () was increased by 22%. To ascertain which XCFTR regions are responsible for the potentiation, we constructed several XCFTR-hCFTR chimeras, expressed them in Xenopus oocytes, and tested them electrophysiologically. Two chimeras [hCFTR NH₂-terminal region or regulatory (R) domain in XCFTR] showed a significant decrease in potentiation. In the chimera in which XCFTR nucleotide-binding domain (NBD)2 was replaced with the hCFTR sequence there was no potentiation whatsoever. The converse chimera (hCFTR with Xenopus NBD2) did not exhibit potentiation. These results indicate that potentiation by PKC involves a large increase in P_o (with a small change in ) without CFTR channel insertion into the plasma membrane, that XCFTR NBD2 is necessary but not sufficient for the effect, and that the potentiation effect is likely to involve other CFTR domains. cystic fibrosis; chloride channel; protein kinases; ATP binding cassette proteins     

CD studies of double-stranded polydeoxynucleotides composed of repeating units of contiguous homopurine residues

Double-stranded synthetic polydeoxynucleotides of the general form poly[d(G_nC_n)] · poly[d(G_nC_n)], poly[d(G_nC)] · poly[d(GC_n)], and poly[d(A_nT_n)] · poly[d(A_nT_n)] have been synthesized. When n = 4 or larger, the CD spectra of polymers of the form poly[d(G_nC_n)] · poly[d(G_nC_n)] or poly[d(G_nC)] · poly[d(GC_n)] closely resemble the spectrum of poly[dG] · poly[dC], suggesting that a string of four continguous guanosine residues is sufficient to induce a conformation resembling that of the polypurine · polypyrimidine. With polymers of the form poly[d(A_nT_n)] · poly[d(A_nT_n)], however, the CD spectrum only gradually approaches that of poly[dA] · poly[dT].     

Kinetics of formation of ferrioxamine B

Stopped-flow kinetic studies of the formation of ferrioxamine B were performed. Formation of the complex follows the rate law

where K_a is the acid dissociation constant of the iron(III) aquo species in 0.1 M formate buffer. At 25°C k₁ = 3.94 × 10²M^?1 sec^?1, k₂K_a = 1.18 × 10^?1 sec^?1, k₃ = 3.6 × 10^?1 sec^?1. Activation parameters for k₁ are ΔH^≠ = 11.7 kcal mole^?1 and ΔS^≠ = ?8 cal K^?1 mole^?1. An associative mechanism is proposed. Attachment of the first chelate ring is the slow step and favorably positions the second chelate ring for attachment. Coordination of two chelate rings favorably positions the third chelate ring for attachment. These results are compared to kinetics of formation of model complexes and to a previous study of the formation of ferrioxamine B in which attachment of the third chelate ring was proposed as the slow step     

Seasonal study of the fungal biota of the fur of dogs

During a one year period, 944 dogs from the Municipal kennel of Barcelona were examined to detect animals with suspected dermatophytosis. Only a few animals (1.8%) presented skin lesions but none of them had dermatophytosis. A representative number of dogs without visible skin lesions (n=172), selected at random, were used to carry out a seasonal study of the mycobiota of their fur. Fifteen isolates belonging to the genera Microsporum and Trichophyton were isolated from 14 of the 172 (8.1%) dogs without lesions. The identity of these fungi was Microsporum gypseum (6/15), Trichophyton terrestre (4/15), M. canis (2/15), M. cookei (2/15) and Trichophyton ajelloi (1/15) (one strain each of M. gypseum and T. ajelloi were isolated from one dog). Species of Penicillium (% prevalence=89.5%), Alternaria (86.6%), Cladosporium (84.9%), Aspergillus (77.3%), Scopulariopsis (65.7%) and Chrysosporium (64.5%) were the most prevalent. No significant differences in the fungal biota were observed with respect to age, gender, hair length or between mixed and pure breed dogs. A large number of isolates, including species belonging to the genera Beauveria, Chrysosporium, Malbranchea and Scopulariopsis, that macroscopically and/or microscopically resemble dermatophytes and may be mistaken for them, produced a red color change in Dermatophyte Test Medium. No significant seasonal difference was detected among the isolates belonging to the the most frequently encountered genera, with the exception of Scopulariopsis (higher in summer and autumn) and Chrysosporium (higher in summer). Species from other genera, with lower occurrence also presented significant differences in their seasonal distribution. Arthrinium, Aureobasidium, Chaetomium and Phoma spp. presented maximum prevalence peaks in spring, Fusarium, Paecilomyces, Phoma and Rhizopus spp. in summer and Geotrichum and Mucor spp. in autumn. The Microsporum and Trichophyton species were more frequently isolated in summer.