The Tommotian goes international

Rozanov, A. Yu. et al . (Raaben, M. E., ed.) 1981: The Tommotian Stuge and the Cambrian Loner Boundary Problem . 359 pp. (Tranalated from Russian by S. Guha.) Amerind Publishing Co. Pvt. Ltd., New Delhi, Price $US 35.00.     

Review of Ptycholaimellus Cobb (Nematoda, Chromadoridae), with descriptions of three species

Nematodes of the genus Ptycholaimellus Cobb, 1920 are unique in possessing a collar by which the head is separated from the body. The collar is raised from a groove at the border between the neck and the remainder of the body. The contents of the ventral gland cell are emptied in the groove in at least 9 out of 14 species. It is suggested that the amphids are located in the groove. Fourteen species are considered to belong to Ptycholaimellus . Two Ptycholaimellus species are described as new to science, that is, P. jacobi sp.n. and P. vincxae sp.n.; P. ponticus (Fihpjev, 1922) is redescribed. Ptycholaimellus ponticus sensu Stekhoven (1950) and Boucher (1972) from the Mediterranean off France differs from the other Ptycholaimellus species by its subcuticular ornamentation and shape of spicules, hence these specimens are regarded as belonging to a new species: Ptycholaimellus boucheri sp.n. Chromadorissa inaequibulba Aminova & Galtsova, 1978 is transferred to Ptycholai- mellus as P. inaequibulbus. Ptycholaimellus ponticus from Europe and P pandispiculatus (Hopper, 1961) from the east coast of North America are assumed to have colonized brackish waters independently.     

Fungal chemical defence alters density‐dependent foraging behaviour and success in a fungivorous soil arthropod

1. Aggregative behaviour in fungivorous soil arthropods is widespread; its adaptive value, however, is largely unknown. In this study, the spatial foraging behaviour of a collembolan, Folsomia candida, and the fitness consequences of feeding at different densities on the filamentous fungus Aspergillus nidulans were investigated. The effect of two fungal strains were compared; a wild‐type (wt) and a transgenic strain that lacks the ability to express the global secondary metabolite regulator LaeA (ΔlaeA). 2. In laboratory foraging tests, F. candida exhibited aggregated distributions of individuals across four distinct fungal colonies that were arranged in short distances from each other. By quantifying the extent of the feeding damage at each single colony, a more evenly distributed feeding activity was found among wt colonies than among chemical‐deficient colonies. 3. In a fitness experiment, where collembolans at different densities were restricted to feed on single A. nidulans colonies, mean growth rate of F. candida was positively related to density on the wt A. nidulans strain, but negatively related to density on the chemical‐deficient strain. 4. Depending on the fungus' ability to express secondary chemicals and availability of fungal food sources, F. candida may employ different foraging strategies: (i) avoidance of prolonged feeding on single colonies in a rich habitat (travel costs low), and (ii) intensified group feeding on single colonies in a resource‐limited habitat (travel costs high). It was hypothesised that flexibility in fungivore foraging behaviour (clumping vs. spreading feeding activity) is adaptive because it allows avoidance/overcoming induced fungal chemical defence.     

Sensing,Threading, Orienting,and Cutting Polymers with Rigid-Rod Pores

This short review describes synthetic pores that are made from rigid-rod molecules and can bind oligo-and polymers such as polyacetylenes, p-oligophenyls, terpenoids, polypeptides, polysaccharides, and oligonucleotides. The spotlight is on recent breakthroughs to image the longtime elusive pore-polymer host-guest complexes as single giant pseudorotaxanes.     

Two-Dimensional Solid-State NMR Applied to a Chimeric Potassium Channel

Solid-state NMR (ssNMR) represents a spectroscopic method to study membrane protein structure and dynamics in lipid bilayers. We present two-dimensional correlation experiments conducted on a fully [¹³C,¹⁵N] labeled version of a chimeric potassium (KcsA-Kv1.3) channel. Data obtained by using two different ion concentrations suggest a structural conservation of the selectivity filter region. SsNMR experiments conducted at two different temperatures point to differential molecular dynamics of the channel.     

Mild stress during development affects the phenotype of great tit Parus major nestlings: a challenge experiment

Conditions experienced during early development may affect both adult phenotype and performance later during life. Phenotypic traits may hence be used to indicate past growing conditions and predict future survival probabilities. Relationships between phenotypic markers and future survival are, however, highly heterogeneous, possibly because poor‐ and high‐quality individuals cannot be morphologically discriminated when developing under good environmental conditions. Sub‐optimal breeding conditions, in contrast, may unmask poor‐quality individuals in a measurable way at the morphological level. We thus predict stronger associations between phenotype and performance under stress. In this field study, we test this hypothesis, experimentally challenging the homeostasis of great tit (Parus major) nestlings by short‐term deprivation of parental care, which had no immediate effect on nestling fitness. The experiment was replicated during two subsequent breeding seasons with contrasting ambient weather conditions. Experimental (short‐term) stress affected tarsus growth but not residual mass at fledging, whereas ambient (continuous) stress affected residual mass but not tarsus growth. Short‐term stress effects on tarsus length and tarsus fluctuating asymmetry were only apparent when ambient conditions were unfavourable. Residual mass and hatching date, but none of the other phenotypic traits, predicted local survival, whereby the strength of the relationship did not vary between both years. Because effects of stress on developmental homeostasis are likely to be trait‐specific and condition‐dependent, studies on the use of phenotypic markers for individual fitness should integrate multiple traits comprising different levels of developmental complexity. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 103–110.