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PubMed2001

Seasonal variation in leaf glucosinolates and insect resistance in two types of Barbarea vulgaris ssp. arcuata.

Leaves from natural populations of Barbarea vulgaris ssp. arcuata (Brassicaceae) in Denmark were examined for glucosinolate content and resistance to the crucifer specialist flea beetle Phyllotreta nemorum. Two types of the plant (P- and G-type) could be recognized. Leaves of the G-type contained the glucosinolates (only side chains mentioned): (S)-2-hydroxy-2-phenylethyl- (2S), indol-3-ylmethyl- (4) and in trace amount (R)-2-hydroxy-2-phenylethyl- (2R), 2-phenylethyl- (1) and 4-methoxyindol-3-ylmethyl- (5). Leaves of the P-type were dominated by 2R and 4, and had only trace amounts of 1, 2S, and 5 but contained in addition the previously unknown (R)-2-hydroxy-2-(4-hydroxyphenyl)ethyl- (3R). The epimer, (S)-2-hydroxy-2-(4-hydroxyphenyl)ethyl- (3S) was found in populations believed to be hybrids, and in B. orthoceras. 2S, 2R, desulfo 2S,-2R, -3S and -3R were isolated and identified by NMR and MS. Acylated glucosinolates or allylglucosinolate were not detected in leaves. The glucosinolate content in August was variable, 3-46 micromol/g dry wt, but was low in most populations, 3-15 micromol/g dry wt. In general, the glucosinolate content increased during the autumn, to 35-75 micromol/g dry wt in November. The G-type was resistant to neonate larvae of Phyllotreta nemorum in August and September (survival in 3-day bioassay typically 0%), and gradually lost the resistance in October and November (survival in 3-day bioassay 40-90%), and there was no correlation between glucosinolate content and resistance. Neither did glucosinolates explain the difference in resistance between the P-type (always susceptible) and the G-type (resistant in the summer season).

Acylation↗
PubMed1997

Sir Charles James Martin MB FRS: Australian serpents and Indian plague, one-hundred years ago.

In 1891 as Demonstrator in Physiology at the University of Sydney, Charles Martin began the first systematic study of the chemical and physiological properties of the venoms of the Australian elapid species, Pseudechis porphyriacus and Notechis scutatus. Two major constituents were detected: a large coagulable protein which was associated with intravascular clotting, and a small proteinaceous molecule, an albumose, associated with neurotoxicity. Martin designed and constructed a high-pressure gelatin membrane ultrafilter for fractionation of venom. His studies indicated that certain physiological actions and clinical symptoms were related to the faster rate of diffusion within the tissue space of a neurotoxic constituent relative to a clotting constituent. Extending this work to toxin-antitoxin relationships, Martin provided evidence that antitoxin was a large molecule with slow diffusibility in tissue and advised the administration of curative serum (including diphtheria antitoxin) by intravenous injection. In 1903, Martin returned to London as Director of the Lister Institute of Preventive Medicine. He was soon involved in the planning of scientific work to be undertaken by the Commission for Investigation of Plague in India as the disease continued to ravage the subcontinent. Detailed epidemiological studies of possible factors involved in the spread of Pasteurella pestis showed, unequivocally, that infected rat fleas were the vector of transmission from rats to humans.

Australia↗
PubMed2001

Toxicity of benzotriazole and benzotriazole derivatives to three aquatic species.

Benzotriazole and its derivatives comprise an important class of corrosion inhibitors, typically used as trace additives in industrial chemical mixtures such as coolants, deicers, surface coatings, cutting fluids, and hydraulic fluids. Recent studies have shown that benzotriazole derivatives are a major component of aircraft deicing fluids (ADFs) responsible for toxicity to bacteria (Microtox). Our current research compared the toxicity of benzotriazole (BT), two methylbenzotriazole (MeBT) isomers, and butylbenzotriazole (BBT). Acute toxicity assays were used to model the response of three common test organisms: Microtox bacteria (Vibrio fischeri), fathead minnow (Pimephales promelas) and water flea (Ceriodaphnia dubia). The response of all the three organisms varied over two orders of magnitude among all compounds. Vibrio fischeri was more sensitive than either C. dubia or P. promelas to all the test materials, while C. dubia was less sensitive than P. promelas. The response of test organisms to unmethylated benzotriazole and 4-methylbenzotriazole was similar, whereas 5-methylbenzotriazole was more toxic than either of these two compounds. BBT was the most toxic benzotriazole derivative tested, inducing acute toxicity at a concentration of < or = 3.3 mg/l to all organisms.

Animals↗
PubMed2003

Responses in sediment bioassays used in the Netherlands: can observed toxicity be explained by routinely monitored priority pollutants?

In order to identify the cause of toxicity in sediments and suspended matter, a large number of samples with different degrees of contamination was taken at various locations in The Netherlands. Standard acute bioassays were carried out with the bacterium Vibrio fischeri, the rotifer Brachionus calyciflorus and the anostracan Thamnocephalus platyurus. Chronic standard tests were performed using the water flea Daphnia magna and larvae of the midge Chironomus riparius. Some novel bioassays were performed as well. Most toxic effects observed in standard bioassays with sediments from polluted sediments (class 3 and 4 on a scale of 0-4 according to the Dutch criteria) could be partly explained by toxic concentrations of known persistent priority pollutants, mainly heavy metals and occasionally polycyclic aromatic hydrocarbons. In some of the samples, ammonia toxicity was a confounding factor during testing. Suspended matter from the Meuse river at Eijsden, which may be considered as 'new' sediment (pollution class 2), was moderately to highly toxic in almost all bioassays. This could have been associated with a combination of heavy metals, PAHs and ammonia. At two locations from the Lake IJssel area with no apparent persistent pollution, moderate and strong effects were nonetheless observed in invertebrate tests. This might have been due to agricultural run-off of pesticides, which are not routinely measured in sediments. A few effects on V. fischeri in canals and a small stream could not be explained with standard chemical analysis, but seemed associated with the outlets of sewage water treatment plants and industrial effluents. Additional chemical analysis of pore water samples from five selected sediments yielded more identified substances such as phtalates, decanes, cosanes and fragrances, but it was estimated that their contribution to the effects observed on V. fischeri, D. magna and C. riparius was negligible.

Animals↗
PubMed2003

Juvenile hormone agonists affect the occurrence of male Daphnia.

The water flea Daphnia magna reproduces primarily by cyclic parthenogenesis. Environmental stimuli that signal a change to adverse conditions induce the organisms to switch from parthenogenesis to gamogenetic reproduction. During the gamogenetic period, they produce male daphnids and dormant resting eggs, which can survive prolonged periods of environmental adversity. However, little is known about the mechanisms associated with the switch from parthenogenesis to gamogenetic reproduction. We investigated the effects of several juvenoids on sex determination in Daphnia. Females less than 24 h old were exposed to various concentrations of the test substance and were observed for 21 days. It was found that they can trigger the appearance of male daphnids: the percentage of males in the population increases to a level greater than what occurs under ordinary environmental conditions. We found that methylfarnesoate, juvenile hormone III, methoprene, and the phenoxyphenoxy derivatives pyriproxyfen and fenoxycarb (both insecticides) reduced the production of offspring and produced sex ratios dominated by male daphnids. Pyriproxyfen and fenoxycarb showed striking effects at low concentrations. Exposure to either of these chemicals at a concentration of 330 ngl(-1) caused adult females to produce almost all male neonates. Methylfarnesoate, juvenile hormone III, and methoprene showed an effect in inducing male production at higher concentrations (3.7 x 10(3), 3.3 x 10(5), and 1.3 x 10(5) ngl(-1), respectively). Our findings suggest that juvenile hormone agonists, including some insecticides, affect the chemical signaling responsible for inducing the production of male offspring.

Animals↗
PubMed1998

Effects of dissolved organic matter (DOM) on the bioconcentration of organic chemicals in aquatic organisms--a review.

Current knowledge on the effects of dissolved organic matter (DOM) on the bioconcentration of organic chemicals in aquatic animals (water fleas, mussels, amphipods and fish) is summarized. A graphical representation of the available data gives an overview of the magnitude of the observed effects. Most of the studies have shown decreases in bioconcentration in the presence of DOM (2 to 98% relative to DOM-free controls). However, at low DOM levels, up to 10 mg/L, also enhancements of bioconcentration due to DOM, ranging from 2 to 303% have been reported. Generally, the change in BCFW (Bioconcentration factor on a wet weight basis) per mg/L DOC was most pronounced at low levels of DOC. The data also show that DOM from different sources with different characteristics and quality can lead to substantial variations in the bioconcentration of organic compounds at comparable levels of DOC. While decreases in bioconcentration have generally been attributed to a lack of bioavailability of DOM-bound chemical, no mechanisms have been proposed to explain increased uptake of xenobiotics caused by DOM.

Animals↗
PubMed2004

Ectoparasites--the underestimated realm.

CONTEXT: Ectoparasitoses (infestations with parasites that live on or in the skin) can cause considerable morbidity. Whereas pediculosis and scabies are ubiquitous, cutaneous larva migrans and tungiasis (sand-flea disease) occur mainly in hot climates. The prevalence of ectoparasitoses in the general population is usually low, but can be high in vulnerable groups. Scientific knowledge on how to deal best with parasitic skin diseases in different settings is scanty, and evidence-based measures for control are not available. For head lice and scabies the situation is daunting, because resistance of Pediculus humanus capitis and Sarcoptes scabiei to insecticides is spreading and unpredictable. STARTING POINT: J Hunter and S Barker reported different patterns of resistance in schoolchildren in Brisbane, Australia: full resistance to malathion, permethrin, and pyrethrum in two schools, whereas head lice were susceptible to malathion and, to a lesser extent, to pyrethrums in three other schools (Parasitol Res 2003; 90: 476-78). K Yoon and colleagues found different resistance patterns in the USA and Ecuador (Arch Dermatol 2003; 139: 994-1000). Head lice from Florida were less susceptible to permethrin than those from Texas, and parasites from Ecuador were susceptible to both insecticides tested. WHERE NEXT? The occurrence of resistant pediculosis and scabies is expected to increase numerically and geographically. Clinicoepidemiological studies are urgently needed to identify the factors which govern the emergence and spread of strains of P humanus capitis and S scabiei that are resistant to insecticide or acaricide. Oral treatment with ivermectin could substitute for topically applied compounds, particularly in resource-poor communities where polyparasitism is common. A better understanding of local epidemiology is required to develop control measures. This knowledge has to be applied in combination with environmental sanitation, health education, and culturally acceptable interventions that are affordable by the underprivileged.

Drug Resistance↗
PubMed1995

Eradication of dracunculiasis from Pakistan.

In 1986 the World Health Organization targeted dracunculiasis (Guinea-worm disease), which seriously impairs socioeconomic development in 16 African countries, India, Pakistan, and Yemen, to be eradicated globally. The target date for eradication by the end of 1995 was established in 1991. Pakistan eradicated dracunculiasis from the country in October, 1993, after a national campaign which began in 1987 with a nationwide village-by-village search for cases. The infection, which is transmitted by drinking water from ponds containing infected water fleas, was eradicated by using health education, cloth filters, and the cyclopsicide, temephos; and in the later stages, by case containment. Methods pioneered in Pakistan's National Guinea Worm Eradication Program are now being applied in remaining endemic countries.

Communicable Disease Control↗
PubMedDate not supplied

Relation between responses in the neutral red retention test and the comet assay and life history parameters of Daphnia magna.

Responses of the neutral red retention (NRR) assay as test for lysosomal stability and the comet assay as test for DNA integrity were measured in the water flea, Daphnia magna, and compared with mortality and effects on population growth rate during short- or long-term exposure to seven different toxicants. The NRR test and the comet assay were performed with fresh preparations of pieces of tissue from the digestive tract or with cell preparations from whole daphnias. Five toxicants caused responses of the NRR test or the comet assay after short-term exposure at concentrations below the acute toxicity level. Preliminary results of long-term exposure experiments suggest that these biomarker responses can be related to chronic effects on survival and/or reproduction of D. magna. This type of research should provide the basis for future use of the NRR test and the comet assay as early warning biomarkers for effects of toxicants on Daphnia populations.

Animals↗
PubMed2003

Expression and characterization of recombinant canine IL-13 receptor alpha2 protein and its biological activity in vitro.

Our previous study showed that recombinant canine IL-13 (rcaIL-13) stimulated production of allergen-specific IgE in vitro by peripheral blood mononuclear cells (PBMC) from flea allergen-sensitized dogs. This has also been demonstrated using human IL-13 (huIL-13) and PBMC isolated from human allergy patients. The stimulatory activity of rcaIL-13 was specifically inhibited by a fusion protein of the extracellular domain of canine IL-13Ralpha2 and the Fc fragment of canine IgG heavy chain (rcaIL-13Ralpha2-Fc). In this communication, we report the construction and expression of a non-fused recombinant extracellular domain of canine IL-13Ralpha2 (rcaIL-13Ralpha2) in an E. coli expression system. The E. coli expressed rcaIL-13Ralpha2 was isolated in inclusion bodies, then solubilized in buffer containing denaturants and reducing agents. After refolding and purification, the biological activity of rcaIL-13Ralpha2 was found in the monomer fraction resulting from gel filtration and ion exchange chromatographies. Biological activity of purified rcaIL-13Ralpha2 was demonstrated by the specific inhibition of rcaIL-13 activity in a TF-1 cell proliferation assay. Additionally, rcaIL-13Ralpha2 was found to be active in neutralizing rcaIL-13 induced upregulation of IgE mRNA levels in PBMCs of "high IgE" dogs, which have been bred to exhibit a predisposition for high IgE production and are used as a model for allergic asthma. The data confirm our previous report that the regulatory effects of IL-13 on IgE production in canine PBMCs are similar to those reported in humans. Thus, allergic dogs, such as the "high IgE" producing dogs, may be excellent models for research on IgE-mediated diseases in humans.

Allergens↗
PubMed2001

Recombinant canine IL-13 receptor alpha2-Fc fusion protein inhibits canine allergen-specific-IgE production in vitro by peripheral blood mononuclear cells from allergic dogs.

Human IL-13, like IL-4, is involved in the regulation of B-cell development, IgE synthesis and allergic responses. However, because IL-13 does not affect either murine Ig class switching or IgE production in vitro, the use of murine models to study the role of IL-13 in IgE-mediated diseases has been limited. In this communication, we report that recombinant protein of canine IL-13 (rcaIL-13) stimulates production of allergen-specific-IgE in vitro by peripheral blood mononuclear cells (PBMC) from flea allergen-sensitized dogs, and that this stimulation activity is specifically inhibited by recombinant protein of canine IL-13Ralpha2 and Fc fragment of canine IgG heavy chain (rcaIL-13Ralpha2-Fc). The data suggest that the regulatory effects of IL-13 on IgE production in canine PBMC are similar to those reported in humans. Thus, canine IL-13 may be a central mediator of allergic diseases in dogs, and allergic dogs may be excellent models for research on IgE-mediated diseases in humans.

Amino Acid Sequence↗
PubMed1997

Aspects of the humoral immune response to Staphylococcus intermedius in dogs with superficial pyoderma, deep pyoderma and anal furunculosis.

Bacterial infection (pyoderma) of the canine skin is largely caused by Staphylococcus intermedius and may be a superficial or deep infection. Pyoderma may be a primary, idiopathic disease or secondary to a range of other dermatological disorders. In this study, the serum concentrations of IgG, IgA, antistaphylococcal IgG and antistaphylococcal IgA were measured by ELISA in normal dogs (n = 22), dogs with idiopathic deep pyoderma (n = 22), atopic dermatitis and superficial pyoderma (n = 24), atopic dermatitis without pyoderma (n = 25), flea bite dermatitis with superficial pyoderma (n = 8), pustular demodicosis (n = 8) and German shepherd dogs with anal furunculosis (n = 28). The serum IgG was significantly increased in dogs with atopy and superficial pyoderma (p < 0.001), and lower than normal in dogs with idiopathic deep pyoderma (p < 0.015). The concentration of serum IgA was significantly lower than normal in dogs with atopy uncomplicated by pyoderma (p < 0.015). The concentration of antistaphylococcal IgG in all clinical sera was significantly elevated (p < 0.001) when compared to normal dogs but concentrations of antistaphylococcal IgA were no greater than in normal dogs. Western blotting analysis for determination of the specificity of serum IgG antistaphylococcal antibody revealed that there were nine major epitopes. Discriminant analysis demonstrated that particular combinations of these epitopes were recognised more frequently by sera from dogs in different clinical groups.

Animals↗
PubMed1998

Allergen-specific IgE and IgGd antibodies in atopic and normal dogs.

Intradermal skin tests (IDSTs) were performed on 65 atopic and 24 normal dogs. The levels of allergen-specific IgE and IgGd antibodies were determined in serum samples by enzyme-linked immunosorbent assay (ELISA) using the same 12 allergens that were used in the IDST on normal dogs. The correlation between the levels of IgE and IgGd to Dermatophagoides farinae (DF) and Dermatophagoides pteronyssinus (DP) was examined. The sensitivity, specificity and positive and negative predictive values of allergen-specific IgE and IgGd levels in the total dog population were also compared. Results were consistent and reproducible for 9/12 allergens, but in the case of house dust, flea and Alternaria tenuis, a less discriminating standard curve and the fact that the negative control gave positive results, suggests non-specific binding and that these allergens are complex and should not be employed without further purification. A high percentage of atopic dogs had positive IDSTs and detectable IgE and IgGd antibodies to DF, DP and house dust. Similar results were obtained in the normal dog population. There were significant correlations between allergen-specific IgE and IgGd levels to DF and DP. However, in contrast to IgE, allergen-specific IgGd in normal dogs was higher than in atopic dogs. Furthermore, a high percentage of the atopic population had detectable IgGd to unrelated allergens, despite negative IDSTs. Overall, the negative predictive values were similar for both IgE and IgGd. Sensitivities were higher in the allergen-specific IgGd assays, but the specificities and positive predictive values were higher in the allergen-specific IgE assays. In conclusion, the concordance of IDSTs with ELISA results to DF and DP in normal dogs without clinical signs implied the possible heterogeneity of IgE in dogs. The presence of IgGd directed against apparently irrelevant allergens in atopic patients and the high levels of IgGd in normal dogs to the most common allergens, DF and DP, implied an uncertain role of IgGd in canine atopic disease. Therefore, the detection of allergen-specific IgE is a more useful adjunct to the diagnosis of atopic disease in the dog than IgGd.

Allergens↗
PubMed1999

Canine atopic dermatitis in Greece: clinical observations and the prevalence of positive intradermal test reactions in 91 spontaneous cases.

Atopic dermatitis was diagnosed in a total of 91 dogs by combining the compatible historical evidence and clinical signs with the presence of one or more positive intradermal test reactions well correlated with the exposure to the aeroallergens and the seasonality of the clinical signs. Compared to the general hospital population Yorkshire terriers, Chinese Shar-Peis and cocker spaniels showed a strong predilection. No such predilection was found regarding the sex of the animals. The age of the dogs at the onset of the clinical signs ranged from 2 months to 8 years (median: 2.5 years). Moderate to severe pruritus, noticed in all the 91 dogs, was either localized (29/91) or generalized (64/91) and non-seasonal (43/91), seasonal (19/91) or of unknown seasonality (29/91). The most common cutaneous lesions included erythema, hyperpigmentation, hypotrichosis and crusts; their body distribution was generalized (64%) or localized (36%) with the feet as the most common site of involvement. Five dogs that had unlesional skin were significantly younger and had been pruritic for a shorter period of time compared to the majority of our study population. Otitis externa (43/91) and bacterial pyoderma (30/91) were the most common conditions associated with atopic dermatitis, while the prevalence of Malassezia dermatitis was very low (2/91). Of the other allergic skin diseases flea allergic dermatitis was the most common (29/91) followed by food hypersensitivity (2 out of the 15 dogs tested). The majority of the dogs demonstrated multiple sensitivities to the 50 aeroallergens tested, while domestic mites (77/91), and particularly Dermatophagoides farinae (64/91), were the most commonly implicated. The total number of the positive intradermal test reactions was increasing parallel to the age of the dogs but it was negatively associated with the presence of skin lesions on the carpal and tarsal joints.

Animals↗
PubMed2003

Biotransformation and bioconcentration of pyrene in Daphnia magna.

Water fleas (Daphnia magna) were exposed to [14C]pyrene in the presence and absence of piperonyl butoxide (PBO), a general cytochrome P450 (CYP) inhibitor, in organic carbon-free artificial freshwater (AFW, DOC<0.2 mg l(-1)) and in natural lake water (DOC=19.9 mg l(-1)) for 24 h. The bioconcentration of total radioactivity after 24 h exposure was 50% lower in the natural lake water, indicating decreased bioavailability of pyrene by the dissolved organic matter. However, the proportions of parent compound were only ca. 12 and 19% of the total body burden in daphnids exposed in AFW and natural lake water, respectively. Therefore, the tissue concentration of the parent pyrene was not significantly different in the daphnids exposed in the two different waters. Due to extensive biotransformation the bioconcentration factor (BCF) of parent pyrene was only 16 and 23% of the BCF calculated on the basis of total radioactivity in the daphnids in AFW and natural lake water, respectively. The proportion of parent pyrene was significantly higher (over 60%) in the daphnids exposed simultaneously to PBO, which indicates the involvement of CYP monooxygenases in the biotransformation. Furthermore, increasing PBO concentration decreased the accumulation of total radioactivity in AFW but not in the natural lake water. The data demonstrate capability and importance of CYP monooxygenases in biotransformation of polycyclic aromatic hydrocarbons in D. magna.

Animals↗
PubMed1997

The complete nucleotide sequence of rabbit haemorrhagic disease virus (Czech strain V351): use of the polymerase chain reaction to detect replication in Australian vertebrates and analysis of viral population sequence variation.

The complete nucleotide sequence of the Czech strain of rabbit haemorrhagic disease virus (RHDV) was determined to be 7437 nucleotides in length with a 5-terminal non-coding region of 9 nucleotides and a 3'-terminal non-coding region of 59 nucleotides. Two open reading frames (ORFs) were found within this sequence coding for polypeptides of 2344 (nucleotides 10-7044) and 117 amino acids (nucleotides 7025-7378). The sequence of this isolate was approximately 1% different from that reported by Meyers et al., having 78 nucleotide changes which resulted in 30 amino acid differences, the majority of these clustering in the N-terminus of the large ORF and the middle of the viral coat protein. Only a single conservative amino acid change was seen in the smaller 3'-terminal ORF. Since the virus cannot at present be propagated in tissue culture, but isolated only after replication in rabbits, the reported sequence must be considered as a consensus sequence from the viral population. To gain some understanding of the possible sequence diversity within this virus population, 97 clones were sequenced from a polymerase chain reaction (PCR) fragment to determine the sequence diversity of the virus population. Four major classes of variant were described with mutations generally in the third base position of codons. A nested reverse transcriptase (RT) PCR (using sequence derived for the coat protein of RHDV) was used to determine the presence or absence of RHDV inoculated into non-host animal species. No replication of the virus was detected in 28 different vertebrate species other than rabbits. PCR tests on both mosquitoes and fleas feeding on RHDV infected rabbits were positive. The RT-PCR test was more sensitive when compared with an antigen capture ELISA to detect the presence of genomic RNA/or virus in infected rabbits.

Amino Acid Sequence↗
PubMed2000

Mites and birds: diversity, parasitism and coevolution.

Ectoparasites play important roles in the lives of birds. Among these parasites, mites offer unique potential because of their extraordinary ecological and evolutionary diversity. However, the basic biology of most mites is poorly understood, and misleading extrapolations are sometimes made from better studied systems involving lice and fleas. Most importantly, not all bird-associated mites are parasitic; indeed, recent research suggests that some might even be beneficial. Here, we summarize what is known about the diversity of bird-mite relationships, and highlight how mites provide an ideal tool for the study of host life histories, sexual selection, immunocompetence and cospeciation.

Journal Article↗
PubMed1986

In vivo isolation and maintenance of some wild strains of European hard tick spirochetes in mammalian and arthropod hosts. A parasitologist's view.

Methods and results of isolation and experimental maintenance of Borrelia strains from indigenous Ixodes ricinus ticks are described. Out of 12 different proved rodent species and breeding variants the mongolian jird or gerbils (Meriones unguiculatus) offers most perfectly all the necessary qualities to produce a transitory not progressive microscopically apparent spirochetemia when splenectomized previously. Using a laboratory breed of Ixodes ricinus the occurrence of transstadial and transovarial transmission could be confirmed in the vector tick. Each developmental stage of ticks can be infected via blood ingestion on spirochetemic mammalian hosts but each stage can infect vice versa its blood donors equally well. Needle borne transmissions from gerbil to gerbil by i.p. administration of infected blood are particularly successful after previous deep-freezing and cryopreservation of the blood samples or tissue suspensions. Attempts are described to infect other tick species than I. ricinus, fleas and mites, respectively, via blood meal. The problem of the spirochetes perfect adaptation to the host will be discussed.

Animals↗