Comparing different methods for trapping mated queens of weaver ants (Oecophylla longinoda; Hymenoptera: Formicidae)

The predatory efficiency of African weaver ants Oecophylla longinoda and their utilisation in protein production is a function of ant abundance. Reliable control of insect pests in tropical crops is achieved when ant populations are constantly high. Transplanted populations of weaver ant colonies containing egg-laying queens are more stable than those without. Achieving such stability through collection of colonies established in the wild is usually difficult because of uncertainty in locating the nest containing the egg-laying queen. In this study, we investigated four methods that may be used to collect mated queens that subsequently can be used to stock ant nurseries. The catch efficiencies of (1) leaf traps, (2) paper traps (both types providing a refuge for founding queens), (3) random search for queens and (4) light trapping were compared. Light trapping was the most efficient way to collect queens followed by leaf traps, random search and, last, paper traps. Light trapping and random search, though, required the presence of a person throughout the ant's mating season (several months), whereas this was not required when using leaf and paper traps.     

Ligation of Major Histocompatability Complex (MHC) Class I Molecules on Human T Cells Induces Cell Death through PI-3 Kinase–induced c-Jun NH2-terminal Kinase Activity: A Novel Apoptotic Pathway Distinct from Fas-induced Apoptosis

Ligation of major histocompatability complex class I (MHC-I) molecules expressed on T cells leads to both growth arrest and apoptosis. The aim of the current study was to investigate the intracellular signal pathways that mediate these effects.MHC-I ligation of human Jurkat T cells induced a morphologically distinct form of apoptosis within 6 h. A specific caspase inhibitor, which inhibited Fas-induced apoptosis, did not affect apoptosis induced by MHC-I ligation. Furthermore, MHC-I–induced apoptosis did not involve cleavage and activation of the poly(ADP- ribose) polymerase (PARP) endonuclease or degradation of genomic DNA into the typical fragmentation ladder, both prominent events of Fas-induced apoptosis. These results suggest that MHC-I ligation of Jurkat T cells induce apoptosis through a signal pathway distinct from the Fas molecule.In our search for other signal pathways leading to apoptosis, we found that the regulatory 85-kD subunit of the phosphoinositide-3 kinase (PI-3) kinase was tyrosine phosphorylated after ligation of MHC-I and the PI-3 kinase inhibitor wortmannin selectively blocked MHC-I–, but not Fas-induced, apoptosis. As the c-Jun NH₂-terminal kinase (JNK) can be activated by PI-3 kinase activity, and has been shown to be involved in apoptosis of lymphocytes, we examined JNK activation after MHC-I ligation. Strong JNK activity was observed after MHC-I ligation and the activity was completely blocked by wortmannin. Inhibition of JNK activity, by transfecting cells with a dominant-negative JNKK– MKK4 construct, led to a strong reduction of apoptosis after MHC-I ligation. These results suggest a critical engagement of PI-3 kinase–induced JNK activity in apoptosis induced by MHC-I ligation.Apoptosis is an active form of cell death associated with certain characteristic morphological changes of the cell. These include cell shrinkage, condensation of chromatin, and usually, but not always, fragmentation of genomic DNA into specific oligonucleosomal fragments, also referred to as apoptotic DNA ladder (21). In addition, a morphologically distinct form of apoptosis has been described in germinal centers, thymocyte suspensions, and certain tumors with characteristic features of type B dark cells (7, 34). The condensed chromatin in these cells is not smoothly redistributed into the characteristic eye seen in the nucleus of classical apoptosis; the cytoplasm is darkened and the mitochondria and endoplasmatic reticulum tend to be swollen (7, 34).The mammalian interleukin-1β–convertase enzyme (ICE)¹ protease family (caspases) are known to be critically involved in Fas- and tumor necrosis factor α–induced apoptosis (12). All caspases share two features: (a) they are synthesized as proenzymes and they are activated by cleavage at specific aspartate residues, and (b) both have the same consensus sequence as their own protease activity (14). Thus, the caspases are presumed to be regulated within a hierarchy of auto- and trans-cleavage. In Fas- mediated apoptosis, a sequential activation of caspase 1 (ICE) and caspase 3 (CPP32) has been demonstrated (13). Recent evidence suggests that one subfamily of caspases (inhibitable by YVAD pseudo-substrate) works proximally in Fas-induced apoptosis, leading to release of cytochrome C and other factors from the mitochondria. The initially activated caspases, together with the released factors from the mitochondria, activate the effector caspases (inhibitable by DEVD pseudo-substrate) by a mechanism that is not well defined (22). One of the targets of the effector caspases is the nuclear enzyme poly(ADP-ribose) polymerase (PARP) involved in DNA damage sensing. PARP activity is thought to be critical for apoptosis induced through caspase 3 (5, 43). The PARP enzyme is a 116-kD protein that is cleaved into a 85-kD fragment upon activation (43).Aurintricarboxylic acid (ATA), an inhibitor of Ca²⁺- dependent endonuclease activity (23, 29), has been shown to inhibit apoptosis that occurs without DNA fragmentation (25, 32). The mechanism by which ATA inhibits apoptosis is not fully understood. However, inhibition of endonuclease activity may not be the only function of ATA; rather, inhibition of topoisomerase II that induces chromatin condensation during apoptosis seems to be important (6). ATA has also been shown to inhibit the Ca²⁺-activated enzyme calpain, which may be involved in apoptosis (33).A new member of the mitogen-activated protein kinase (MAPK) superfamily designated c-Jun NH₂-terminal kinase (JNK), has recently been identified (16). A signal pathway functionally independent from extracellular signal-regulated kinase (ERK), which involves JNKK–MKK4, activates JNK (11, 49, 52). JNK is activated by dual phosphorylation of a Thr-Pro-Tyr motif during apoptosis induced by UV light, heat shock, and ligation of the Fas antigen (8, 17, 45, 50). Costimulation of T cells with T cell antigen receptor complex (TCR–CD3) and CD28 ligation, or CD40 ligation of B cells also results in activation of JNK (36, 41). Thus, JNK activity is involved in processes leading to both cell death and differentiation/activation. It has been demonstrated that apoptosis can be regulated through a balance between members of the MAPK superfamily; e.g., high JNK and low ERK activities may lead to apoptosis, whereas high JNK and ERK activities prevent apoptosis (17, 51).Stimulation of T cells through the major histocompatability complex class I (MHC-I) molecule initiates a cascade of biochemical changes that can lead to either activation and growth or cell cycle arrest and apoptosis (1, 4, 31, 40, 44). One of the critical events that occurs in both cases is the activation of tyrosine kinases, resulting in tyrosine phosphorylation of a variety of proteins including phospholipase C-γ1 (PLC-γ1) and ZAP70 (38, 39). We have recently shown that tyrosine kinase activity appears to be critical for growth inhibition and apoptosis induced by ligation of MHC-I molecules (4, 38). The functional outcome of MHC-I ligation is tightly linked to regulation of peripheral T cell activity and tolerance induction (37, 42).In the present study we have investigated the intracellular signal pathway leading to apoptosis after MHC-I ligation of T cells, in an attempt to find a cause-and-effect relationship between the biochemical and functional consequences of MHC-I ligation. We present evidence that MHC-I induces apoptosis through a distinct pathway involving phosphoinositide-3 (PI-3) kinase–induced JNK activity.     

Steroid metabolism in the hormone dependent MCF-7 human breast carcinoma cell line and its two hormone resistant subpopulations MCF-7/LCC1 and MCF-7/LCC2

Androgen and estrogen metabolism was investigated in the hormone-dependent human breast cancer cell line MCF-7 and its two hormone-resistant sublines MCF-7/LCC1 and MCF-7/LCC2. Using the product isolation method, the activity of aromatase, 5-reductase, 3/β-hydroxysteroid oxidoreductase and 17β-hydroxysteroid oxidoreductase were investigated isolating the following steroids: estriol (E₃), estradiol (E₂), estrone (E₁), 3/β-androstanediol (A-diol), testosterone (T), dihydrotestosterone (DHT), androsterone (AND), androstenedion (4-AD) and androstanedione (A-dion). For all experiments, cells were preincubated with cortisol and subsequently incubated with [¹⁴C]T or [¹⁴C]4-AD as the substrate in medium without phenol red and with serum charcoal stripped of steroids. The results showed no aromatase activity in any of the cell lines under the experimental conditions used, and preincubation with cortisol had no effect on the enzyme activity. With [¹⁴C]T as the substrate, the metabolized level of DHT was very similar in the three cell lines, though MCF-7/LCC1 and MCF-7/LCC2 utilized the substrate to a much lesser extent. The amount of DHT and 4-AD produced were comparable in the two hormone-resistant cell lines, while the amount of 4-AD was significantly higher in MCF-7 cells. No differences in enzyme activity were found in the three cell lines when [¹⁴C]4-AD was used as the substrate. This study showed an altered androgen metabolism in the MCF-7/LCC1 and MCF-7/LCC2 sublines compared to the parent MCF-7. However, since treatment with DHT and T inhibited cell growth equally well in all three tumor cell lines, it is unlikely that the found differences in steroid metabolism was involved in the acquisition of the endocrine resistance of the two MCF-7 sublines.     

Mouse embryonic fibroblasts derived from Odin deficient mice display a hyperproliiferative phenotype.

Odin is a recently identified cytosolic phosphotyrosine binding (PTB) domain containing negative regulatory protein, that was discovered on the basis of its ability to undergo tyrosine phosphorylation upon stimulation by epidermal growth factor in HeLa cells. The protein was originally obtained as a KIAA clone (KIAA 0229) from the Kazusa DNA Research Institute which maintains the HUGE protein database--a database devoted to the analysis of long cDNA clones encoding large proteins (>50 kDa). Odin has been demonstrated to cause downregulation of c-Fos promoter activity and to inhibit PDGF-induced mitogenesis in cell lines. To further investigate the role of Odin in growth factor receptor signaling and to elucidate its biological function in vivo, we have generated mice deficient in Odin by gene targeting. Odin-deficient mice do not display any obvious phenotype, and histological examination of the kidney, lung and liver does not show any major abnormalities as compared to wild-type controls. However, mouse embryonic fibroblasts (MEFs) generated from Odin-deficient mice exhibit a hyperproliferative phenotype compared to wild-type-derived MEFs, consistent with its role as a negative regulator of growth factor receptor signaling. Our results confirm that although Odin expression in mice is not essential for any major developmental pathway, it could play a significant functional role to negatively regulate growth factor receptor signaling pathways.     

Gastric bypass surgery reveals independency of obesity and diabetes melitus type 2

Background

Roux-en-Y gastric bypass surgery is widely applied to ameliorate morbid obesity, including diabetes in people with type 2 diabetes. The latter vanish a few days after surgery for many, but not in all patients before any weight reduction has occurred. The explanation for this change in metabolic status is poorly understood, but the observation may suggest that the fate obesity and diabetes is only partly linked after surgery.

Methods

The trajectories of weight reduction measured as reduced body mass index (BMI) in 741obese subjects with and without diabetes were evaluated. Evaluation was performed on three groups: 1) subjects that were non-diabetic before and after surgery; 2) subjects that were diabetics before surgery but non-diabetics after surgery; and 3) subjects that were diabetics before surgery and remained diabetics after surgery. The diabetic state was established at HbA1c above 48 mmol/mol.

Results

The trajectories differ significantly between groups and any sub-populations of groups, the latter identified by the distance between individual trajectories using a k-means procedure. The results suggest that different domains in the enormous genetic network governing basic metabolism are perturbed in obesity and diabetes, and in fact some of the patients are affected by two distinct diseases: obesity and diabetes mellitus type 2.

Conclusion

Although RYGB “normalized” many glycaemic parameters in some of the diabetic subjects apparently converting to a non-diabetics state, other diabetic subjects stay diabetic in the context of the new gut anatomy after surgery. Thus, the obesity part of the glycaemic derangement may have been ameliorated, but some defects of the diabetic state had not.

     

Temporal changes in pollen flow and neighbourhood structure in a population of Saxifraga hirculus L.

Summary The population are of flowering shoots of the perennial herb, Saxifraga hirculus, reaches a max. of 134 m² and an overall density of flowers/m² of 11.4. The flower is mainly visited by a syrphid sp., Eurimyia lineata, and to a lesser extent by another syrphid Neoscia tenur, a moth, Zygaena trifolii, and a fungus gnat, Asindulum nigrum. The distribution of the interfloral flight distance is leptokurtic. The mean flight distance of the visitors is 101 cm. 10% of the flights are much longer (2–8 m: cross-flower patch, and about 20 m: cross-population flights). If they are not included, the mean of flights (<1.7 m) becomes 28 cm. These flights become shorter with increasing flower density. The visitors do not have a nearest-neighbour foraging pattern. They visit on average the 8th nearest neighbour. The distribution of flight directions is uniform. Seed dispersal distances have a leptokurtic distribution and a mean dispersal distance of 13 cm. The ecological neighbourhood area is 66.4 m² and 64.9 m² assuming normality and allowing for leptokurtosis. Z. trifolii with its large proportion of long flights increases the size of the neighbourhood area considerably. The mean flight distance (<1.7 m) is correlated with neighbourhood area. The evolutionary impact of moths and butterflies to plant population structure is stressed.     

Serum-γ-Glutamyltranspeptidase (γ-GT) and Aspartate-Aminotransferase (AspAT) Activities in Adult Cattle with Chronic Fasciola Hepatica Infection

Sera from adult cattle with fluke-infected and normal livers were analyzed for γ-GT and AspAT activities. The analyses revealed no significant increases in either γ-GT or AspAT values of the animals with fascioliasis as compared with the non-infected animals. The advanced chronic stage of the infection characterized by hepatic fibrosis, limited injury of parenchyma and low fluke burdens may explain the lack of enzymatic increase.     

Incidence of Anticonvulsant Osteomalacia and Effect of Vitamin D: Controlled Therapeutic Trial

The bone mineral content (B.M.C.) in both forearms (related to total body calcium) was measured by photon absorptiometry for a controlled therapeutic trial in a representative sample of epileptic outpatients, comprising 226 patients treated with one or two major anticonvulsant drugs (phenytoin, phenobarbitone, primidone).Initially the mean B.M.C. value for all epileptic patients was 87% of normal. During treatment with 2,000 international units of vitamin D₂ daily for three months an average B.M.C. increase of 4% was found, whereas the B.M.C. values remained unchanged in the placebo group and in the control groups. The incidence of hypocalcaemia and raised serum alkaline phosphatase was 12% and 43% respectively. The biochemical indices of osteomalacia were related to B.M.C. These results indicate that epileptic patients should be closely supervised for the occurrence of anticonvulsant osteomalacia, and, possibly, receive prophylactic treatment with vitamin D.