bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel chitinase having a unique mode of action from Aspergillus fumigatus YJ‐407
Authors: Xia Guoqing , Jin Chunsheng , Zhou Ju , Yang Shoujun , Zhang Shuzheng , Jin Cheng
Published: March 2003

Chitinases are produced throughout the growth process of fungi and are thought to play important roles in morphogenesis. Aspergillus fumigatus, is an important pathogen of immunocompromised individuals in which it causes pneumonia and invasive disseminated disease with high mortality; it is also known to produce chitinase. We have induced an exceptionally stable extracellular chitinase in A. fumigatus YJ‐407, which could be isolated readily in a homogeneous form by using ammonium sulfate precipitation followed by DEAE‐cellulose chromatography and preparative PAGE. The molecular mass of this chitinase was estimated to be 46 000 by SDS/PAGE, and its isoelectric point was pH 5.6. The enzyme was most active at pH 5.0 and 60 °C, and was inhibited strongly by Hg2+, Pb2+, Ag+, Fe2+, Mn2+ and Zn2+. The enzyme was stable over a broad pH range 4–8 and below 45 °C. Tryptophan and carboxyl groups were found to be essential for the enzyme activity. The Michaelis constants for swollen chitin and chitosan were 1.12 mg·mL−1 and 1.84 mg·mL−1, respectively. The enzyme showed maximum activity towards glycol chitin and partially deacetylated chitosan, and lower activity towards colloidal chitin. Analysis of the hydrolysis product showed that the enzyme has both endo‐ and exo‐hydrolytic activities. In addition, a transglycosyl activity was also observed.
Recombinant human factor VIII‐specific affinity ligands selected from phage‐displayed combinatorial libraries of protein A
Authors: Nord Karin , Nord Olof , Uhlén Mathias , Kelley Brian , Ljungqvist Charlotta , Nygren Per‐Åke
Published: March 2003

Factor VIII‐specific affibodies were selected from phage displayed libraries constructed by combinatorial mutagenesis of an α helical bacterial receptor domain derived from staphylococcal protein A. Bead‐immobilized recombinant human factor VIII (rVIII) (80 and 90 kDa chains) protein was used during competitive biopannings in the presence of free 80‐kDa chain protein, resulting in the selection of several binders that showed dissociation constants (Kd) in the range 100–200 nmas determined by biosensor analyses. One variant (ZrVIII:3, 90‐kDa chain specific) was further characterized in small‐scale affinity chromatography experiments, and showed efficient and selective recovery of biologically active rVIII from Chinese hamster ovary cell supernatant‐derived feed stocks. The purity of the enriched rVIII was comparable with rVIII material purified by immunoaffinity chromatography using a 90‐kDa chain‐specific monoclonal antibody. Interestingly, epitope mapping showed that the monoclonal antibody and the affibody ligand competed for the same or at least overlapping epitopes on rVIII. In addition, the ZrVIII:3variant was produced by peptide synthesis with a C‐terminal cysteine to enable directed coupling to solid supports. This 59‐residue protein was analyzed by circular dichroism and showed a secondary structure content similar to that of the parental Z domain used as scaffold. In biosensor studies, the synthetic affibody was immobilized recruiting the C‐terminal cysteine residue, and demonstrated to bind both recombinantly produced and plasma‐derived factor VIII. From a secondary library, constructed by re‐randomization of relevant positions identified after alignment of the first‐generation variants, a panel of affinity‐improved second‐generation affibodies were selected of which one clone showed a dissociation constant (Kd) for rVIII of 5 nm. Several of these variants also showed higher apparent binding efficiencies towards rVIII when analyzed as immobilized ligands in biosensor experiments. Taken together, the results suggest that affibody ligands produced by bacterial or synthetic routes could be of interest as an alternative to monoclonal antibodies in purification processes or as diagnostic or monitoring tools.
Psychrophilic valine dehydrogenase of the antarctic psychrophile,  Cytophaga sp. KUC‐1
Authors: Oikawa Tadao , Yamanaka Kazuya , Kazuoka Takayuki , Kanzawa Noriyuki , Soda Kenji
Published: March 2003

We found the occurrence of valine dehydrogenase in the cell extract of a psychrophilic bacterium, Cytophaga sp. KUC‐1, isolated from Antarctic seawater and purified the enzyme to homogeneity. The molecular mass of the enzyme was determined to be ≈ 154 kDa by gel filtration and that of the subunit was 43 kDa by SDS/PAGE: the enzyme was a homotetramer. The enzyme required NAD+ as a coenzyme, and catalyzed the oxidative deamination of l‐valine, l‐isoleucine, l‐leucine and the reductive amination of α‐ketoisovalerate, α‐ketovalerate, α‐ketoisocaproate, and α‐ketocaproate. The reaction proceeds through an iso‐ordered bi–bi mechanism. The enzyme was highly susceptible to heat treatment and the half‐life at 45 °C was estimated to be 2.4 min. The kcat/Km (µ&mgr;−1·s−1) values for l‐valine and NAD+ at 20 °C were 27.48 and 421.6, respectively. The enzyme showed pro‐S stereospecificity for hydrogen transfer at the C4 position of the nicotinamide moiety of coenzyme. The gene encoding valine dehydrogenase was cloned into Escherichia coli (Novablue), and the primary structure of the enzyme was deduced on the basis of the nucleotide sequence of the gene encoding the enzyme. The enzyme contains 370 amino‐acid residues, and is highly homologous with S. coelicolor ValDH (identity, 46.7%) and S. fradiae ValDH (43.1%). Cytophaga sp. KUC‐1 ValDH contains much lower numbers of proline and arginine residues than those of other ValDHs. The changes probably lead to an increase in conformational flexibility of the Cytophaga enzyme molecule to enhance the catalytic activity at low temperatures.
Post‐translational modification of the S‐layer glycoprotein occurs following translocation across the plasma membrane of the haloarchaeon Haloferax volcanii
Authors: Eichler Jerry
Published: March 2003

The halophilic archaeon Haloferax volcanii is surrounded by a protein shell solely comprised of the S‐layer glycoprotein. While the gene sequence and glycosylation pattern of the protein and indeed the three‐dimensional structure of the surface layer formed by the protein have been described, little is known of the biosynthesis of the S‐layer glycoprotein. In the following, pulse‐chase radiolabeling and cell‐fractionation studies were employed to reveal that newly synthesized S‐layer glycoprotein undergoes a maturation step following translocation of the protein across the plasma membrane. The processing step, detected as an increase in the apparent molecular mass of the S‐layer glycoprotein, is unaffected by inhibition of protein synthesis and is apparently unrelated to glycosylation of the protein. Maturation requires the presence of magnesium ions, involved in membrane association of the S‐layer glycoprotein, and results in increased hydrophobicity of the protein as revealed by enhanced detergent binding. Thus, along with protein glycosylation, additional post‐translational modifications apparently occur on the external face of the haloarchaeal plasma membrane, the proposed topological homologue of the lumenal face of the eukaryal endoplasmic reticulum membrane.
A further clue to understanding the mobility of mitochondrial yeast cytochrome c
Authors: Barker Paul D. , Bertini Ivano , Del Conte Rebecca , Ferguson Stuart J. , Hajieva Parvana , Tomlinson Esther , Turano Paola , Viezzoli Maria Silvia
Published: March 2003

A new approach was developed to overproduce 15N‐enriched yeast iso‐1‐cytochrome c in the periplasm of Escherichia coli in order to perform a study of the motions in the ms–µs time scale on the oxidized and reduced forms through rotating frame 15N relaxation rates and proton/deuterium exchange studies. It is confirmed that the reduced protein is rather rigid whereas the oxidized species is more flexible. The regions of the protein that display increased internal mobility upon oxidation are easily identified by the number of residues experiencing conformational equilibria and by their exchange rates. These data complement the information already available in the literature and provide a comprehensive picture of the mobility in the protein. In particular, oxidation mobilizes the loop containing Met80 and, through specific contacts, affects the mobility of helix 3 and possibly of helix 5, and of a section of protein connecting the heme propionates to helix 2. The relevance of internal motions to molecular recognition and to the early steps of the unfolding process of the oxidized species is also discussed. In agreement with the reported data, subnanosecond mobility is found to be less informative than the ms–µs with respect to redox dependent properties.
Intrinsic versus extrinsic stabilization of enzymes
Authors: Fields Peter A. , Wahlstrand Benjamin D. , Somero George N.
Published: March 2003

We examined the effects of temperature and stabilizing solutes on A4‐lactate dehydrogenase (A4‐LDH) from warm‐ and cold‐adapted fishes, to determine how extrinsic stabilizers affect orthologs with different intrinsic stabilities. Conformational changes during substrate binding are rate‐limiting for A4‐LDH, thus stabilization due to intrinsic or extrinsic factors leads to decreased activity. A4‐LDH from a warm‐temperate goby (Gillichthys mirabilis), which has lower values for kcat and the Michaelis constant for pyruvate (

), was intrinsically more stable than the orthologs of the cold‐adapted Antarctic notothenioids Parachaenichthys charcoti and Chionodraco rastrospinosus, as shown by a higher apparent transition (‘melting’) temperature (Tm(APP)). We used four solutes, glycerol, sucrose, trimethylamine‐N‐oxide and poly(ethylene glycol) 8000, which stabilize proteins through different modes of preferential exclusion, to study temperature–solute interactions of the three orthologs. Changes in Tm(APP) were similar for all orthologs in each solute tested, but the catalytic rate of G. mirabilis A4‐LDH was decreased most by solutes and increased most by temperature. In contrast, the
values of the Antarctic orthologs were more affected than that of the goby by both solutes and temperature. We conclude that (a) preferential exclusion of solutes functions within the native state of A4‐LDH to favor conformational microstates with minimal surface area; (b) the varied effects of the different solutes on the kinetic properties are due to the interaction between this nonspecific stabilization and the differing intrinsic stabilities of the orthologs; (c) the catalytic rates of A4‐LDH orthologs are equally affected by stabilizing solutes, if measurements are made at physiologically appropriate temperatures; and (d) global stability and localized flexibility of these A4‐LDH orthologs may evolve independently.
Biosynthesis of (1→3)‐β‐d‐glucan (callose) by detergent extracts of a microsomal fraction from Arabidopsis thaliana
Authors: Him Joséphine L.K. , Pelosi Ludovic , Chanzy Henri , Putaux Jean‐Luc , Bulone Vincent
Published: March 2003

The aim of this work was to develop a biochemical approach to study (1→3)‐β‐d‐glucan (callose) biosynthesis using suspension cultures of Arabidopsis thaliana. Optimal conditions for in vitro synthesis of callose corresponded to an assay mixture containing 50 mm Mops buffer, pH 6.8, 1 mm UDP‐glucose, 8 mm Ca2+ and 20 mm cellobiose. The enzyme was Ca2+‐dependent, and addition of Mg2+ to the reaction mixture did not favour cellulose biosynthesis. Enzyme kinetics suggested the existence of positive homotropic cooperativity of (1→3)‐β‐d‐glucan synthase for the substrate UDP‐glucose, in agreement with the hypothesis that callose synthase consists of a multimeric complex containing several catalytic subunits. Detergents belonging to different families were tested for their ability to extract and preserve membrane‐bound (1→3)‐β‐d‐glucan synthase activity. Cryo‐transmission electron microscopy experiments showed that n‐octyl‐β‐d‐glucopyranoside allowed the production of micelle‐like structures, whereas vesicles were obtained with Chaps and Zwittergent 3‐12. The morphology and size of the (1→3)‐β‐d‐glucans synthesized in vitro by fractions obtained with different detergents were affected by the nature of the detergent tested. These data suggest that the general organization of the glucan synthase complexes and the properties of the in vitro products are influenced by the detergent used for protein extraction. The reaction products synthesized by different detergent extracts were characterized by infrared spectroscopy, methylation analysis, 13C‐NMR spectroscopy, electron microscopy and X‐ray diffraction. These products were identified as linear (1→3)‐β‐d‐glucans having a degree of polymerization higher than 100, a microfibrillar structure, and a low degree of crystallinity.
The H89 cAMP‐dependent protein kinase inhibitor blocks Plasmodium falciparum development in infected erythrocytes
Authors: Syin Chiang , Parzy Daniel , Traincard Francois , Boccaccio Irène , Joshi Manju B. , Lin David T. , Yang Xiao‐Ming , Assemat Karine , Doerig Christian , Langsley Gordon
Published: March 2003

In Plasmodium falciparum, the causative agent of human malaria, the catalytic subunit gene of cAMP‐dependent protein kinase (Pfpka‐c) exists as a single copy. Interestingly, its expression appears developmentally regulated, being at higher levels in the pathogenic asexualstages than in the sexual forms of parasite that areresponsible for transmission to the mosquito vector. Within asexual parasites, PfPKA activity can be readily detected in schizonts. Similar to endogenous PKA activityofnoninfected red blood cells, the parasite enzymecan be stimulated by cAMP and inhibited by protein kinase inhibitor.Importantly, exvivo treatment of infected erythrocytes with the classical PKA‐C inhibitor H89 leads to a block in parasite growth. This suggests that the PKA activities of infected red blood cells are essential for parasite multiplication. Finally, structural considerations suggest that drugs targeting the parasite, rather than the erythrocyte enzyme, might be developed that could help in the fight against malaria.
Purification, partial sequencing and characterization of an insect membrane dipeptidyl aminopeptidase that degrades the insect neuropeptide proctolin
Authors: Mazzocco Claire , Fukasawa Kayoko M. , Raymond Anne‐Aurélie , Puiroux Jacques
Published: March 2003

Two proctolin‐binding proteins solubilized from 1600 cockroach hindgut membranes were purified 1000‐fold using five chromatography steps. Twenty‐five micrograms of protein were recovered from the final size‐exclusion chromatography as a single peak eluting at 74 kDa, whereas two major bands at 80 and 76 kDa were identified after silver staining of electrophoresis gels. The fragments, sequenced by tandem mass spectrometry and the Edman method, revealed a high homology with rat liver dipeptidyl aminopeptidase (DPP) III and a significant homology between the cockroach‐purified proteins. From analysis of the Drosophila genome sequence database, it was possible to identify a putative DPP sharing high homology with the sequences obtained from the cockroach purified proteins and with the rat DPP III. Anti‐(rat liver DPP III) Ig reacted specifically with both cockroach‐purified proteins in Western blot analysis. The purified proteins removed the N‐terminal dipeptide from the insect myotropic neuropeptide proctolin (Arg‐Tyr‐Leu‐Pro‐Thr) with a Km value of 3.8 ± 1.1 µm. The specific DPP III inhibitor tynorphin prevented the degradation of proctolin by the purified insect DPP (IC50 = 0.68 µm). These results provide strong evidence that the cockroach‐purified proteins represent an insect membrane DPP, presumably present in Drosophila, and that it is closely related to vertebrate DPP III.
Dystrobrevin requires a dystrophin‐binding domain to function in Caenorhabditis elegans
Authors: Grisoni Karine , Gieseler Kathrin , Ségalat Laurent
Published: March 2003

Dystrobrevin is one of the intracellular components of the transmembrane dystrophin–glycoprotein complex (DGC). The functional role of this complex in normal and pathological situations has not yet been clearly established. Dystrobrevin disappears from the muscle membrane in Duchenne muscular dystrophy (DMD), which results from dystrophin mutations, as well as in limb girdle muscular dystrophies (LGMD), which results from mutations affecting other members of the DGC complex. These findings therefore suggest that dystrobrevin may play a pivotal role in the progression of these clinically related diseases. In this study, we used the Caenorhabditis elegans model to address the question of the relationship between dystrobrevin binding to dystrophin and dystrobrevin function. Deletions of the dystrobrevin protein were performed and the ability of␣the mutated forms to bind to dystrophin was tested both in vitro and in a two‐hybrid assay, as well as their ability to rescue dystrobrevin (dyb‐1) mutations in C. elegans. The deletions affecting the second helix of the Dyb‐1 coiled‐coil domain abolished the binding of dystrobrevin to dystrophin both in vitro and in the two‐hybrid assay. These deletions also abolished the rescuing activity of a functional transgene in vivo. These results are consistent with a model according to which dystrobrevin must bind to dystrophin to be able to function properly.
Communication of Stimulus Size and Shape in Alarm Calls of Gunnison’s Prairie Dogs, Cynomys gunnisoni
Authors: Ackers Steven H. , Slobodchikoff C. N.
Published: March 2003

Gunnison’s prairie dogs (Cynomys gunnisoni) emit multiple‐note alarm calls to terrestrial predators that vary in acoustic structure according to the eliciting stimulus. The characteristics of the predator that are salient with respect to alarm call variation, however, are poorly understood. Although the behavior of predators has been shown to influence alarm call production in other species of ground‐dwelling sciurids, the degree to which sciurid alarm calls describe physical characteristics of predators has not been addressed independently of the effects of variation in predator behavior. The effect of variation in the size and shape of the eliciting stimulus was studied by presenting silhouette models to a colony of prairie dogs and recording the alarm calls that were elicited. Discriminant function analysis on 7 variables measured from spectrograms revealed that the alarm calls differed with respect to silhouette. These results suggest that information with respect to stimulus size and shape is encoded in prairie dog alarm calls.
Time–Place Learning Based on Food but not on Predation Risk in a Fish, the Inanga (Galaxias maculatus)
Authors: Reebs Stephan G.
Published: March 2003

Time–place learning, or the ability to learn to be in different places at different times of day, is already known to occur in response to daily spatio‐temporal patterns of food availability. However, the ability to learn daily patterns of predation risk and move between areas at the right time of day in order to avoid predation has never been tested. This study asked whether inangas,Galaxias maculatus, are capable of time–place learning based on food availability only, predation risk only, or the antagonistic combination of food availability and predation risk. Shoals of five inangas were kept in aquaria partially divided into a right and left section. Every day they were exposed to a stimulus on one side in the morning and on the other side in the afternoon. Depending on the experiment, the stimulus could be two deliveries of food, two simulated heron strikes, or both of the above within the same hour. After 14 d the stimuli were not given and the position of the fish was noted in both the morning and the afternoon. The majority of the fish learned to switch sides at the correct daily time in order to get food, but they remained on the same side at both daily times in response to either predation risk alone or the combination of predation risk and food. It seems that the potential for time–place learning based on predation risk is less than that based on food, and that predation risk can even curtail the expression of time–place learning based on food. Fish may resort to other tactics, such as shoaling and reduced movement, in response to predation risk. Daily habitat shifts could still be present in nature and rooted in the avoidance of predation, but instead of being the direct result of learning they would be mostly innate.
Feeding Decisions by Steller’s Jays (Cyanocitta stelleri): The Utility of a Logistic Regression Model for Analyses of Where, What, and with Whom to Eat
Authors: Bekoff Marc , Allen Colin , Grant Michael C.
Published: March 2003

It is widely recognized that animal behavior is simultaneously affected by many variables. Both the study of interactions between these variables under naturalistic conditions and the proper statistical analysis of data derived from such studies remain particular problems for ethologists. In the present study we investigated choices by Steller’s jays (Cyanocitta stelleri) selecting between two feeding locations under a variety of conditions. A multifactor logistic regression analysis of our data showed that the jays’ behavior was simultaneously affected by several variables, including proximity of the feeding site to cover, food preferences, and the presence of conspecifics and other animals. We found that (1) jays strongly preferred an unoccupied feeder over one occupied by another jay or a sympatric mammal with the effect of squirrels being much greater than that of other jays, (2) contrary to our expectations, in the absence of a reason to prefer the other feeder, the jays generally selected the feeder that was further from nearest cover, and (3) the presence of sunflower seeds on one feeder but not on the other provided a reason to prefer the feeder offering sunflower seeds. The logistic regression analysis provided a more complete and integrated model of the birds’ behavior than more commonly used univariate methods. Our approach and results are also applicable to studies of other animals. While univariate analyses are useful in some instances, multifactor procedures reveal more details about the interactions of single factors and future experimental studies can take advantage of this additional knowledge.
Parasitism and Shoal Size in Juvenile Sticklebacks: Conflicting Selection Pressures from Different Ectoparasites?
Authors: Poulin Robert
Published: March 2003

In gregarious animals, group size correlates negatively with infection levels by some kinds of parasites and positively with infection by others. Conflicting selection pressures can be exerted simultaneously on a host species by different parasite species. Among stationary, mixed‐species shoals of juvenile threespine sticklebacks,Gasterosteus aculeatus, and blackspotted sticklebacks,Gasterosteus wheatlandi, shoal size correlated differently with levels of infection by two species of ectoparasites. Stickleback shoal size correlated positively with infection levels by the copepodThersitina gasterostei, which is transmitted among fish by short‐lived planktonic larvae. In contrast, infection levels by the highly mobile crustacean parasiteArgulus fundulidid not decrease as shoal size increased, as predicted from an earlier laboratory experiment. The species composition of the different stickleback shoals also had an influence on some aspects of infection by these two parasite species. The contrasting mode of transmission of the two parasites results in one parasite species having a higher transmission rate among fish within large shoals, whereas the success of the other parasite species is independent of fish shoal size. The two ectoparasites may thus exert different selection pressures on stickleback shoal sizes.
Regulation of Contact with Offspring by Domestic Sows: Temporal Patterns and Individual Variation
Authors: Pajor E. A. , Kramer D. L. , Fraser D.
Published: March 2003

We used a sow‐controlled housing system to examine temporal and individual variation in the tendency of sows to associate with young. During a 5‐week lactation, 22 sows and litters were housed in a pen where the sow could freely leave and re‐enter the piglets’ area by stepping over a barrier that the piglets could not cross. Despite this option, the sows remained with the piglets almost constantly during the 1st day after birth. Nineteen sows (‘leavers’) changed to spending most of their time away from the litter at some point in the lactation. The change was rapid, often within a single week, and occurred in week 2, 3, 4 or 5, depending on the individual. The time of rapid increase in time away was not related to characteristics of the sow or litter, including parity, litter size and sex ratio. Three sows (‘stayers’) did not increase their time away as lactation advanced, and rarely spent more than 15% of their day in the piglet‐free area. Nearly all sows showed a clear preference to defecate in the piglet‐free area. This study shows 1. that sows voluntarily reduce their contact with the young; 2. that the timing of this reduction varies greatly amongst sows for reasons that may relate to differences in maternal motivation, and 3. that sows do not abandon the litter if the young cannot follow. The clear preference that most sows developed for the piglet‐free area reinforces physiological evidence that constant confinement with older litters is aversive for many sows.
Endocrine and Behavioural Responses of Male Greylag Geese (Anser anser) to Pairbond Challenges during the Reproductive Season
Authors: Hirschenhauser Katharina , Möstl Erich , Wallner Bernard , Dittami John , Kotrschal Kurt
Published: March 2003

Although greylag geeseAnser anserestablish long‐term monogamous pairbonds, some of the existing pairs do split up (divorce) and new pairs are formed during the annual spring mating period. In this study, male greylag geese which were involved in the challenge of an existing pairbond (challenged males and challengers) were regarded as ‘natural experimental’ groups and compared with males in stable pairbonds (unchallenged males and male‐paired males, a common male strategy when the availability of females is low). In total, 37 males were investigated. The analysis included a description of the seasonal patterns of hormone levels, aggression and courtship. We tested whether hormone levels correlated with aggressive and courtship behaviours. Finally, we compared hormonal and behavioural patterns amongst the four groups. Immunoreactive testosterone (T) and corticosterone (B) equivalents were measured in faecal samples. Individual hormone levels were correlated with frequencies of agonistic male‐male interactions and with frequencies of male‐female courtship. During early mating and pre‐laying phases, T was at its seasonal maximum, which may have masked hormone‐behaviour correlations. During egg‐laying, at the onset of seasonally decreased T, agonistic male‐male interactions and the frequencies of courtship behaviour were significantly correlated with T. Unchallenged males had higher rates of agonistic interactions than any other males. However, unchallenged and challenged males tended to excrete T at higher levels than challengers. The high rates of being attacked and elevated levels of faecal B were indicative of the social conflict experienced by challengers. No hormonal differences were observed between heterosexually paired males and male‐paired males. In summary, pairbond status and situations of social conflict had a modulating effect on T and B; however, in this study, the two hormones seem to be affected independently of one another.
Crayfish (Cherax destructor) use Tactile Cues to Detect and Learn Topographical Changes in Their Environment
Authors: Basil Jennifer , Sandeman David
Published: March 2003

When placed in a rectangular aquarium (arena) containing no objects, blindfolded freshwater crayfish (Cherax destructor) explore by walking along the walls of the arena. Animals taken from their home tanks and placed in the arena for a 40‐min trial each day habituate and exhibit a reduction in their exploratory activity over 4 trials, despite their lack of continuous exposure to the arena. Dishabituation (i.e. an immediate increase in exploratory activity) occurs when animals were placed in the arena after the introduction of short partitions projecting at right angles from the walls. The dishabituation was interpreted as indicating that the animal can detect differences in the spatial configuration of the arena topography. Using dishabituation as a measure, we found that animals responded not only to the presence or absence of the partitions but also to changes in the position of the partitions. Animals with immobilized or lesioned second antennae no longer responded to configurational changes in the spatial arrangement of the partitions in the arena. We conclude that Cherax destructor relies upon the tactile input from its second antennae to detect topographical changes in the environment and that such topographical changes can be retained for at least 24 h. For an organism that forages in and defends a home territory on a daily basis, this seems to be an ecologically relevant time scale.
Determinants of Affiliative Interactions between Adult Males and Lactating Females in Pigtail Macaques (Macaca nemestrina nemestrina)
Authors: Maestripieri Dario
Published: March 2003

In some species of Cercopithecine primates, unrelated adult males and females maintain affiliative relationships (‘friendships’) that are apparently unrelated to mating or parental care. This study investigated the occurrence of friendships in a captive group of pigtail macaques, and some of their possible determinants. Study subjects were six adult males and 15 adult females with their newborn infants. Females were focally observed for 2 h every week during the first 12 wk of lactation. With the exception of the fourth‐ranking male, adult males showed little interest in initiating affiliative interactions with lactating females and their infants. Most episodes of contact and grooming were initiated by high‐ranking females and directed to the alpha male. Because female grooming was not generally reciprocated by the alpha male, it is likely that females benefited from associating with him in terms of agonistic support or protection. Genetic data on paternity determination indicated that the fourth‐ranking male, who displayed high levels of affiliation towards mother‐infant dyads, sired most of the infants born in the group in the year prior to this study. Thus, whereas females may be interested in associating with males to obtain their support, some males may affiliate with females as a consequence of their previous mating relationships with them or to increase the chances of future mating success. Taken together, however, the findings of this study provide little evidence that adult males and lactating females maintain strong reciprocal bonds that may qualify as friendships.
Female Choice, Female Reluctance to Mate and Sexual Selection on Body Size in the Dung Fly Sepsis cynipsea
Authors: Blanckenhorn Wolf U. , Mühlhäuser Claudia , Morf Cornelia , Reusch Thomas , Reuter Max
Published: March 2003

We investigated the mechanisms of sexual selection in the common dung fly Sepsis cynipsea and how these affect selection on body size at the population level. Because of the presumed costs associated with mating, we predicted that there would be a decrease in the general reluctance of females to mate with any particular male at higher male densities at the mating site, a fresh cow pat, resulting in indirect female choice and a decrease in the strength of sexual selection. In contrast, classical direct female choice and male‐male competition should result in increased selection intensities because more opportunities for choice and competition exist at higher densities. Female reluctance to mate and female assessment of males are expressed in prominent female behaviour to repel mates in several insect species, including S. cynipsea. Laboratory pair‐wise choice experiments showed that large males were more likely to obtain copulations, which also ensued more promptly, suggesting female assessment of male quality (direct female choice). There was a basic influence of male activity but little further effect of male scramble competition on the outcome of mating. Another laboratory experiment showed a decrease in female shaking duration per male, associated with an asymptote in the shaking duration per female, as male density and harassment increased, but did not show the increase in mating frequency predicted by the female reluctance hypothesis. A study estimating sexual selection differentials in the field showed that directional selection for larger males was present overall and was negatively related to seasonally mediated variation in male density. Our study suggests that direct female choice in combination with indirect female choice (due to an interaction of female reluctance to mate and male persistence) is most consistent with the behavioural and selection patterns observed in S. cynipsea, but male effects cannot be definitively excluded.
Individual Variation in Advertisement Calls of Territorial Male Green Frogs, Rana clamitans: Implications for Individual Discrimination
Authors: Bee Mark A. , Kozich Carol E. , Blackwell Kellee J. , Gerhardt H. Carl
Published: March 2003

Individuals of many territorial species discriminate between familiar territorial neighbors and unfamiliar strangers based on individual differences in acoustic signals. Many anuran amphibians are territorial and use primarily acoustic communication during social interactions, but evidence for acoustically mediated individual discrimination is available only for one species. As a first step in research designed to investigate individual discrimination in a second species of territorial frog, we examined patterns of within‐male and among‐male variability in 198 advertisement calls of 20 male green frogs, Rana clamitans. The aim was to determine which acoustic properties could be used by males to recognize their territorial neighbors and to estimate limits of reliability afforded by these properties for identifying different neighbors. All of the call properties that we examined exhibited significant inter‐individual variation. Discriminant function analyses assigned between 52% and 100% of calls to the correct individual, depending on sample size and the call properties included in the model. This suggests that there is sufficient among‐male variability to statistically identify individuals by their advertisement calls. The call properties of fundamental frequency and dominant frequency contributed the most towards discrimination among individuals. Based on their natural history and behavior and the results reported here, we suggest that male green frogs likely discriminate between strangers and adjacently territorial neighbors based on individual variation in advertisement calls.
Olfactory Communication and Neighbor Recognition in Giant Kangaroo Rats
Authors: Murdock Heather Gardner , Randall Jan A.
Published: March 2003

We hypothesized that olfactory communication facilitates neighbor recognition in the giant kangaroo rat, Dipodomys ingens, and is therefore influential in coordinating social interactions in this solitary, desert rodent. We tested whether (i) D. ingens can discriminate between odors of same‐ and opposite‐sex conspecifics; and (ii) the kangaroo rats exhibit scent preferences based on familiarity. In habituation‐discrimination tests, we found that both genders distinguish differences between the scent of individuals of the same‐ and opposite‐sex. In olfactory preference tests, both males and females spent significantly more time investigating the scent of their familiar cagemate than the scent of an unfamiliar conspecific. Giant kangaroo rats may be able to recognize familiar neighbors from olfactory cues, thus supporting a hypothesis of neighbor recognition. Neighbor recognition may be an important mechanism of social interactions in this endangered species.
Foraging Behaviour of Subordinate Great Tits (Parus major). Can Morphology Reduce the Cost of Subordination?
Authors: Barluenga M. , Moreno E. , Barbosa A.
Published: March 2003

This paper studies the magnitude of the behavioural shift, from forage standing to forage hanging, of subordinate great tits (Parus major) in two different social contexts: feeding solitarily vs. feeding with a dominant conspecific. The aim is to test the hypothesis that differences in morphological design provide subordinates with varying abilities to reduce the presumed costs of subordination. We find that different subordinate individuals change the foraging behaviour, occupying a different niche when an intra‐specific competitor is present. Morphology linked to sexual dimorphism, specifically body mass, is the factor responsible for the different magnitudes of change. Lighter subordinates can remain longer than heavier ones at the feeding patch without interrupting their foraging. Thereby, the former reduce the costs of being subordinate more than the latter. Among subordinates, females are lighter than males; they also spend more time feeding in the presence of a dominant conspecific than males do. No differences are found between age categories. We find no relationship between tarsus length and individual ecological plasticity. Our results support the idea that the ecological plasticity due to morphological differences is a mechanism that allows subordinate individuals to overcome costs associated with subordination.
Testing for Effects of UV‐B Radiation on Anti‐Predator Behavior in Amphibians: A Critique and Some Suggestions
Authors: Cummins Clive P.
Published: March 2003

In a recent paper, Kats et al. (2000) reported three experiments intended to test for effects of UV‐B radiation (hereafter, UV‐B) on predator‐avoidance behaviors in three amphibian species. They introduced their study in the context of concern about increasing penetration of solar UV‐B to ground level, owing to loss of stratospheric ozone, and its possible effects on amphibian populations. Kats et al. concluded from their results: `ultraviolet exposure may have important sub‐lethal effects in amphibians that could adversely effect (sic) their fitness'. As Kats et al. cited field studies that apparently demonstrated lethal effects of ambient levels of UV‐B on amphibians, their conclusion that sub‐lethal effects may occur is not obviously contentious. Furthermore, their experiments appear to be based on accepted methods. Nevertheless, I contend that the conclusions drawn by Kats et al. are not justified by the results they reported. Here, I discuss some problems with their study and suggest some possible improvements for future studies.
Identification of the Sex Responsible for Recognition and the Method of Ejection of Parasitic Eggs in Some Potential Common Cuckoo Hosts
Authors: Soler Manuel , Martín‐Vivaldi Manuel , Pérez‐Contreras Tomás
Published: March 2003

Egg rejection is the most common defence used by hosts against avian brood parasites and experimental studies have provided some of the best documented demonstrations of the coevolutionary process. However, the sex responsible for egg ejection and whether eggs are grasped or punctured are two essential questions that remain unanswered for most host species. In this paper, by filming the behaviour of individuals of three different species confronted with a foreign egg experimentally introduced into their nests, we first determine the relationship between recognition (when the birds aggressively pecked the experimental egg) and ejection. Secondly, we demonstrate that in the species where only the female incubates, only the female recognizes and ejects the model egg, whereas in the two species where both sexes incubate, both sexes eject the foreign egg. Finally, the large host species ejected the model egg by grasping it with the bill, whereas the two small species ejected it by puncturing it first. Furthermore, our data suggest that puncture ejection is more costly than grasping ejection considered both in terms of energetic and ejection costs.
The Neuroendocrine Function of Allosuckling
Authors: Roulin Alexandre
Published: March 2003

In mammals, females occasionally nurse offspring that are not their own. The function of allosuckling for foster females remains puzzling given that lactation is energetically costly and augments the risk of pathogen transmission. Current hypotheses suggest that allosuckling is not adaptive resulting from misguided parental behaviour, females reciprocate by nursing each other's offspring, females nurse preferentially related offspring for inclusive fitness benefits, females involved in allosuckling events evacuate extra milk or improve their maternal skills. These hypotheses received only little empirical evidence, and a recent review suggested that they are not mutually exclusive and do not exclude alternatives. Based on the established fact that teat stimulation by neonates leads to an elevated production of prolactin, I develop the hypothesis called ‘neuroendocrine function of allosuckling’ (NFA). The hypothesis postulates that the nursing of alien offspring allows females to increase and/or maintain prolactin concentration in the case own offspring do not stimulate their teats enough. This neurohormone enhances immunocompetence, the immunological quality and the quantity of milk whilst reducing female's fertility. The NFA suggests that via teat stimulation by the genetic offspring, and if necessary by foster ones, females can optimally adjust prolactin concentration, as both hypo‐ and hyper‐prolactinaemia entail physiological and immunological costs. The hypothesis does not only provide an explanation as to why females may nurse alien offspring but is also useful to understand the consequences of allosuckling. Indeed, even if mothers do not nurse alien offspring to control their prolactin production, allosuckling will alter the concentration of this crucial neurohormone.
Effect of three species of bacteria on damping‐off, root rot development, and ectomycorrhizal colonization of lodgepole pine and white spruce seedlings
Authors: Pedersen E. A. , Reddy M. S. , Chakravarty P.
Published: March 2003

Interactions between three species of bacteria (Burkholderia cepacia, Pseudomonas chlororaphis and Pseudomonas fluorescens), an ectomycorrhizal fungus (Paxillus involutus), and three root pathogenic fungi (Fusarium moniliforme, Fusarium oxysporum and Rhizoctonia solani) were studied. Burkholderia cepacia significantly reduced the in vitro mycelial growth of P. involutus, whereas, B. cepacia, Ps. chlororaphis, Ps. fluorescens and P. involutus reduced the mycelial growth of F. moniliforme, F. oxysporum and R. solani. Culture filtrates of B. cepacia, Ps. chlororaphis, Ps. fluorescens and P. involutus reduced conidial germination and increased the formation of chlamydospores of F. moniliforme and F. oxysporum. Burkholderia cepacia also reduced the formation of ectomycorrhizal short roots by P. involutus on lodgepole pine (Pinus contorta) and white spruce (Picea glauca) seedlings 2 months after inoculation. However, no significance difference in mycorrhizal short roots was observed after 4 months. The fungicide Anchor (a mixture of carboxine and thiram) significantly reduced root rot severity and increased the survival of lodgepole pine seedlings grown in a growth mix infested with F. moniliforme, F. oxysporum and R. solani. Control of the diseases of white spruce caused by these pathogens was not as successful. Treatment of seeds with either B. cepacia or P. involutus alone significantly increased the survival of seedlings grown in a mix that was inoculated with F. moniliforme and reduced the root rot severity caused by F. moniliforme and F. oxysporum, but not R. solani. Higher seedling survival and lower root rot severity were observed when conifer seeds were concomitantly inoculated with one of the bacterial species, P. involutus and Anchor.
Heterobasidion annosum group S identified in north‐eastern China
Authors: Dai Y‐C. , Korhonen K.
Published: March 2003

Samples of Heterobasidion annosum were collected in two stands of mixed forest in Changbaishan Nature Reserve in north‐eastern China. Pure cultures were isolated from 15 specimens growing on Abies, Picea, Pinus and Populus. Mating tests showed that all these collections belong to the S inter‐sterility group. The compatibility of Chinese homokaryons with S homokaryons from Europe was 100%. Clamp connections appeared almost equally in both strains of each pairing, and no distinct demarcation line formed in the pairings. The mating frequency of Chinese isolates with the European F group was also high, approximately 94%. These matings, however, were usually unilateral and a more or less distinct demarcation line was present in most of the pairings. The Chinese isolates were completely intersterile with the European P group. The S group of H. annosum in north‐eastern China appears to have similar morphology and ecology as in Europe. It is common on Abies and Picea, but is not a serious pathogen in the pristine forests of north‐eastern China.
Effects of benomyl and captan on growth and mycorrhizal colonization of Sitka‐spruce (Picea sitchensis) and ash (Fraxinus excelsior) in Irish nursery soil
Authors: O'neill J. J. M. , Mitchell D. T.
Published: March 2003

The effects of two fungicides (benomyl and captan ‐ at recommended doses and up to three soil drenches) on root development and mycorrhizal colonization of Sitka‐spruce (Picea sitchensis) and ash (Fraxinus excelsior) were examined after 20 weeks growth, under environmentally controlled conditions, in soil from an Irish tree nursery. Although four mycorrhizal types have been found on Sitka‐spruce at the nursery, only one ectomycorrhizal type (Piceirhiza horti‐inflata) was identified on the short roots in this study. An inoculant (Vaminoc: MicroBio Ltd, Hemel Hempstead, UK) was used to inoculate ash and 20‐week‐old seedlings had a higher arbuscular mycorrhizal (AM) colonization in comparison with uninoculated controls. Multiple applications (2–3) of benomyl reduced the length of root and shoot and shoot dry mass of Sitka‐spruce, whereas in ash, it only depressed root length. Benomyl decreased the numbers of ectomycorrhizas of Sitka‐spruce and arbuscular mycorrhizal colonization of Vaminoc‐inoculated ash. A single application of captan stimulated root length and ectomycorrhizal colonization of Sitka‐spruce and root dry mass in ash compared with uninoculated controls. Applications of captan reduced arbuscular mycorrhizal colonization of Vaminoc‐inoculated ash to levels near to those of uninoculated controls. Of the two fungicides used, benomyl had the most deleterious effect on root length and mycorrhizal colonization of Sitka‐spruce and ash.
First report of bacterial wilt caused by Ralstonia solanacearum on eucalypts in South Africa
Authors: Coutinho T. A. , Roux J. , Riedel K‐H. , Terblanche J. , Wingfield M. J.
Published: March 2003

Ralstonia solanacearum, the causal agent of bacterial wilt, has one of the widest host ranges of all phytopathogenic bacteria. This pathogen was first reported on Eucalyptus spp. in the late 1980s in Brazil. Since then, there have been reports of its occurrence on this host in Australia, China and Venezuela. Early in 1997, an 18‐month‐old clonally propagated Eucalyptus grandis × Eucalyptus camaldulensis (GC) hybrid in Zululand, KwaZulu/Natal, showed signs of wilting. The vascular tissue of infected trees was dicoloured and bacterial exudation was produced from cut surfaces. The bacterium was consistently isolated from diseased tissue, purified and identified as R. solanacearum biovar 3 race 1, using the BioLog bacterial identification system. Inoculation trials were conducted on three E. grandis × E. camaldulensis clones (GC515, GC550 and GC505). Clone GC550 displayed wilting after 3 days and all cuttings subsequently died. Clones GC515 and GC505 appeared to be less susceptible with cuttings not showing signs of disease until 7 days after inoculation. After 14 days, 90 and 80%, respectively, of cuttings of these two clones had died. This is the first report of bacterial wilt on Eucalyptus in South Africa.