Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Preferences for anuran calls in hematophagous corethrellids (Diptera : Corethrellidae) from Southern Brazil
Ambrozio-Assis, André ; Cortês Lopes, Benedito ; Amaral, André P. ; Pinho, Luiz C. ; Peeters, Edwin T.H.M. ; Neckel-Oliveira, Selvino - \ 2018
Austral Entomology (2018). - ISSN 2052-174X
Atlantic forest - frog-biting midges - frogs - parasitism - phonotaxis

Corethrellids are hematophagous flies that locate their frog hosts by using their calls as an auditory cue. The attractiveness of frog calls to these insects has been associated with the complexity of the vocalisation or an evolutionary relationship between the fly and frog species. We investigated the possible preferences of a local Corethrella fauna for the calls of six anurans, three species of the genus Boana (Hylidae) and three Physalaemus (Leptodactylidae) species in the Atlantic Rainforest of southern Brazil. We recorded loops of the natural advertisement calls of the different frog host species, which we broadcast from acoustic traps consisting of modified CDC (Center for Disease Control) traps fitted with a speaker under the collecting system, but without a source of light. Nine species of hematophagous flies were captured during 360 h of trapping. Three of the species captured were new to Brazil, and two could not be identified and may represent new taxa. Two corethrellid species contributed 75% of the individuals captured and were present in all the acoustic traps, while three species were attracted to only one trap. The median richness and abundance of corethrellids varied significantly in relation to the different calls broadcast by the traps. These differences in the abundance and species richness of Corethrella in the traps indicate that the frog calls vary in their attractiveness to the hematophagous flies. A model-based analysis using mvabund also indicated that the frog species and genera that produced the calls used in an acoustic trap were a significant factor determining the composition of the Corethrella assemblages captured in that trap. The variation found in the Corethrella communities of southern Brazil may be explained not only by the acoustic traits of frog vocalisations but also by differences in the morphological and ecological characteristics of the frog species.

Antimicrobial peptides with therapeutic potential from skin secretions of polyploid frogs of the Pipidae family
Mechkarska, M.P.M. - \ 2013
University. Promotor(en): Jerry Wells. - [S.l.] : s.n. - ISBN 9789461735508 - 224
kikkers - pipidae - secreties - antimicrobiële peptiden - gastheer-pathogeen interacties - frogs - secretions - antimicrobial peptides - host pathogen interactions

The emergence of pathogenic bacteria and fungi resistant to commonly used antibiotics poses a serious threat to public health and necessitates novel treatment approaches in order to control infections. Antimicrobial peptides (AMPs) are one of the central components of the system of innate immunity and due to their non-specific and highly destructive mechanism of killing, pathogens will develop resistance at lower rates than conventional antibiotics.Skin secretions of frogs from the family Pipidae are a rich source of AMPs which show potential for development into therapeutic agents.

Until recently, the only representatives of the Pipidae family frogs from which dermal AMPs had been identified were the diploid frog Silurana tropicalis, the tetraploid frog Xenopus laevis and the octoploid frog Xenopus amieti. Therefore, this program of research was undertaken with the aim to isolate, purify and characterize AMPs with therapeutic potential from skin secretions of other polyploid species of African clawed frogs of the Pipidae family. Emphasis is given to the application of the AMPs as markers to elucidate the taxonomic relationships and evolutionary history of the frogs. The study also investigates the effects which polyploidization and interspecies hybridization have had on the multiplicity of AMPs in frog skin secretions.

Chapter 2 and Chapter 3 present data from the peptidomic analysis of norepinephrine-stimulated skin secretions of two well-characterized and closely related tetraploid Xenopus species – X. borealis and
X. clivii. Multiple peptides with varying degrees of antimicrobial activity were isolated. Structural characterization demonstrated that they were orthologous to magainins, peptide glycine-leucine-amide (PGLa), caerulein-precursor fragments (CPFs) and xenopsin-precursor fragments (XPFs), previously isolated from S. tropicalis, X. laevis and X. amieti. CPF-B1 and CPF-C1 were the most abundant AMPs in the skin secretions of X. borealis and X. clivii respectively. CPF-B1 (GLGSLLGKAFKIGLKTVGKMMGGAPREQ) was active against clinical isolates of the hospital-associated pathogens, methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDRAB) with MIC = 5 µM and showed low hemolytic activity against human erythrocytes (HC50 >200 µM). CPF-C1 (GFGSLLGKALRLGANVL.NH2) also showed potent activity against a range of Gram-negative bacteria. CPF peptides, therefore, represent promising candidates for development into therapeutic agents for use against these emerging antibiotic-resistant pathogens.

The genera Silurana and Xenopus are united in the subfamily Xenopodinae and have a complex evolutionary history. Chapter 4 includes data from the peptidomic analysis of skin secretions from an incompletely characterized tetraploid species termed “S. new tetraploid 1”with chromosome number 2n=40 and the octoploid species X. andrei (2n=72). The species represent model systems in which to study of the fate of duplicated AMP genes following putative allopolyploidization events. Multiple peptides belonging to the PGLa, XPF, and CPF familes were identified. The primary structures of the AMPs from X. andrei indicate aclose phylogenetic relationship between this species and the previously studied X. amieti. Three CPF peptides from “S. new tetraploid 1” showed potent, broad-spectrum antimicrobial activity and are present in high abundance. In contrast, only a single CPF peptide was isolated in low yield from the X. andrei secretions. There is no increase in the multiplicity of the AMPs in skin secretions of “S. new tetraploid 1”and the octoploid X. andrei when compared to the diploid
S. tropicalis (2n=20) and the tetraploid X. laevis (2n=36). It is concluded that nonfunctionalization (gene silencing) has been the most common fate of duplicated AMP genes following polyploidization in the Silurana and Xenopus lineages.

AMPs constitute a characteristic ‘‘fingerprint’’ of a particular frog species that may be used for an unequivocal taxonomic classification. Two populations of the tetraploid X. muelleri, occupying separate non-contiguous ranges in east and west Africa, are studied in Chapter 5. Their taxonomic relationship is unclear and it has been proposed that the western population represents a separate species referred to as
X. muelleri West while the eastern population retains the original name X. muelleri. A comparison of the primary sequences of AMPs in skin secretions reveals that no orthologous peptide from the two populations of X. muelleri has the same amino acid sequence. Additionally, the X. muelleri secretions, like those from X. clivii, did not contain a PGLa peptide whereas the X. muelleri West secretions contained two members of this family. The data indicate that X. muelleri West is more closely related to X. borealis than to X. muelleri and so provide strong support for the proposal that X. muelleri and
X. muelleri West should be described as separate species.

In contrast to species in the subfamily Xenopodinae, frogs from the subfamily Pipinae have not been investigated as a source of AMPs. The AMP profile in skin secretions from Hymenochirus boettgeri as a representative of genus Hymenochirus (subfamily Pipinae) is described in Chapter 6. A novel family of five structurally-related peptides, designated as hymenochirins, was identified. Hymenochirin-1B (IKLSPETKDNLKKVLKGAIKGAIAV AKMV.NH2) is C-terminally α-amidated whereas hymenochirins-2B - 5B have the general structure XKIPX2VKDTLKKVAKG X2SX2 AGAX3.COOH. The most abundant peptide in the secretions was hymenochirin-3B (IKIPAVVKDTLKKVAKGVLSAVAGALTQ). Synthetic replicates of hymenochirin-1B - 4B possess broad-spectrum antimicrobial activity and relatively weak hemolytic activity and so represent potential candidates for development into therapeutically valuable agents against drug-resistant pathogens. The hymenochirins show very low structural similarity with the antimicrobial peptides isolated from skin secretions of S. tropicalis and X. laevis consistent with the proposed ancient divergence of the Pipinae and Xenopodinae.

The F1 hybrid frogs X. laevis x X. muelleri represent a model of interspecies hybridization in the Pipidae family that does not result in an increase in ploidy. They arestudied in Chapter 7 and the data obtained provide an insight into the mode of inheritance of AMPs. A total of 18 different AMPs were isolated from skin secretions of the female hybrids. In addition to the complement of AMPs from the parent species, three previously undescribed peptides (magainin-LM1, PGLa-LM1, and CPF-LM1) were purified from the secretions of the hybrid frogs that were not detected in secretions from either X. laevis or X. muelleri. Magainin-LM1 differs from magainin 2 from X. laevis by a single amino acid substitution (Gly13 ®Ala) but PGLa-LM1 and CPF-LM1 differ appreciably in structure from orthologs in the parent species. CPF-LM1 shows potent, broad-spectrum antimicrobial activity and is hemolytic. The data indicate that hybridization increases the multiplicity of host-defense peptides in skin secretions. As the female F1 hybrids are fertile, hybridization may represent an adaptive strategy among Xenopus species to increase protection against pathogenic microorganisms in the environment.

The thesis is completed by a general discussion in Chapter 8 of theresults and conclusions in Chapters 2-7. The potential of AMPs from skin secretions of frogs belonging to the Pipidae family is reviewed from three different aspects: promising candidates for development into therapeutic valuable anti-infective agents; reliable taxonomic and phylogenetic markers; and tools to study the fate of duplicated genes in Xenopus and Silurana. The interspecies Xenopus hybrids are proposed as a suitable model to perform future studies on the mode of inheritance of skin AMPs.

Gratis openluchtconcerten te beluisteren
Werkman, E. - \ 2010
Nature Today 2010 (2010)30-05.
anura - kikkers - soorten - voortplanting - frogs - species - reproduction
Wie nu op een zonnige dag langs sloten en poelen wandelt of fietst kan niet om de markante groene kikkerkoren heen. In grote groepen lokken de mannetjes al roepend de vrouwtjes naar zich toe. Groene kikkers zijn altijd wat later met paren dan de andere kikkersoorten. De piek van de paartijd valt rond eind mei, maar het paren gaat nog door tot ongeveer half juli.
Base composition, selection, and phylogenetic significance of indels in the recombination activating gene-1 in vertebrates
Chiari, Y. ; Meijden, A. van der; Madsen, O. ; Vences, M. ; Meyer, A. - \ 2009
Frontiers in Zoology 6 (2009). - ISSN 1742-9994 - 15 p.
nuclear rag-1 gene - v(d)j recombination - mitochondrial-dna - evolution - sequences - diversification - patterns - frogs - amphibians - inference
Background: The Recombination Activating Proteins, RAG1 and RAG2, play a crucial role in the immune response in vertebrates. Among the nuclear markers currently used for phylogenetic purposes, Rag1 has especially enjoyed enormous popularity, since it successfully contributed to elucidating the relationships among and within a large variety of vertebrate lineages. We here report on a comparative investigation of the genetic variation, base composition, presence of indels, and selection in Rag1 in different vertebrate lineages (Actinopterygii, Amphibia, Aves, Chondrichthyes, Crocodylia, Lepidosauria, Mammalia, and Testudines) through the analysis of 582 sequences obtained from Genbank. We also analyze possible differences between distinct parts of the gene with different type of protein functions. Results: In the vertebrate lineages studied, Rag1 is over 3 kb long. We observed a high level of heterogeneity in base composition at the 3(rd) codon position in some of the studied vertebrate lineages and in some specific taxa. This result is also paralleled by taxonomic differences in the GC content at the same codon position. Moreover, positive selection occurs at some sites in Aves, Lepidosauria and Testudines. Indels, which are often used as phylogenetic characters, are more informative across vertebrates in the 5' than in the 3'-end of the gene. When the entire gene is considered, the use of indels as phylogenetic character only recovers one major vertebrate clade, the Actinopterygii. However, in numerous cases insertions or deletions are specific to a monophyletic group. Conclusions: Rag1 is a phylogenetic marker of undoubted quality. Our study points to the need of carrying out a preliminary investigation on the base composition and the possible existence of sites under selection of this gene within the groups studied to avoid misleading resolution. The gene shows highly heterogeneous base composition, which affects some taxa in particular and contains sites under positive selection in some vertebrate lineages in the 5'-end. The first part of the gene (5'-end) is more variable than the second (3'-end), and less affected by a heterogeneous base composition. However, in some vertebrate lineages the 5'-end of the gene is not yet widely used for phylogenetic studies
Effects of temporary food limitation on development and mortality of Macoma balthica larvae
Bos, O.G. ; Philippart, C.J.M. ; Meer, J. - \ 2007
Marine Ecology Progress Series 330 (2007). - ISSN 0171-8630 - p. 155 - 162.
dutch wadden sea - metamorphosis - recruitment - population - temperature - responses - models - growth - frogs - size
Long-term observations (1973 to 2001) of populations of the intertidal bivalve Macoma balthica, in the western Wadden Sea, have suggested that larval mortality is strongly density-dependent. In addition, density-independent factors may affect larval mortality. One possible source for such an effect is food limitation. In laboratory experiments, M. balthica larvae were reared under food limiting conditions, both quantitatively (high or low food level) and temporally (starvation during the first, second or third week). The results indicated that larvae offered high food levels grew significantly faster (6.9 µm d¿1), and metamorphosed earlier (16.5 d) and at greater length (264 µm) than larvae subjected to low food level (4.4 µm d¿1, 19.3 d and 244 µm, respectively). For both food levels, starvation in the first week resulted in a late metamorphosis at a large size, starvation in the second week resulted in an early metamorphosis at a small size, and starvation in the third week yielded intermediate results. Larval mortality was always lower in the low food condition, but the timing of starvation had no impact on mortality. This suggests that larvae, in vivo, do not die directly from food limitation alone. The results are discussed with reference to models of metamorphosis.
De kleine groene kikker in Buitenvaart. Beoordeling van de effecten van de aanleg van bedrijventerrein Buitenvaart 2 in de gemeente Hoogeveen op het duurzaam voortbestaan van de Kleine groene kikker (Rana lessonae) en mogelijkheden voor compensatie
Blitterswijk, H. van; Stumpel, A.H.P. ; Vliet, C.J.M. van - \ 2003
Wageningen : Alterra (Alterra-rapport 765) - 25
rana - kikkers - industrieterreinen - milieueffect - milieuwetgeving - vergoeding - natuurbescherming - nederland - frogs - industrial sites - environmental impact - environmental legislation - compensation - nature conservation - netherlands
Mede in het licht van de Flora- en faunawet worden de effecten beoordeeld van de geplande aanleg van een bedrijventerrein in de gemeente Hoogeveen op de populaties Kleine groene kikker (Rana lessonae). Tevens worden maatregelen genoemd ter compensatie en mitigatie van deze effecten.
Zeven kikkers in een boerensloot : ontruiming van Buitenvaart 1 te Hoogeveen: kikkers moeten wijken voor bedrijventerrein
Stumpel, A.H.P. ; Blitterswijk, H. van - \ 2002
Wageningen : Alterra - 19
amphibia - kikkers - bedreigde soorten - wildbescherming - nederland - drenthe - amfibieën - aquatische ecologie - fauna - herpetologie - Hoogeveen - frogs - endangered species - wildlife conservation - netherlands
Bezetting en kolonisatie van poelen door kamsalamander en bruine kikker in Twente
Sluis, T. van der; Bugter, R. - \ 2000
De Levende Natuur 101 (2000)4. - ISSN 0024-1520 - p. 107 - 111.
plassen - biotopen - habitats - aquatisch milieu - hydrobiologie - populatiedichtheid - populatiedynamica - populatie-ecologie - kolonisatie - dispersie - amphibia - kikkers - rana temporaria - inventarisaties - monitoring - natuurbescherming - salamanders - aquatische ecosystemen - populatiebiologie - overijssel - twente - ponds - biotopes - aquatic environment - hydrobiology - population density - population dynamics - population ecology - colonization - dispersion - frogs - inventories - nature conservation - aquatic ecosystems - population biology
Effects of road density; a case study of the moor frog.
Vos, C.C. - \ 1997
In: Habitat fragmentation & infrastructure : proceedings of the international conference "Habitat fragmentation, infrastructure and the role of ecological engineering", 17 - 21 September 1995, Maastricht - The Hague, The Netherlands. - - p. 93 - 97.
verkeer - verkeerspatronen - dichtheid - capaciteit - tellen - onderzoek - dieren - territorium - habitats - milieu - anura - kikkers - padden - multivariate analyse - correlatieanalyse - regressieanalyse - nadelige gevolgen - milieueffect - menselijke activiteit - traffic - traffic patterns - density - capacity - counting - research - animals - territory - environment - frogs - toads - multivariate analysis - correlation analysis - regression analysis - adverse effects - environmental impact - human activity
Versnippering
Effecten van wegen op het voorkomen van de heikikker in Zuidwest-Drenthe
Vos, C.C. ; Chardon, J.P. - \ 1996
Delft : Rijkswaterstaat, Dienst Weg- en Waterbouwkunde - 42
verspreiding - ranidae - kikkers - dieren - territorium - habitats - milieu - wegen - nadelige gevolgen - milieueffect - menselijke activiteit - nederland - diergemeenschappen - drenthe - habitatfragmentatie - dispersal - frogs - animals - territory - environment - roads - adverse effects - environmental impact - human activity - netherlands - animal communities - habitat fragmentation
Naar meetnetten voor reptielen en amfibieen
Stumpel, A.H.P. ; Siepel, H. - \ 1993
Wageningen : IBN (IBN - rapport 033)
amphibia - anura - caudata - kikkers - herpetologie - inventarisaties - nederland - reptielen - padden - veldwerk - observatie - frogs - herpetology - inventories - netherlands - reptiles - toads - field work - observation
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