Construction of a Normalized cDNA Library for the Trypanosoma cruzi Genome Project

Sequencing of the Trypanosoma cruzi genome is underway. Expressed sequence tags, obtained from cDNA libraries, facilitate mapping and gene discovery. The efficiency of large-scale generation of such tags is increased when using normalized cDNA libraries, where the frequency of individual clones is brought within a narrow range. Repetitive sequencing of abundant clones is therefore minimized. We constructed a normalized cDNA library from epimastigotes of clone CL Brener, and the efficiency of normalization of representative clones was assessed and shown to be adequate. The normalized cDNA library has been distributed to several groups and large-scale sequencing is currently in progress.     

Host refuges and spatial patterns of parasitism in an endophytic host–parasitoid system

Abstract. 1. Larvae of Tephritis conura Loew (Diptera: Tephritidae) live gregariously in flower heads of Cirsium heterophyllum (L.) Hill (Cardueae). They are attacked by the endoparasitic wasps Eurytoma sp. near tibialis Boheman (Hymenoptera: Eurytomidae) and Pteromalus caudiger (Graham) (Hymenoptera: Pteromalidae).
2. The responses of the parasitoids to different host patch sizes were investigated from the analysis of field samples. At the host population level, overall probabilities of parasitism were independent of host numbers per flower head or showed a tendency to inverse density-dependence for both parasitoid species.
3. Measurements of ovipositor length in Eurytoma and P.caudiger indicated that parts of the flower head constitute a structural refuge from parasitism.
4. The accessibility of hosts in a flower head was found to differ markedly, depending on larval locations and flower head characters. In spite of this high variability, similar average percentages of larvae were accessible to the parasitoids in each patch size class.
5. High variability of oviposition success in laboratory experiments can be explained by random locations of hosts in the flower heads.     

SONG STRUCTURE AND SINGING BEHAVIOUR OF WILLOW WARBLER PHYLLOSCOPUS TROCHILUS ACREDULA IN POPULATIONS OF LOW AND HIGH DENSITY

ABSTRACT

Song structure and singing behaviour in two nesting populations of Willow Warbler Phylloscopus trochilus acredula of different density were studied in Moscow and Kostroma Regions, Russia, from 1994–1997. In total 520 songs of 9 males from the low-density population and 566 songs of 12 males from the high density population were analysed. Singing periods in the high density Willow Warbler population (11 males, 758 min.) were longer (58% of the time) than in the low density population (13 males, 866 min.) (58%). In the high density population, 51% of singing time consisted of “singing duels” (singing in gaps between the songs of a neighbouring male, and singing during the singing of a neighbouring male), while in the low density population only 7% did. The initial phrases of Willow Warbler songs were significantly longer in the high density population, with up to 9–13 elements, while there were no occurrences of this length in the low density population. Songs as a whole were longer and more variable in the high density population. Thus changes in structure, singing activity and behaviour are linked to male-male interaction and density of the nesting community.     

Terrestrial Activity in Pitheciins (Cacajao,Chiropotes, and Pithecia)

Neotropical monkeys of the genera Cacajao, Chiropotes, and Pithecia (Pitheciidae) are considered to be highly arboreal, spending most of their time feeding and traveling in the upper canopy. Until now, the use of terrestrial substrates has not been analyzed in detail in this group. Here, we review the frequency of terrestrial use among pitheciin taxa to determine the ecological and social conditions that might lead to such behavior. We collated published and unpublished data from 14 taxa in the three genera. Data were gleaned from 53 published studies (including five on multiple pitheciin genera) and personal communications of unpublished data distributed across 31 localities. Terrestrial activity was reported in 61% of Pithecia field studies (11 of 18), in 34% of Chiropotes studies (10 of 29), and 36% of Cacajao studies (4 of 11). Within Pithecia, terrestrial behavior was more frequently reported in smaller species (e.g. P. pithecia) that are vertical clingers and leapers and make extensive use of the understory than in in the larger bodied canopy dwellers of the western Amazon (e.g. P. irrorata). Terrestrial behavior in Pithecia also occurred more frequently and lasted longer than in Cacajao or Chiropotes. An apparent association was found between flooded habitats and terrestrial activity and there is evidence of the development of a “local pattern” of terrestrial use in some populations. Seasonal fruit availability also may stimulate terrestrial behavior. Individuals also descended to the ground when visiting mineral licks, escaping predators, and responding to accidents such as a dropped infant. Overall, the results of this review emphasize that terrestrial use is rare among the pitheciins in general and is usually associated with the exploitation of specific resources or habitat types. Am. J. Primatol. 74:1106‐1127, 2012. © 2012 Wiley Periodicals, Inc.     

Mating or ovipositing? A crucial decision in the life history of the cabbage aphid parasitoid Diaeretiella rapae (M’Intosh)

1. The reproductive fitness of a parasitoid depends on its mating and ovipositing success. Virgin haplodiploid females can reproduce, but produce only males, and may diminish fitness by producing more male offspring than required. Therefore, females must decide on whether to mate or oviposit first. 2. This study was conducted to assess the mating versus ovipositing decision and its impact on the reproductive fitness of Diaeretiella rapae (Hymenoptera: Aphididae), an endoparasitoid of the cabbage aphid Brevicoryne brassicae (Hemiptera: Aphididae). 3. When newly emerged females were given a choice between mating and ovipositing, about 62% of D. rapae females preferred to mate before ovipositing. Those females who oviposited before mating parasitised only 10% of the available aphids. After mating, females superparasitised their hosts with fertilised eggs, which resulted in a highly female‐biased sex ratio in the offspring. 4. Mating success was very high (91%) in the presence of hosts (cabbage aphid nymphs) compared with that in the absence of aphids. However, mating success was not influenced by the quality (size) of the hosts present in the mating arena, despite a parasitoid preference for larger hosts during oviposition. The time between pairing and mating was also shorter in the presence of host aphids. The mean number of aphids parasitised and the parasitism rate were significantly greater after mating.     

Differential Effect of Ribosome-Inactivating Proteins on Plant Ribosome Activity and Plant Cells Growth

The effect of ribosome-inactivating proteins (RIPs), eithersingle-chain or toxins, was studied on plant ribosomes. RIPsdid not affect ribosomes from their own plants, while inhibitingto a variable extent protein synthesis by heterologous plantribosomes. Ricin stimulated and PAP—S inhibited the growthof carrot cells in culture. Key words: Plant ribosomes, Ribosome-inactivating proteins, Protein synthesis, Ribosome specificity, Plant cell cultures     

THE INFLUENCE OF HUMIDITY, PHOTOPERIOD, AND TEMPERATURE ON THE DORMANCY AND ACTIVITY OF HELIX LUCORUM L. (GASTROPODA, PULMONATA)

The dormancy of Helix lucorum from N. Greece is controlled primarilyby low humidity. Photoperiod and temperature have no directeffect, except in the anomalous combination of long cool daysor short hot days. Adults hibernate more readily than juveniles.The duration of hibernation (before rejection of the calcareousepiphragm) is only slightly shorter at high temperatures. (Received 15 December 1985;