Detection of Penicillin-binding Proteins in the Endosymbiont of the Trypanosomatid Crithidia deanei

ABSTRACT. Growth by serial transfers of the trypanosomatid Crithidia deanei in culture medium containing 1 mg/ml of the β-lactam antibiotics ampicillin or cephalexin resulted in shape distortion of its endosymbiont. The endosymbiont first appeared as filamentous structures with restricted areas of membrane damage. An increase of electron lucid areas was also observed in the endosymbiont matrix. The continuous treatment with β-lactam antibiotics, resulted in endosymbiont membranes fragmentation; and later on the space previously occupied by the symbiont was identified as an electron lucid area in the host cytoplasm. The putative targets of β-lactam antibiotic were two membrane-bound penicillin-binding proteins (PBPs) detected in the Sarkosyl-soluble fraction of purified symbionts labeled with [³H]-benzylpenicillin. The apparent molecular weight of the proteins were 90 kDa (PBP1) and 45 kDa (PBP2). PBP2 represented 85% of the total PBP content in the membrane fraction of the endosymbionts. Competition experiments using the tested antibiotics and [³H]-benzylpenicillin showed that ampicillin and cephalexin have half saturating concentrations considerably higher than [³H]-benzylpenicillin and indicated that PBP1 is the probable lethal target of the antibiotics tested. These results suggest that a physiologically active PBP is present in the cell envelope of C. deanei endosymbionts and may play important roles in the control of processes such as cell division and shape determination.     

Landmark superimposition for taxonomic identification

The identification of organisms is a time-consuming task even for highly specialized researchers. Many ways to accelerate the identification process have been devised – from pictorial keys to automatic, machine identification – with different degrees of success. This paper explores landmark configurations as an aid to taxonomic identification. The basic hypothesis rests on the analogy between human fingerprints and organism landmark configuration. Translated into biological terms, it asks whether individual landmark configurations can be used as diagnostic characteristics for species identification. Water mites of the genus Torrenticola were used as test organisms. The results show that identification can be made simpler through the use of landmark configurations.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 267–274.     

The functions of belly-soaking in Kentish Plovers Charadrius alexandrinus

We tested whether belly-soaking (i.e. wetting of ventral plumage) in incubating Kentish Plovers Charadrius alexandrinus in a hot environment serves to cool overheated eggs, or whether belly-soaking would mainly serve for adult thermoregulation, and egg wetting would be a mere consequence of the ventral feathers of incubating adults being wet. When ambient temperature was high (> 30 °C), body temperature of incubating Kentish Plovers increased with ambient temperatures. When adults departed from nests to belly-soak, egg temperatures were not critical for embryos. However, eggs in exposed nests overheated to levels that may be lethal for embryos when adults left the nests to belly-soak, and adults also employed belly-soaking to cool down overheated eggs when they returned to their nests. Indeed, the cooling rate of eggs was much faster when they were wetted. We conclude that the primary function of belly-soaking in the Kentish Plover is to dissipate body heat in heat-stressed incubating adults, rather than to cool overheated eggs. Eggs overheated as a consequence of short-term interruptions in nest attendance by heat-stressed adults to belly-soak, and Plovers employed secondarily belly-soaking to cool down overheated eggs. These results indicate that adult thermoregulation and egg cooling are not mutually exclusive functions of belly-soaking.     

Undesirable side-effects of water hyacinth control in a shallow tropical reservoir

1. Based on a comprehensive data set collected monthly during 8 years (1997–2004), we evaluated the effects of mechanical removal of Eichhornia crassipes on the limnological characteristics and algal biomass of a polymictic shallow tropical reservoir. 2. Interrupted time series analyses indicated that the limnological responses to macrophyte removal can be classified as an ‘abrupt permanent impact’ implying that the overall mean of the time‐series shifted promptly after intervention. These analyses indicated a significant increase for pH, total phosphorus, total phytoplankton and cyanobacterial biomass, and a decrease in water transparency and CO₂ concentrations in the surface water; also, the increase in water stability, increase of bottom soluble reactive phosphorus (SRP) and decrease in bottom oxygen levels. 3. Cyclic anoxic periods previously observed during springs and summers were replaced by a persistent period of anoxic conditions in the sediment overlying water. Anoxic conditions were suitable for SRP release from sediments. Heavy cyanobacterial blooms became more persistent, maximum biomass (4229 mm³ L⁻¹) was 30 times larger, the blooms frequently reached 2 m and sometimes the bottom of the reservoir, contrasting to the preremoval period in which it reached at most 1 m deep. 4. The long‐term P dynamics in the system, initially driven by allochthonous nutrient loadings were replaced by internal ecological processes. Water hyacinth removal markedly accelerated the process of eutrophication due to internal feedback mechanisms, leading to a switch to a more turbid state. Biological feedback mechanisms were driven by cyanobacterial blooms by enhancing water stability, oxygen anoxia at the bottom and by increasing suitable conditions for P internal loading. These data support the hypothesis of the role of cyanobacterial blooms as an important factor impairing water quality and driving the ecosystem towards a stable degraded state. 5. These findings have important implications for the restoration of shallow stratifying eutrophic lakes, as the alternative degraded state is most likely to occur when compared with their non‐stratifying counterparts. Moreover, feedback mechanisms in tropical and subtropical shallow lakes seem to be stronger than in temperate ones, as stratification events are more likely to occur over the year, intensifying system resilience to restorative strategies.     

Costimulation of resting B lymphocytes alters the IL-4-activated IRS2 signaling pathway in a STAT6 independent manner: implications for cell survival and proliferation

INTRODUCTIONThe inappropriate enhancement of lymphocytesurviVal due to a block in programmed cell deathand/or an enhancement of entry into the cell cyclecan contribute to the abnormal expansion of clonesresulting in tumorigenesis or the breakdown of pe-ripheral self-toleranced, 2]. Proper lymphocytehomeostasis is critical for normal immune functionand is maintained by a complex series of cellularinteractions and the action of secreted cytokines.Illterleukin-4 (IL-4), a cytokine produced …     

Mutational analysis of the <Emphasis Type="Italic">GLA</Emphasis> gene in Mexican families with Fabry disease

Fabry disease (FD) is a lysosomal storage disorder, which develops due to a deficiency in the hydrolytic enzyme, α-galactosidase A (α-Gal A). Alpha-Gal A hydrolyzes glycosphingolipid globotriaosylceramide (Gb3), and an α-Gal A deficiency leads to Gb3 accumulation in tissues and cells in the body. This pathology is likely to involve multiple systems, but it is generally considered to affect primarily vascular endothelium. In this study, we investigated mutations in the GLA gene, which encodes α-Gal A, in Mexican families with FD. We included seven probands with FD that carried known mutations. We analysed pedigrees of the probands, and performed molecular screening in 65 relatives with the potential of carrying a GLA mutation. Five mutations (P40S, IVS4 ⁺⁴, G328V, R363H, R404del) were detected in seven unrelated Mexican families with the classic FD phenotype. Of the 65 relatives examined, 42 (64.6%) had a GLA gene mutation. In summary, among seven Mexican probands with FD, 65 relatives were at risk of carrying a known GLA mutation, and molecular screening identified 42 individuals with the mutation. Thus, our findings showed that it is important to perform molecular analysis in families with FD to detect mutations and to provide accurate diagnoses for individuals that could be affected.     

High European sauropod dinosaur diversity during Jurassic–Cretaceous transition in Riodeva (Teruel, Spain)

Abstract:  Up to now, more than 40 dinosaur sites have been found in the latest Jurassic – earliest Cretaceous sedimentary outcrops (Villar del Arzobispo Formation) of Riodeva (Iberian Range, Spain). Those already excavated, as well as other findings, provide a large and diverse number of sauropod remains, suggesting a great diversity for this group in the Iberian Peninsula during this time. Vertebrae and ischial remains from Riodevan site RD-13 are assigned to Turiasaurus riodevensis (a species described in RD-10, Barrihonda site), which is part of the Turiasauria clade. This is the first time that a taxon is attributed to Turiasaurus genus out of its type site. A Neosauropod caudal vertebra from the RD-11 site has been classified as Diplodocinae indet., supporting the previous attribution on an ilion also found in Riodeva (CPT-1074) referring to the Diplodocidae clade. New remains from the RD-28, RD-41 and RD-43 sites, of the same age, among which there are caudal vertebrae, are assigned to Macronaria. New sauropod footprints from the Villar del Arzobispo Formation complete the extraordinary sauropod record coming to light in the area. The inclusion of other sauropods from different contemporaneous exposures in Teruel within the Turiasauria clade adds new evidence of a great diversity of sauropods in Iberia during the Jurassic–Cretaceous transition. Turiasauria distribution contributes to the understanding of European and global palaeobiogeography.