Interactions between Males of the Lizard Liolaemus tenuis: Roles of Familiarity and Memory

For territorial organisms, recognition of familiar individuals can reduce the frequency and intensity of aggressive encounters (‘dear enemy’ phenomenon), stabilize social systems, and reduce the cost of territory maintenance. Here, we investigated the behavioural events displayed during contests between familiar and unfamiliar individuals in the lizard Liolaemus tenuis (Liolaemidae), a species in which males are territorial. The behaviours recorded were attack, warning, evasion, and submission, and the latencies to the first aggressive (attack or warning) behaviour. Additionally, we assessed the ability of individuals to remember a familiar conspecific after a period without social interaction. Individual males reduced and delayed aggressive behaviour directed towards socially familiar individuals compared with unfamiliar ones. These results suggest that males distinguished between familiar and unfamiliar conspecific males and are in agreement with the ‘dear enemy’ phenomenon. Other behaviours were similar in the contests between familiar and unfamiliar individuals. Recognition of familiar conspecifics was lost after 20 d without social interactions. This may be relevant for interactions with floater males or with neighbours that lose their territory and subsequently attempt to fight for their ex‐neighbour's territory.     

Risk of feather damage explains fault bar occurrence in a migrant hawk,the Swainson's hawk Buteo swainsoni

Fault bars are common stress‐induced feather abnormalities that could produce feather damage thus reducing flight performance. For that reason, it has been hypothesized that birds may have evolved adaptive strategies that reduce the costs of fault bars (the ‘fault bar allocation hypothesis’). An untested prediction of this hypothesis is that fault bars in important feathers for flight (wing and tail) should be less abundant where they produce more feather damage. We tested such a prediction using moulted wing and tail feathers of the long‐distance migrant Swainson's hawk Buteo swainsoni in its Argentinean wintering quarters. We recorded the occurrence of fault bars of different strengths (light, medium and strong) and the damage (lost of a portion of the vane) produced by them. The occurrence of fault bars was very variable, with strong ones being rare throughout and light and medium fault bars being more frequent in the tail than in the wing. Risk of feather damage was similarly high and low across feather groups for strong and light fault bars, respectively, and higher in the wing than in the tail for medium strength. The occurrence of fault bars of different strengths on different feather groups was negatively correlated with their propensity to produce feather damage. At low damage risk (<5%), the occurrence of fault bars was highly variable depending on the feather group, but above 5% of feather damage the occurrence of fault bars was highly reduced throughout. Our results supports the ‘fault bar allocation hypothesis’ of natural selection reducing fault bar occurrence where fault bars are more risky, but further suggest that selection pressure could be relaxed in other instances, leaving the way free for other mechanisms to shape fault bar occurrence.     

Comparative study of helminth parasites of fishes from the Mogi Guassu river, collected during expeditions between 1927 and 1985

This paper concerns the parasitism of Nematoda, Trematoda, Acanthocephala and Cestoda from 1027 fishes of 45 species from Mogi Guassu river, examined in the years 1927, 1946, 1947, 1962, 1983 and 1985 as a contribution to the knowledge of the parasitological fauna in 58 years. Thirty two species of nematodes, 21 of trematodes, 3 of acanthocephalans and 2 of cestodes are reported. New hosts are presented for the nematodes Cucullanus pinnai, Spirocamallanus inopinatus and Travnema travnema, for the trematode Pararhipidocotyle jeffersoni and for the acanthocephalan Gorytocephalus spectabilis. New measurements for the trematode Creptotrema lynchy, tables, graphics and a list of the examined hosts with their parasites are presented.     

Doxorubicin and epirubicin iron-induced generation of free radicalsIn vitro. A comparative study

To ascertain any differences in myocardial injury exerted by the anthracyclines doxorubicin and epirubicin, their ability to generate oxygen free radicals when mixed with Fe(II) was examined in vitro using an oxygen electrode. 5–250 g/ml doxorubicin or epirubicin consumed oxygen when mixed with 50 or 100 mol/1 Fe(II). Addition of 75 mol/1 cytochrome C showed that of the consumed oxygen, approximately 80% entered the monovalent pathway of oxygen reduction. The strong inhibitory effect of 250 mg/1 catalase indicates that most of the superoxide radicals generated are further reduced to hydrogen peroxide by both anthracyclines. Addition of metal chelators DTPA (100/mol/1), or DDTC (50 mol/1) did not affect oxygen consumption, whereas EDTA (100/mol/1) or desferrioxamine (100 mol/1) with anthracyclines and Fe(II) rather stimulated oxygen consumption. It is concluded that there are no significant differences in the amount or proportion of generated oxygen free radicals between doxorubicin and epirubicin when mixed with Fe(II) in a cell-free system in vitro. Thus, the ability of the anthracyclines, in conjunction with iron alone, to generate radicals does not explain the differences of the drugs in causing myocardial injury.     

Factors Involved in Hydrolysis of Microcrystalline Cellulose by Acetivibrio cellulolyticus

Acetivibrio cellulolyticus cellulase obtained by the water elution of residual cellulose from the growth medium was compared with the cellulase activity present in culture supernatants. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated that water elution released most of the protein bands which adhered to undigested cellulose from the culture medium. The enzyme in the culture supernatant and that eluted from residual cellulose had specific activities for Avicel hydrolysis that were 20- to 40-fold greater than that of Trichoderma reesei cellulase. However, Ca²⁺ and a reducing agent such as dithiothreitol were required for maximum Avicel hydrolysis rates by these A. cellulolyticus enzyme preparations. The effect of these agents on p-nitrophenyl lactopyranoside hydrolysis suggested that they were required by an exoglucanase component. Supernatant enzyme preparations contained large amounts of carbohydrate which was separated from most of the cellulase protein by phenyl-Sepharose chromatography. Removal of this carbohydrate, which interfered with protein fractionations, allowed for an activity stain analysis of the supernatant enzyme.     

On the mountain top with Mr. Osterhout

George E. Osterhout, an amateur botanist, collected mainly in Colorado between 1893 and 1936. A brief account of his career and character; a list of his proposed new species and new combinations; and his bibliography.     

The metabolism of deoxyguanosine in mitochondria. Characterization of the uptake process

Summary The uptake of deoxyguanosine by rat liver mitochondria was characterized. The process required an intact mitochondrial membrane and exhibited a dependence on added phosphate. Deoxyguanosine uptake was minimally influenced by Mg²⁺ or Mn²⁺, but Ca²⁺ at concentrations above 0.5 mM were detrimental. Of the deoxynucleosides tested, only deoxyinosine inhibited the uptake of deoxyguanosine. The ribonucleoside guanosine was not observed to compete with its deoxynucleoside analog. Known inhibitors of nucleoside transport, cytochalasin B and NBMPR, did not block deoxyguanosine uptake, but the sulfhydryl reagents NEM and pCMB were both inhibitory. The uptake of deoxyguanosine was shown to be a saturable process and an apparent Km of 0.64 M was calculated from a Hanes plot.     

Plant feeding of yellow baboons (Papio cynocephalus) in Mikumi national park,Tanzania, and the relationship between seasonal feeding and immature survival

Focal-animal feeding data obtained from 64 adult baboons during a 3-year period were used together with equivalent data from 46 infants to evaluate hypotheses predicting selection for a birth peak and to study the baboon’s eclectic/selective feeding adaptation, with emphasis on differential feeding by sex, developmental trends, and seasonal use of food classes (fruit, leaf, flower, grass, etc.). The findings suggest that feeding conditions are better in the wet season than in the dry season. Despite large sexual dimorphism, estimates of total amounts eaten were virtually identical for males and females. Infants used all of the same plant-food classes as adults, but proportional differences occurred for some food classes in amounts eaten. Foods eaten proportionately less by infants were probably harder for them to obtain and process or were chosen through inexperience or for exploration. There was considerable between-year variation in amounts of food classes eaten, but the within-year standard deviations were similar, as were also the mean amounts eaten per year. An eclectic/selective feeding adaptation has the advantage of permitting long-run acquisition of adequate nutrition within a context of high feeding variation from season to season and year to year. Mixed results were obtained from hypotheses about selection for a birth peak. Although a peak occurred in the early dry season, this was not the optimal time of birth for survival. Survival was highest for individuals born in the late wet season, when the availability and probably the quality of food for lactating mothers were greatest.