Microgeographic genetic structure and intraspecific parasitism in the ant Leptothorax nylanderi

1. Genetic colony structure of the small central European ant Leptothorax nylanderi is affected strongly by ecological constraints such as nest site availability and intraspecific social parasitism. 2. Although L. nylanderi is generally monogynous and monandrous, more than a quarter of all nests collected in a dense population near Würzburg, Germany, contained several matrilines. As shown by microsatellite analysis, the average nest‐mate relatedness in these nests was 0.20. Genetically heterogeneous nests arise from nest take‐over by alien colonies or founding queens, a result of severe competition for nest sites. 3. In summer, more than one‐third of all colonies inhabited several nest sites at a time. Polydomy appears to be rather limited, with two or three nests belonging to a single polydomous colony. 4. Queens appear to dominate male production; only a small fraction (8%) of males was definitively not progeny of the queen present but might have been worker progeny or offspring of another queen. 5. Strong evidence for heterozygote deficiency was found and a total of nine diploid males was discovered in two colonies. These findings suggest deviation from random mating through small, localised nuptial flights.     

Specificity of GlcNAc-PI de-N-acetylase of GPI biosynthesis and synthesis of parasite-specific suicide substrate inhibitors.

The substrate specificities of Trypanosoma brucei and human (HeLa) GlcNAc-PI de-N-acetylases were determined using 24 substrate analogues. The results show the following. (i) The de-N-acetylases show little specificity for the lipid moiety of GlcNAc-PI. (ii) The 3'-OH group of the GlcNAc residue is essential for substrate recognition whereas the 6'-OH group is dispensable and the 4'-OH, while not required for recognition, cannot be epimerized or substituted. (iii) The parasite enzyme can act on analogues containing betaGlcNAc or aromatic N-acyl groups, whereas the human enzyme cannot. (iv) Three GlcNR-PI analogues are de-N-acetylase inhibitors, one of which is a suicide inhibitor. (v) The suicide inhibitor most likely forms a carbamate or thiocarbamate ester to an active site hydroxy-amino acid or Cys or residue such that inhibition is reversed by certain nucleophiles. These and previous results were used to design two potent (IC50 = 8 nM) parasite-specific suicide substrate inhibitors. These are potential lead compounds for the development of anti-protozoan parasite drugs.     

Fibroblast growth factor signaling in Caenorhabditis elegans.

Growth factor receptor tyrosine kinases (RTKs), such as the fibroblast growth factor receptor (FGFR), play a major role in how cells communicate with their environment. FGFR signaling is crucial for normal development, and its misregulation in humans has been linked to developmental abnormalities and cancer. The precise molecular mechanisms by which FGFRs transduce extracellular signals to effect specific biologic responses is an area of intense research. Genetic analyses in model organisms have played a central role in our evolving understanding of these signal transduction cascades. Genetic studies in the nematode C. elegans have contributed to our knowledge of FGFR signaling by identifying genes involved in FGFR signal transduction and linking their gene products together into signaling modules. This review will describe FGFR-mediated signal transduction in C. elegans and focus on how these studies have contributed to our understanding of how FGFRs orchestrate the assembly of intracellular signaling pathways.     

DNA helicase-mediated packaging of adeno-associated virus type 2 genomes into preformed capsids.

Helicases not only catalyse the disruption of hydrogen bonding between complementary regions of nucleic acids, but also move along nucleic acid strands in a polar fashion. Here we show that the Rep52 and Rep40 proteins of adeno-associated virus type 2 (AAV-2) are required to translocate capsid-associated, single-stranded DNA genomes into preformed empty AAV-2 capsids, and that the DNA helicase function of Rep52/40 is essential for this process. Furthermore, DNase protection experiments suggest that insertion of AAV-2 genomes proceeds from the 3' end, which correlates with the 3'-->5' processivity demonstrated for the Rep52/40 helicase. A model is proposed in which capsid-immobilized helicase complexes act as molecular motors to 'pump' single-stranded DNA across the capsid boundary.     

Crystal structure of a dynamin GTPase domain in both nucleotide-free and GDP-bound forms.

Dynamins form a family of multidomain GTPases involved in endocytosis, vesicle trafficking and maintenance of mitochondrial morphology. In contrast to the classical switch GTPases, a force-generating function has been suggested for dynamins. Here we report the 2.3 A crystal structure of the nucleotide-free and GDP-bound GTPase domain of Dictyostelium discoideum dynamin A. The GTPase domain is the most highly conserved region among dynamins. The globular structure contains the G-protein core fold, which is extended from a six-stranded beta-sheet to an eight-stranded one by a 55 amino acid insertion. This topologically unique insertion distinguishes dynamins from other subfamilies of GTP-binding proteins. An additional N-terminal helix interacts with the C-terminal helix of the GTPase domain, forming a hydrophobic groove, which could be occupied by C-terminal parts of dynamin not present in our construct. The lack of major conformational changes between the nucleotide-free and the GDP-bound state suggests that mechanochemical rearrangements in dynamin occur during GTP binding, GTP hydrolysis or phosphate release and are not linked to loss of GDP.     

Female marmoset monkeys (Callithrix jacchus) can be identified from the chemical composition of their scent marks.

The present study analyzed 42 organic solvent extracts of scent mark pools from five dominant female common marmosets by gas chromatography (GC) and combined GC and mass spectrometry. We determined whether there were qualitative or quantitative differences between the chemical composition of scent marks from individual females. Gas chromatography and mass spectral analysis detected the same 162 chemicals in 86% (36/42) of scent mark pools from five dominant females. This near identical chemical composition of scent marks suggested there were few, if any, qualitative differences between the chemical composition of scent marks from individual females. Instead, quantitative differences in scent may provide the key factor distinguishing individual females. Using the relative concentration of highly volatile chemicals detected by GC in scent marks, linear discriminant analysis classified scent mark pools to their correct donor approximately 91% of the time. Such highly reliable statistical matching of scent to donor suggested that each individual female common marmoset has a unique ratio of highly volatile chemicals in their scent marks which may permit individual identification of females from odors in their scent alone.     

1-X-3 motif in inter-protein recognition: structures, widespreading and possible practical application.

Similarities in the discrete mode and size of contact areas of a wide range of protein complexes allows us to suggest the existence of a limited number of types of inter-protein interactions. Comparison of structures of bound determinants indicates that the double-module, 1-X-3 type of motif is widespread in recognition processes. Thus, in many cases, the sites of ligand recognition are formed by two significant amino acids and separated by insignificant ones. Typical examples of such motifs are the RGD sequence of some adhesive and haemostatic proteins, the primary sites for plasminogen sorption on the fibrin network, the reactive sites of protein inhibitors of serine proteinases, and the sites for activation of the hydrolysis of protein pro-forms and receptors. It is assumed that there is widespread double-module determinants in many inter-protein interactions.     

Regulation of Apterous activity in Drosophila wing development.

Apterous is a LIM-homeodomain protein that confers dorsal compartment identity in Drosophila wing development. Apterous activity requires formation of a complex with a co-factor, Chip/dLDB. Apterous activity is regulated during wing development by dLMO, which competes with Apterous for complex formation. Here, we present evidence that complex formation between Apterous, Chip and DNA stabilizes Apterous protein in vivo. We also report that a difference in the ability of Chip to bind the LIM domains of Apterous and dLMO contributes to regulation of activity levels in vivo.