Vocal discrimination of potential mates by female giant pandas (Ailuropoda melanoleuca)

In the current study, we used male giant panda (Ailuropoda melanoleuca) bleats in a habituation–discrimination paradigm to determine whether females discriminate between the vocalizations of different males. We found that females habituated to the bleats of a specific male showed a significant dishabituation when they were presented with bleats from a novel male. Further playbacks, in which we standardized the mean fundamental frequency (pitch) and amplitude modulation of male bleats, indicated that amplitude modulation is the key feature that females attend to when discriminating between male callers. Our results show that female giant pandas can discriminate between the vocalizations of potential mates and provide a platform for further studies investigating the functional role of caller identity in giant panda sexual communication.     

The role of roots in sex expression in hemp plants

When the shoots of young hemp (Cannabis sativa L.) plants were cut off the roots, cultured as cuttings, and regenerating (adventitious) roots were removed as soon as appearing, ca. 80–90% of the plants became male (had staminate flowers) whereas if the roots were allowed to develop a similar percentage became female (pistillate flowers). Treatment of de-rooted cuttings with 6-benzylaminopurine (15 mg/l) restored the percent of female plants to ca. 80. It is suggested that the root system plays an essential role in sex expression in hemp and that this role is related to cytokinin synthesis in the root.     

Reduction of the response to sex pheromone in the oriental fruit moth,Grapholita molesta (Lepidoptera: Tortricidae) following successive pheromonal exposures

The effects of prior pheromonal experience upon the pheromone- mediated upwind flight response was examined in the oriental fruit moth, Grapholita molesta(Busck) (Lepidoptera: Tortricidae). Adult male G. molestawere subjected to a parallel series of staggered and repeated pheromonal exposures in a sustained-flight wind tunnel. Levels of response to pheromone in male G. molestasignificantly decreased in a (a) rectilinear function with increased ages of individuals, (b) logarithmic function of successive trials, and (c) steeper logarithmic function of successive trials with increased dosage of sex pheromone. The baseline levels of responding were not affected by either the (a) dosage of sex pheromone, (b) posteclosion ages of individuals for their initial exposures once the main effect of age itself was estimated, (c) elapsed time in hours between trials, or (d) discrete days of testing as integral intervals, disregarding hours within days.     

Stability of the cytokinin requirement in Paul's scarlet rose cells in culture

Summary Cells ofRosa sp. cv Paul's scarlet have been reported to require cytokinin for growth in suspension culture. This report was verified in the present study. However, a rose cell line that was maintained for 2 yr in suspension culture by routine subculturing developed the capacity to grow without exogenous cytokinin. The stability of the cytokinin requirement and the basis for this altered response to cytokinin was investigated. The parental cell line, which has been maintained independently on agar-solidified medium, was subcloned and the cytokinin dependence of the subclones was determined. The subclones were found to exhibit a continuous spectrum of responses, ranging from a high degree of cytokinin dependence for growth to rapid growth upon the initial transfer to cytokinin-deficient medium. The average growth constant (K=1n W/Wo; Wo=initial fresh weight,W=fresh weight after growth for the stated time interval) of 30 subclones grown on medium containing 0.5 μM zeatin was 3.1, with a range of 1.1 to 4.0. The average growth constant of the same subclones when grown on medium lacking a cytokinin was 1.5, with a range of 0 to 3.9. By comparison, the parental cell line exhibited growth constants of 3.5 in the presence of 0.5 μM zeatin and 1.6 in the absence of exogenous cytokinin. Although the growth of some of the subclones after transfer to cytokinin-deficient medium suggested that they were cytokinin autotrophs, this was not the case because none of them grew after a second transfer to medium lacking cytokinin. Culture in medium containing cytokinin conferred upon the cells the capacity for a limited amount of growth after subsequent transfer to medium lacking cytokinin. The extent of this cytokinin-induced growth potential varied from subclone to subclone. Efforts to determine the frequency with which cytokinin autotrophs appeared in a subclone that required cytokinin suggested that it is a rare event and that the cytokinin requirement is a fairly stable phenotypic characteristic of these cells. This research was supported by Grant PCM 7722398 from the National Science Foundation.     

Response of Wolves to Experimental Disturbance at Homesites

ABSTRACT Events during the denning period (parturition to first autumn) often determine the reproductive success of wolves (Canis lupus). Consequently, there is concern about the potential adverse effects of human-caused disturbance at wolf den and rendezvous sites (homesites), but relatively little information on this subject is available. We conducted standardized experimental disturbance treatments at 12 unique wolf homesites in the Northwest Territories, Canada, during summers 2002 and 2003. The treatment consisted of an intruder approaching a homesite once per day for 3 consecutive days and recording behavioral responses, response distance, and response intensity of wolves. We counted pups and estimated their ages prior to the initial treatment at each site. Adult wolves moved pups at 3 of 6 treated homesites in each year. The amount and type of known human activity within a pack's home range did not influence whether adults moved pups in response to the treatment. The response intensity of wolves to the treatment was inversely related to the amount of human activity near a homesite. There was no relationship between the distance at which wolves responded to the intruder and the amount or type of human activity. There was a positive relationship between increasing age of pups and their relocation in response to the treatment. Reproductive success was not influenced by the treatment or by the amount and type of human activity. Treated sites were used by wolves the following year in the same proportion as untreated sites. It appears that pups are most vulnerable early in the year when less mobile; therefore, managers should consider age of pups before human activity at or near wolf homesites occurs.     

Specificity and multiplicity in the recognition of individuals: implications for the evolution of social behaviour

Recognition of conspecifics occurs when individuals classify sets of conspecifics based on sensory input from them and associate these sets with different responses. Classification of conspecifics can vary in specificity (the number of individuals included in a set) and multiplicity (the number of sets differentiated). In other words, the information transmitted varies in complexity. Although recognition of conspecifics has been reported in a wide variety of organisms, few reports have addressed the specificity or multiplicity of this capability. This review discusses examples of these patterns, the mechanisms that can produce them, and the evolution of these mechanisms. Individual recognition is one end of a spectrum of specificity, and binary classification of conspecifics is one end of a spectrum of multiplicity. In some cases, recognition requires no more than simple forms of learning, such as habituation, yet results in individually specific recognition. In other cases, recognition of individuals involves complex associations of multiple cues with multiple previous experiences in particular contexts. Complex mechanisms for recognition are expected to evolve only when simpler mechanisms do not provide sufficient specificity and multiplicity to obtain the available advantages. In particular, the evolution of cooperation and deception is always promoted by specificity and multiplicity in recognition. Nevertheless, there is only one demonstration that recognition of specific individuals contributes to cooperation in animals other than primates. Human capacities for individual recognition probably have a central role in the evolution of complex forms of human cooperation and deception. Although relatively little studied, this capability probably rivals cognitive abilities for language.     

Habituation of caddies Chaetopteryx villosa Fabr. Larvae to vibrational stimulus and effect of piracetam on it

Habituation to a vibrational stimulus was studied in intact caddies Chaetopteryx villosa Fabr. of the last age before pupation and of the larvae placed for 72 h into piracetam solution (100 mg/l). The vibrational stimulus was shown to produce a passive-defensive reaction: the caddies were pulled into the house and stood still. In the course of the experiment the time of stay in the house decreased statistically significantly in both groups. Piracetam did not affect the defensive reaction at the initial moment of the first vibrational stimulus, so both in the experimental and in the control groups the number of contracted larvae was equal and all of them remained in the house for the first seconds of vibration. However, the compound increased the number of larvae that did not respond to the next vibrational stimulus and decreased the number of larvae that remain in the house throughout all 10 s of action by accelerating on the whole the habituation. Hence, on this model, the mnemotropic effect of the standard nootrope has been realized, which earlier was established by other methods in mammals, the lower vertebrates, and the higher invertebrates. This indicates that this model also is perspective for comparative studies of effect of nootropic substances on the higher nervous activity.     

Growth regulators,Rhizobium and nodulation in peas

The cytokinin content of roots and nodules of pea and the culture supernatants from two strains of Rhizobium leguminosarum has been examined. Roots, nodules and wild-type Rhizobium culture medium contained very little cytokinin as indicated by bioassay. Chemical ionisation gas chromatography-mass spectrometric analysis of the isopentenyladenine content of the culture medium from the Rhizobium strains confirmed that the content of the wild-type was low (approx. 1 ng dm^-3) but that it was increased by the introduction of the Agrobacterium Ti plasmid into the Rhizobium strain.Abbreviations CI chemical ionisation - GCMS gas chromatography-mass spectrometry - HPLC high performance liquid chromatography - iPAde isopentenyladenine - MIM multiple ion monitoring     

Habituation in sugarbeet plant cells: Permanent stress or antioxidant adaptative strategy?

Summary Habituation is one of the four neoplastic diseases of plants and occurs spontaneously in plant cell cultures. To date, and even if an epigenetic origin has been previously postulated, the fundamental concept that underlies this neoplastic state remains obscure. Recently, a permanent stress hypothesis has been proposed, using habituated nonorganogenic (HNO) sugarbeet cell line (Beta vulgaris L.altissima) as a model. According to this proposal, the low catalase and peroxidase activities were supposed to be responsible for H₂O₂ accumulation. A supposed lipoxygenase activation would generate LOO° radicals. OH°, produced by the Fenton reaction would be responsible for a lipoperoxidation process, leading to malondialdehyde (MDA) accumulation. In this paper, the elements of this hypothesis have been examined using data previously obtained by several teams, and the permanent stress idea appears less sustainable. Several properties of the habituated nonorganogenic sugarbeet- and some other habituated-cell lines have been described. A more realistic concept emerging from this analysis is that habituated cells exhibit efficient scavenging properties (antioxidant and antilipoperoxidant) against deleterious free radicals produced during cell culture. This thesis is developed in this article.     

Influence of growth regulators on direct embryo formation from leaf explants of Phalaenopsis orchids

Leaf explants of two Phalaenopsis, P. amabilis and P. Nebula, were used to test the effects of auxins (2,4-D, IAA, IBA, NAA), cytokinins (2iP, BA, kinetin, TDZ, zeatin), GA₃, ancymidol, polyamines (putrescine, spermine, spermidine), ACC, AgNO₃ and CoCl₂ on the amount of direct embryo formation on different leaf locations (the cut end, the adaxial side, the abaxial side and the leaf tip). The results showed that there was a genotypic effect on direct embryo formation induced by cytokinins that 13.32 μM BA and 4.92 μM 2iP was the most effective in P. amabilis and P. Nebula, respectively. Besides, explant position highly affected embryogenic competence of leaf cells in both species that the cut end showed highest embryogenic response, the adaxial side was the second, and then the abaxial side and the leaf tip. Altogether, cytokinins tested were all effective in both species, and ACC at 20 μM had 35% of embryogenic response in P. amabilis. However, auxins, GA₃, ancymidol and polyamines were inhibitory in both species.