Competition for nectar resources does not affect bee foraging tactic constancy

1. Competition alters animal foraging, including promoting the use of alternative resources. It may also impact how animals feed when they are able to handle the same food with more than one tactic. Competition likely impacts both consumers and their resources through its effects on food handling, but this topic has received little attention. 2. Bees often use two tactics for extracting nectar from flowers: they can visit at the flower opening, or rob nectar from holes at the base of flowers. Exploitative competition for nectar is thought to promote nectar robbing. If so, higher competition among floral visitors should reduce constancy to a single foraging tactic as foragers will seek food using all possible tactics. To test this prediction, field observations and two experiments involving bumble bees visiting three montane Colorado plant species (Mertensia ciliata, Linaria vulgaris, Corydalis caseana) were used under various levels of inter- and intra-specific competition for nectar. 3. In general, individual bumble bees remained constant to a single foraging tactic, independent of competition levels. However, bees that visited M. ciliata in field observations decreased their constancy and increased nectar robbing rates as visitation rates by co-visitors increased. 4. While tactic constancy was high overall regardless of competition intensity, this study highlights some intriguing instances in which competition and tactic constancy may be linked. Further studies investigating the cognitive underpinnings of tactic constancy should provide insight on the ways in which animals use alternative foraging tactics to exploit resources.     

Crime or affliction? Rape in an African community

Amongst the Gush of southwestern Kenya instances of rape are frequently reported; this was true also in the colonial period and yet it seems that those cases which come to the notice of the authorities are few compared with the numbers which actually occur. While certain features of the traditional culture seem to have encouraged violent sexual assault, because in a patrilocal society miscreants are likely to victimize their relatives, that is women who are sexually taboo, the crime is considered a sacrilegious matter to be dealt with in the family, not by the secular authorities. Given the sacrilegious nature of the act the Gush are convinced that such behavior is involuntary and that the criminal is not a criminal but an afflicted person, motivated by the malevolence of the ancestral spirits or of jealous neighbors and kin. The author uses case material to illustrate various aspects of the Gush belief system in regard to criminal behavior in general and rape in particular.     

The impact of ticks on pheasant territoriality

Pheasants are competent reservoir hosts for the Lyme disease spirochaete, Borrelia burgdorferi s.l., and carry large, but highly over-dispersed, infestations of the vector ticks, Ixodes ricinus . The effects of experimental reduction of tick infestation levels on the survival and territorial behaviour of male pheasants were studied. Over three years in two woodlands in southern England, birds were marked individually and half were fitted with a slow-release acaricide, which substantially reduced their tick burdens from March to August. Acaricide treatment affected reproductive success but had no discernible impact on the survival rates of male pheasants. The degree of wattle inflation by males, an indicator of territorial status and a correlate of harem acquisition, was significantly greater among treated males. In each year, a significantly higher proportion of treated (overall 44%) than control (22%) males acquired harems. Males that acquired females ranged over small areas on field edges. By contrast, those with no females ranged more widely in woods and the adjoining fields, increasing their exposure to questing ticks. The relative contribution of such roving males to tick-borne pathogen transmission may thus increase.     

Dream Imagery and Emotion.

The relationship between prominent visual imagery and emotion within dreams was investigated in relation to E. Hartmann's (1996) contextualizing image (CI) theory and M. Seligman and A. Yellen's (1987) dual imagery theory. Fifty-nine students recorded dreams over a 2-week period and submitted 115 dreams for analysis. Participants recorded ratings of emotion type and emotion intensity in each scene. Prominent visual images were identified and scored for intensity and detail by independent judges. As hypothesized from Hartmann's theory, there was a significant positive relationship between CI intensity and emotion intensity in the CI scene, emotion intensity generally peaked in the CI scene, and dreams containing a CI had higher overall ratings of emotion intensity than non-CI dreams. The result for the correlation of detail of prominent imagery with emotion was inconclusive, with a low positive correlation across CI scenes. This raises the possibility that the CI is not a unitary construct. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inactivation of factor Va by plasmin

The inactivation of Factor Va by plasmin was studied in the presence and absence of phospholipid vesicles and calcium ions. The cleavage patterns of bovine Factor Va and its isolated subunits were analyzed using polyacrylamide gel electrophoresis, and the progress of inactivation was monitored by clotting assays and measurements of prothrombin activation using 5-dimethylaminonaphthalene-1-sulfonylarginine-N-(3-ethyl-1,5-penta nediyl)amide. In addition, the ability of prothrombin and Factor Xa to protect Factor Va from inactivation by human plasmin was examined. The data presented indicate that the cofactor Factor Va is inactivated rapidly upon its interaction with human plasmin. The rate of inactivation is significantly enhanced in the presence of phospholipid vesicles, suggesting that the inactivation process is a membrane-bound phenomenon. The isolated D component (heavy chain of factor Va) was found to be slowly degraded by human plasmin, giving rise to cleavage products different from those obtained with activated protein C and Factor Xa. However, the 48- and 30-kDa fragments obtained from human plasmin degradation of component E (light chain of Factor Va) appear to be similar to those obtained following the proteolysis of the same subunit by activated protein C and Factor Xa.     

EXTERNAL MORPHOLOGY AND PIGMENTATION OF THE VAQUITA, PHOCOENA SINUS (CETACEA: MAMMALIA)

The vaquita, Phocoena sinus , is a porpoise in the family Phocoenidae that lives only in the Gulf of California. The external appearance of P. sinus was unknown until 13 fresh specimens were recently examined. The most obvious morphological feature distinguishing P. sinus from its two congeners is the proportionately higher dorsal fin. The most striking features of the pigmentation pattern are the large black eye patches and the black upper and lower lip patches. In both areas, the pigmentation contrasts sharply with the surrounding light gray coloration. The total lengths of the specimens ranged from 70.3 cm (a neonate) to 143.5 cm (an adult female).     

Synthesis of acetone glycerol acyl esters by immobilized lipase ofMucor miehei

Summary The applications of immobilized lipase ofMucor miehei for the synthesis of acetone glycerol acyl ester from acetone glycerol and fatty acid, which is the first step for monoglyceride production was investigated. With a high oleic acid to acetone glycerol ratio (O/A, mol/mol), a high catalytic activity was observed under low water content in the reaction mixture. By the combination of high O/A ratio (>3) and removal of water which was produced during the reaction, the conversion degree was increased to almost 100%. With the O/A ratio of 3, the approximate half-life of the immobilized lipase and productivity of ester was estimated to be 20 days and 869 g product/g immobilized enzyme per 2 half-lives, respectively.     

Appearance of alpha-smooth muscle actin in human eye lens cells of anterior capsular cataract and in cultured bovine lens-forming cells

Using light and electron-microscopic immunolocalization techniques, and gel electrophoresis combined with immunoblotting, we have examined the expression of cytoskeletal proteins in normal human fetal, child and adult lenses, in human anterior capsular cataract and in bovine lens cells in vivo and in vitro. In this report, we focus our observations on the pattern of actin-isoform expression during normal and pathological situations in vivo and culture conditions. We have noted that cells of developing and mature human lenses as well as bovine lens cells in situ contain only beta- and gamma-actins. In contrast, alpha-smooth muscle (alpha-sm) actin, an isoform typical of smooth muscle differentiation, was demonstrated in bovine lens cells at different times of culture. Moreover, the multilayered cells observed in the subcapsular zone of human anterior capsular cataract were characterized by the presence of alpha-sm actin. Thus, extensive changes in actin-isoform expression take place in lens cells growing in culture and may also occur during cataractogenesis. The biological meaning of the appearance of a marker of myoid differentiation in the ectodermally derived lens-forming cells is discussed.     

Effect of colchicine on lysosomal structures in maturation-ameloblasts of the rat incisor

Summary The lysosomal systems in maturation-ameloblasts affected by colchicine were examined using trimetaphosphatase cytochemistry. Demineralized segments of rat incisor were incubated for trimetaphosphatase. At all time intervals, lysosomal structures exhibited reduced enzyme reactivity and were clustered in the Golgi region of the cell. Both ruffle-ended and smooth-ended ameloblasts maintained essentially normal morphology up to 4 h after colchicine injection, except for some migration of organelles. After 8 h, the ruffled border was markedly modified and the associated dense granular material was no longer present. Changes in the lysosomal system and ruffled border indicate interference by colchicine with a putative resorptive function of the maturation-ameloblasts.