Sub-optimal pit construction in predatory ant lion larvae (Myrmeleon sp.)

The impacts on energy gains of two aspects of ant lion pit architecture were investigated in a natural population of pit-building ant lion larvae (Myrmeleon sp.) in Costa Rica. Field and laboratory settings were used to examine the impacts of circumference and depth of the pit on net energy gain rate. An optimization model predicted a point optimum circumference and angle of depression in an unconstrained system, and positive correlations between body mass, pit circumference, and pit angle of depression in the presence of physiological constraints on both measures. Such a physiological constraint is possible in this system due to a large one-time construction cost. All of these correlations were observed in a lab setting with filtered substrate and no competition; though none were significant in the field. Individuals additionally constructed wider, shallower pits in the field. These results are consistent with an angle of depression that is limited by the angle of repose of the substrate in the field, rather than physiology. These results provided suggestive evidence for sub-optimal pit dimensions in Myrmeleon sp., and for the importance of substrate type in understanding the architecture of natural ant lion pits. The model predicted that the frequency of relocation would not affect the optimal angle of depression, but it would affect the optimal pit circumference to a degree proportional to the square root of the change in the average time an ant lion occupies a single pit. These findings challenge the widely held assumption of adaptive optimality in animal foraging.     

Identification of new mutant alleles of <Emphasis Type="Italic">pcc1</Emphasis> in the homobasidiomycete <Emphasis Type="Italic">Coprinopsis cinerea</Emphasis>

It is known that a mutation in the pcc1 gene of the homobasidiomycete Coprinopsis cinerea leads to pseudoclamp development and fruit-body formation in a homokaryon without mating. In this study we characterize two strains that were reported previously to exhibit pseudoclamp development and fruiting without mating, together with six new mutants exhibiting the same phenotype. A frame-shift, nonsense, or intron splice site mutation was present within pcc1 in each of the eight mutants. The results suggest that the Pcc1 protein is a key element in a pathway(s) leading to pseudoclamp development and fruiting.     

Host cell range of T-lymphotropic feline leukemia virus in vitro

We compared the host cell range of T-lymphotropic feline leukemia virus (FeLV-T) with that of FeLV subgroup B (FeLV-B) by pseudotype assay in the presence of FeLIX, a truncated envelope glycoprotein of endogenous FeLV. Although both viruses use Pit1 as a receptor and FeLIX does not hamper FeLV-B infection by receptor interference, the host ranges of FeLV-T and -B were not exactly the same, suggesting a different Pit1 usage at the post-binding level. A comparison of Pit1 sequences of various mammalian species indicated that extracellular loop 1 in a topology model deduced with the PHD PredictProtein algorism may be one of the regions responsible for efficient infection by FeLV-T.     

The effect of SEM preparation on pit membrane remnants in vessel element end-walls of primitive angiosperms

Scanning electron microscope (SEM) is necessary to demonstrate presence or absence of pit membranes in possible perforations or the type of pit membrane remnants in perforations in vessel element end-walls of angiosperms, but it was unconfirmed and questionable whether pit membrane absence in pits was affected by the processing and handling before SEM observations. To solve this question, the secondary xylem of four woody species from primitive angiosperms, Illicium henryi Diels. (Illiciaceae), Schisandra rubriflora (Franch.) Rehd. et Wils. (Schisandraceae), Tetracentron sinensis Oliv. and Trochodendron aralioides Sieb. & Zucc. (Trochodendraceae) was chosen and the following techniques were used: (1) fresh materials were examined in low-vacuum with ESEM. (2) Air-dried materials were examined both in low- and high-vacuum with ESEM. (3) Fresh materials fixed in several different fixatives were observed in low-vacuum, respectively. (4) Smooth surface of the material by paraffin section methods was examined in high-vacuum. (5) Materials treated by Jeffrey's Fluid were observed in high-vacuum.Pit membranes and remnants in perforations of fresh material were little different from that of treated materials. Absence of the pit membrane in perforations (pits) in the end-wall was not attributed to the processing and handling. Information of pit membranes and remnants in perforations in end-wall based on the SEM observation might be validly claimed.     

REPRODUCTIVE TOURISM AND THE QUEST FOR GLOBAL GENDER JUSTICE

Reproductive tourism is a manifestation of a larger, more inclusive trend toward globalization of capitalist cultural and material economies. This paper discusses the development of cross‐border assisted reproduction within the globalized economy, transnational and local structural processes that influence the trade, social relations intersecting it, and implications for the healthcare systems affected. I focus on prevailing gender structures embedded in the cross‐border trade and their intersection with other social and economic structures that reflect and impact globalization. I apply a social connection model of responsibility for unjust outcomes and consider strategies to counter structural injustices embedded in this industry. The concluding section discusses policy reforms and proposals for collaborative action to preclude further injustices and extend full human rights to all.     

Two new mononuclear gold(I)-nitrogen [N,N′-di(2,6-methyl)phenylformamidine] complexes: Syntheses and crystal structures

Two gold(I) mononuclear complexes have been prepared by reacting gold(I) tetrahydrothiophene with N,N′-di(2,6-methyl)phenylformamidine. The neutral complex [N,N′-di(2,6-methyl)phenylformamidine)-gold(I) chloride (C₁₇H₂₀AuClN₂) (1), crystallizes in the triclinic group while the cationic [N,N′-di(2,6-methyl)phenylformamidine](tetrahydrothiophene)-gold(I) (C₂₁H₂₈AuN₂S) (2) crystallizes with a nitrate anion in the monoclinic group P2(1)/n. Both compounds are good starting materials for synthetic gold chemistry.     

Orbilia querci sp. nov. and its knob-forming nematophagous anamorph

Orbilia querci, a new nematode-trapping fungus, was found on rotten wood of Quercus sp. in Huai-rou County, Beijing, China. It is characterized by having a tear-shaped spore body in the cylindrical ascospore. Pure culture was obtained from the ascospores. Conidiophores were simple or occasionally branched, bearing a single conidium on the tip. Conidia were spindle-shaped, mostly with 3-septa. Nematodes were captured by means of adhesive stalked knobs. The adhesive knobs were produced frequently on nutritional agar plates even in the absence of challenging nematodes. Its anamorph is placed in Dactylellina and named as D. querci. The sequence divergence of the ITS1 region between the fungus and the other knob-forming species tested was 23.8-33.4%, supporting O. querci as a distinct species. This is the first report of the connection between a knob-forming nematophagous hyphomycete and an Orbilia teleomorph.     

Pea seed-borne mosaic virus seed transmission exploits novel symplastic pathways to infect the pea embryo and is, in part, dependent upon chance

Summary. Seed transmission of pea seed-borne mosaic virus (PSbMV) depends upon symplastic transport of the virus from infected maternal cells to the embryo. Such transport pathways have not been identified in higher plants. To identify these pathways, we have studied the ultrastructure of the tissues and cells around the micropyle of young developing seeds and compared transmitted and nontransmitted virus isolates. A characteristic of PSbMV infection was the presence of cylindrical inclusions positioned over plasmodesmal openings. The presence of cylindrical inclusions on the testa–endosperm boundary wall, together with immunogold labelling for virus-specific products on the wall and in the endosperm, indicated that symplastic connections existed at this interface. Close examination of the endosperm–suspensor boundary at the base of the suspensor revealed discontinuities in the suspensor sheath wall as porelike structures, which the virus might pass through en route to the embryo. A nontransmitted PSbMV isolate was able to invade the maternal tissues of the developing seed but was excluded from the embryo, although it was detected at a low level in the endosperm. Since the endosperm did not support virus replication, it appeared that passive accumulation determined the amount, timing, and location of the virus relative to the base of the suspensor. Rarely, therefore, could the nontransmitted virus isolate reach the correct location in the endosperm at the correct time for embryo infection via the suspensor to occur.Present address: Institute of Genetics, Chinese Academy of Sciences, Beijing, People's Republic of China.Correspondence and reprints: Department of Disease and Stress Biology, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom.Received January 7, 2003; accepted May 19, 2003; published online September 23, 2003     

Connection of Gnomonia intermedia to Discula betulina and its relationship to other taxa in Gnomoniaceae

Discula betulina is a foliar pathogen on birch (Betula) and Gnomonia intermedia is found on overwintered birch leaves. Perithecia of G. intermedia developed in vitro on colonies of D. betulina isolated from birch tissues in late summer, and single ascospores of G. intermedia consistently developed into colonies similar to D. betulina, producing typical D. betulina conidia. Isolates of D. betulina could be grouped into two mating types, which produced fertile perithecia of G. intermedia when mated with each other. Mycelia from single-ascospore and single-conidial isolates were inoculated onto shoots of downy birch, causing lesions and die-back from which D. betulina was consistently isolated. ITS region ribosomal DNA sequence analysis confirmed the results of the morphological and mating studies, and found that the closest known relatives of G. intermedia/D. betulina are Gnomoniella nana and Sirococcus clavigignenti-juglandacearum. The conclusion from these studies is that D. betulina is the anamorph of G. intermedia.