The peritrophic membrane in adult simuliids (Diptera) before and after feeding on blood and blood-sucrose mixtures

A peritrophic membrane formed in the posterior midgut of female simuliids of seven species within 30 min of feeding on blood of various avian or mammalian hosts, and 6–12 hr thereafter it displayed up to seven concentric laminae. Within the first 48 hr of blood digestion, the posterior part of the peritrophic membrane (where digestion was most advanced) began to decompose and PM disappearance was complete at the end of blood digestion. In different species blood digestion at 18°–20° required 120–180 hr which was increased to over 200 hr by microsporidan infection. If a blood-sucrose mixture went directly to the midgut, a thin membrane formed around it, but not if it went indirectly by way of the crop. A prefeeding secretion in the anterior midgut is considered to be the peritrophic membrane of the pharate adult surrounding a small, but variable, amount of material, the meconium.

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Résumé Sept espèces de simulies ont été étudiées: 5 ornithophiles, 2 mammalophiles. Trente minutes après un repas de sang sur divers oiseaux (poulet, canard) ou mammifères (homme, cerf, élan d'Amérique) on constate qu'une membrane péritrophique est sécrétée par toute le surface épithéliale dans la région moyenne de l'intestin moyen postérieur dilaté des femelles. Six à douze heures après le repas cette membrane comporte jusqu'à sept lamelles concentriques. Une sécrétion moins importante se forme autour de la petite quantité de sang que l'on trouve dans l'estomac antérieur, non dilaté et étroit; cette sécrétion glisse vers l'arrière et forme une capsule recouvrant le pôle antérieur du bol alimentaire sanguin dans la partie postérieure de l'intestin moyen, ceci pendant le premier jour. La digestion commence à la périphérie et à l'extrémité postérieure de la masse sanguine et se poursuit enfin à l'extrémité antérieure, où la membrane péritrophique conserve le plus longtemps sa structure en contact avec le sang non digéré. Dans les premières 48 heures de la digestion du sang, la région postértieure de la membrane péritrophique (là où la digestion est la plus avancée) commence à se décomposer, et sa disparition est complète quand la digestion du sang est achevée. Chez les différentes espèces étudiées, la digestion du sang à 18–20° exige 120–180 heures, pouvant demander plus de 200 heures chez des insectes atteints d'une infection par des microsporidies. Si un mélange de sang et sucrose parvient directement dans la région moyenne de l'intestin moyen, une membrane mince se forme autour, mais non si cet aliment passe par le jabot. Une sécrétion précédant l'alimentation s'observe dans l'intestin moyen antérieur des mouches non nourries et doit représenter, chez l'adulte venant d'éclore, la membrane péritrophique entourant le méconium: petite quantité de matière d'importance variable. Cette matière se retrouve souvent au centre de la masse sanguine après alimentation et est lente à digérer.

     

Steroidal saponins from Smilax lebrunii.

Two new steroidal saponins, (25 R)-spirostan-3 beta-ol-6-one-3-O-[alpha-L-arabinopyranosyl (1----6)]-beta-D-glucopyranoside and (25 R)-spirostan-3 beta-ol-6-one-3-O-[beta-D-glucopyranosyl(1---4)] [alpha-L-arabinopyranosyl(1----6)]-beta-glucopyranoside, were isolated from the rhizomes of Smilax lebrunii. Their structures have been established by chemical and spectral methods.     

Idiotypic analysis of anti-GAT antibodies. VII. Common idiotype on hybridoma antibodies to poly(Glu60 Ala40)

A single DBA/2 mouse, immunized with L-glutamic acid60-L-alanine40 (GA), was used to produce hybridoma cell lines. Seven hybridoma anti-GA antibodies were obtained for idiotypic analyses. Two hybridoma anti-L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) antibodies, preferentially reactive to GA, were studied in parallel. Anti-idiotypic antisera to purified anti-GAT and anti-GA serum antibodies and to hybridoma anti-GA antibodies were analyzed by idiotype binding and inhibition of idiotype binding assays. Five of the nine hybridoma antibodies exhibited common GA-1 idiotypic specificities previously demonstrated on the majority of anti-GA antibodies of inbred mouse strains of differing immunoglobulin heavy chain linkage groups; these hybridoma antibodies also possessed private idiotypic determinants. Two GA-1 negative hybridoma anti-GA antibodies appeared identical by immunochemical criteria, arguing that somatic hybridization does not artifactually generate private idiotypic determinants. The results demonstrate that the common GA-1 idiotype system is associated with a family of nonidentical but idiotypically related antibody molecules present in a single DBA/2 mouse, and these antibodies are part of the "GA-1 idiotypic family".     

On the carbon and sulphur metabolism in the meromictic Lake Faro (Sicily)

The processes of photosynthesis, chemosynthesis and sulphate reduction were quantitatively studied in the brackish meromitic lake Faro (Sicily) with the aid of C¹⁴ and S³⁵. The layer of “red water” was situated at the depht of the chemocline (13–14 m), where the average concentration of H₂S was 10 mg/l. The total biomass of bacterioplankton consisted in this layer mostly of a brown Chlorobium which reached a wet weight of 30 g/m³. The production of photosynthesis in this layer was 30–60 µg C/l/day. The microbial population in the “red water” was found adapted to an extremely low light intensity and to show a light optimum at the depth µg 9m where only 2,5% of outside light penetrates. The photoautotrophic microflora is consumed by infusoria found in mass in the “red water” layer. An active H₂S-production was found in the water column in the upper part of the H₂S-zone and in the bottom sediments. The data are discussed from the view point of the trophology of meromitic basins.     

How honeybee queen attendants become ordinary workers

Honeybee queen attendants disperse queen pheromones to supplement pheromone dispersal by direct queen-worker contacts. With time they lose their dispersal function exponentially due mainly to volatilization of queen pheromones carried on their bodies. The elimination of those airborne pheromones together with the air while ventilating the hive is balanced by pheromone release by the queen. This equilibrium results in a certain level of queen pheromones in the broodnest. The change of the pheromone level (for example, due to loss of the colony of its queen) can serve as a signal to alter the behaviour of the workers and the state of the colony.     

Use of perfluorocarbon emulsions in cell culture.

Perfluorocarbon emulsions were applied to hybridoma cultures grown in tissue culture tubes and column bioreactors. The oxygen transfer enhancement effect of perfluorocarbon emulsions was clearly demonstrated by the higher cell densities obtained in emulsion-supplemented systems. In addition, perfluorocarbon emulsions were shown to provide better cell suspension in a low-shear environment. The study in column bioreactors also suggested a cell protective effect of the employed perfluorocarbon emulsions in reducing the damage to cells by gas bubbles.     

Tumorigenic transformation of NIH 3T3 cells by the autocrine synthesis of transforming growth factor alpha

A variety of cancer cells overexpress transforming growth factor alpha (TGF alpha), a mitogenic peptide. A cDNA sequence coding for the full-length human TGF alpha precursor protein was subcloned into a retroviral expression vector and introduced into clone 7 NIH 3T3 cells, which have low numbers of endogenous epidermal growth factor receptors (EGFRs). The autocrine synthesis of TGF alpha by these cells resulted in their focal transformation. In contrast, control NIH 3T3 cells treated in a paracrine manner with exogenous, saturating concentrations of the mature form of TGF alpha, though stimulated to divide, remained morphologically untransformed. The addition of saturating quantities of soluble, mature TGF alpha to NIH 3T3 cells expressing the transferred TGF alpha gene actually suppressed their growth and focal transformation. The transformation induced by the TGF alpha gene remained an EGFR-dependent process, since the degree of transformation was correlated with EGFR expression in NIH 3T3 cells and since NR6 cells, which are Swiss 3T3 cells devoid of endogenous EGFRs, were transformed by the TGF alpha vector only when exogenous EGFR genes were also introduced. When inoculated into nude mice, the TGF alpha-expressing cells rapidly gave rise to tumors that grew progressively, whereas control cells did not form tumors. We conclude that in certain circumstances autocrine TGF alpha can be more oncogenic than paracrine and that paracrine TGF alpha can suppress this effect.     

An outcome model for human bladder cancer: A comprehensive study based on weighted gene co‐expression network analysis

The precision evaluation of prognosis is crucial for clinical treatment decision of bladder cancer (BCa). Therefore, establishing an effective prognostic model for BCa has significant clinical implications. We performed WGCNA and DEG screening to initially identify the candidate genes. The candidate genes were applied to construct a LASSO Cox regression analysis model. The effectiveness and accuracy of the prognostic model were tested by internal/external validation and pan‐cancer validation and time‐dependent ROC. Additionally, a nomogram based on the parameter selected from univariate and multivariate cox regression analysis was constructed. Eight genes were eventually screened out as progression‐related differentially expressed candidates in BCa. LASSO Cox regression analysis identified 3 genes to build up the outcome model in E‐MTAB‐4321 and the outcome model had good performance in predicting patient progress free survival of BCa patients in discovery and test set. Subsequently, another three datasets also have a good predictive value for BCa patients' OS and DFS. Time‐dependent ROC indicated an ideal predictive accuracy of the outcome model. Meanwhile, the nomogram showed a good performance and clinical utility. In addition, the prognostic model also exhibits good performance in pan‐cancer patients. Our outcome model was the first prognosis model for human bladder cancer progression prediction via integrative bioinformatics analysis, which may aid in clinical decision‐making.