Specific adhesion between pheochromocytoma (PC12) cells and adrenal medullary endothelial cells in co-culture

Summary Chromaffin cells in the adrenal medulla are found in close proximity to capillary endothelial cells, thereby forming the classical endocrine complex. To examine the possible chemical basis of their interaction in more detail, we have grown bovine adrenal medullary endothelial (BAME) cells in monolayer cultures and added to them pheochromocytoma (PC12) cells, a chromaffin tumor cell line of rats. The PC12 cells were chosen because of the similarities they share with adrenal medullary chromaffin cells. PC12 cells rapidly attached to BAME cells cultures, their rate of adhesion being significantly enhanced over binding of PC12 cells to either uncoated plates or to monolayers of unrelated cell cultures. Consistent with this observation, we noted that the extracellular matrix (ECM) derived from the BAME cells did not enhance PC12 cell adhesion and did not promote neurite sprouting as previously described for ECM derived from corneal endothelial cells. The specific adhesion between PC12 and BAME cells could be abolished by cell surface extracts derived from these two cells but not by extracts derived from unrelated cell types. This activity was heat-labile, sensitive to trypsin and, to a lesser extent, to neuraminidase. We therefore conclude that PC12 cells may interact with BAME cells by specific proteinaceous adhesive factors associated with their plasma membranes. These interactions might represent the formative role of cell-cell contacts in the organization of the developing adrenal gland.Abbreviations BAME bovine adrenal medullary endothelial cells - DMEM Dulbecco's modified essential medium - ECM extracellular matrix - EMEM Eagle's modified essential medium - FCS fetal calf serum - PBS phosphate-buffered saline - PC12 rat pheochromocytoma cells     

Temporal changes in the egglaying behaviour of the Hessian fly

Responses of mated female Hessian flies were investigated by analysing the behaviour of individual flies in wheat and oats. The behavioural repertoire of such females included: flying, alighting on leaves, arching of the body so that the tip of the abdomen touched the leaf surface, antennation, movements of the tip of the abdomen across the leaf at right angles to leaf veins, sitting with the ovipositor straight but still extended, and sitting with the ovipositor telescoped into the body. After alighting, females on wheat showed a higher frequency of transitions from arching to antennation and a lower frequency of transitions from arching to abdomen straight than females on oats. During the first 5 min of observations, individuals released into arenas with wheat arched and antennated 2–3 times more frequently than females released into oats. Time allotted to behaviours also differed; during the first 5 min, females in wheat spent 50 percent more time arching, whereas females in oats spent 50 percent more time sitting. Females in wheat also stayed longer and laid 4 times more eggs than females in oats. Temporal changes in egglaying were monitored by quantifying hourly rates of egglaying in no-choice assays for several hours following mating at 9:00 am. During the first and second hours post-mating, egglaying occurred infrequently. However, during the third hour post-mating (11:00 am to noon) females on wheat laid 5 times more eggs than females on oats. Rates of egglaying decreased on wheat but increased on oats during the fourth hour, and then during the fifth hour, decreased on both wheat and oats. Changes in egglaying responses were also evident when behaviours of individual females were measured 1–3 h vs. 3–7 h post-mating. Females deprived of host plants and released into wheat or oats later in the day showed higher frequencies of arching and antennation and laid more eggs before leaving the arena.

---

Résumé Les réactions de femelles préalablement accouplées de Mouches de Hesse ont été examinées en analysant le comportement de femelles isolées sur blé et sur avoine. Le répertoire comportemental de ces femelles comprenait: le vol, l'atterrissage sur feuille, la flexion du corps de sorte que l'extrémité de l'abdomen touchât la surface de la feuille, l'antennation, les mouvements de l'extrémité de l'abdomen sur la feuille à angle droit des nervures, le repos avec la tarière droite et encore dévaginée, le repos avec la tarière télescopée à l'intérieur du corps. Sur blé plus que sur avoine, les femelles après atterrissage ont présenté une fréquence plus élevée de passage de la flexion à l'antennation que de la flexion à l'abdomen droit. Durant les 5 premières minutes d'observation, les individus libérés dans des enceintes avec blé fléchirent et antennèrent 2 à 3 fois plus que ceux libérés sur avoine. Les durées des différentes séquences différaient aussi: sur blé, pendant les 5 premières minutes, les femelles passèrent plus de 50% du temps à fléchir, tandis que sur avoine elles passèrent plus de 50% du temps en repos. Les femelles restèrent aussi plus longtemps sur les feuilles de blé et y pondirent 4 fois plus d'oeufs que sur avoine.Les femelles de M. destructor ont montré une plasticité du seuil d'acceptation. Pendant les premières heures de ponte, elles ont été très sélectives et refusèrent, ou ne pondirent que quelques oeufs sur avoine, mais acceptèrent volontiers le blé. La discrimination s'est poursuivie tant que les femelles ont eu accès au blé en même temps qu'à l'avoine. Cependant, quand les femelles ont été privées de blé pendant plusieures heures, l'acceptation de l'avoine a augmenté. Cet accroissement de l'acceptation a eu lieu à peu près au moment où les femelles sur blé pondaient leurs derniers oeufs.

     

An improved method for light- and electron microscopial studies of nematode/fungal interactions

A method is presented that enables studies to be made of single nematode-fungal interactions under conditions where fungal growth at the expense of external nutrients is prevented. The nematophagous fungus Arthrobotrys ologospora was used as a model organism in these studies. The method is based on removal of the traps from the vegetative mycelium, immediately after a nematode was captured and transfer of the trap with the captured nematode into a droplet of sterile distilled water placed in a moisture chamber. In the absence of external nutrients, such isolated traps of A. oligospora were fully effective in penetrating and subsequently digesting the captured nematode. Solely vegetative mycelium was formed at the expense of the digested nematode; this developed from the trap that originally had captured the nematode. One advantage of the present method is that studies on various stages of the nematode-fungal interaction can now be performed under conditions that exclude major influences of external nutrients which otherwise could be communicated to the trap cells by way of the vegetative mycelium.     

Effect of anti-mosquito antibodies on the infectivity of the rodent malaria parasite Plasmodium berghei to Anopheles farauti

The effect of mouse anti-mosquito antibodies, present in the bloodmeal, on the infectivity of Plasmodium berghei Vincke to Anopheles farauti Laveran was investigated. Significantly fewer oocysts developed in mosquitoes feeding on mice immunized with sugar-fed mosquito midgut antigens than in mosquitoes feeding on control mice. Mosquitoes feeding on mice immunized with the midgut antigens derived from sugar-fed mosquitoes also showed reduced mortality and had lower infection rates than those fed on unimmunized mice. Blood-fed midgut antigen was less effective in producing these effects than sugar-fed midgut antigen.     

Underwater observations of piranhas in western Brazil

Synopsis The behaviour of three piranha species,Serrasalmus marginatus, S. spilopleura, andPygocentrus nattereri, and their prey fishes was studied underwater in the Pantanal region, Mato Grosso, Brazil. General habits, predatory tactics, feeding behaviour, and social interactions while foraging, as well as defensive tactics of prey fishes were observed.S. marginatus is solitary whereas the other two species live in shoals; their agonistic behaviour varies accordingly, the simplest being displayed by the solitary species. Predatory tactics and feeding behaviour also vary:S. spilopleura shows the most varied diet and highly opportunistic feeding strategy, which includes aggressive mimicry. The solitaryS. marginatus, besides fin and scale-eating, occasionally cleans larger individuals ofP. nattereri. Several cichlid species display defensive tactics clearly related to piranha attacks: tail protecting, watching, and confronting the predator are the most commonly observed behaviours. Piranhas seem to strongly influence use of habitat, social structure, and foraging mode of the fish communities.     

Conformational and helicoidal analysis of the molecular dynamics of proteins: "curves," dials and windows for a 50 psec dynamic trajectory of BPTI

A new procedure for the graphic analysis of molecular dynamics (MD) simulations on proteins is introduced, in which comprehensive visualization of results and pattern recognition is greatly facilitated. The method involves determining the conformational and helicoidal parameters for each structure entering the analysis via the method "Curves," developed for proteins by Sklenar, Etchebest, and Lavery (Proteins: Structure, Function Genet. 6:46-60, 1989) followed by a novel computer graphic display of the results. The graphic display is organized systematically using conformation wheels ("dials") for each torsional parameter and "windows" on the range values assumed by the linear and angular helicoidal parameters, and is present in a form isomorphous with the primary structure per se. The complete time evolution of dynamic structure can then be depicted in a set of four composite figures. Dynamic aspects of secondary and tertiary structure are also provided. The procedure is illustrated with an analysis of a 50 psec in vacuo simulation on the 58 residue protein, bovine pancreatic trypsin inhibitor (BPTI), in the vicinity of the local minimum on the energy surface corresponding to a high resolution crystal structure. The time evolution of 272 conformational and 788 helicoidal parameters for BPTI is analyzed. A number of interesting features can be discerned in the analysis, including the dynamic range of conformational and helicoidal motions, the dynamic extent of 2 degrees structure motifs, and the calculated fluctuations in the helix axis. This approach is expected to be useful for a critical analysis of the effects of various assumptions about force field parameters, truncation of potentials, solvation, and electrostatic effects, and can thus contribute to the development of more reliable simulation protocols for proteins. Extensions of the analysis to present differential changes in conformational and helicoidal parameters is expected to be valuable in MD studies of protein complexes with substrates, inhibitors, and effectors and in determining the nature of structural changes in protein-protein interactions.     

C1q,a collagen-like complement subcomponent,in dermatosparactic cattle: its extracellular modification is not affected by lack of procollagen N-terminal proteinase (pN-proteinase)

C1q, a collagen-like complement protein, was purified from the serum of a ddermatosparactic calf which lacks procollagen N-terminal proteinase (pN-proteinase). The specific hemolytic activity of the serum Clq from the dermatosparactic animal was identical to that of C1q from a normal calf. Gel-filtration of serum from dermatosparactic calf, on Sepharose 6B, showed the presence of C1q-antigenic material at only one position which was identical to the elution position of normal bovine C1q. No differdence, under dissociating conditions, could be seen in the size of the chains of C1q in specific immunoprecipitates isolated from the sera of dermatosparactic and normal animals, as judged by polyacrylamidegel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate (SDS). The C1q from the dermatosparactic animal showed the same N-terminal amino acid and typtic-digest peptide pattern on HPLC as C1q from the normal calf. These results strongly suggest that pN-proteinase is not involved in the extracellular processing of C1q.     

Promoters active in mammalian cells (pSV40) and in plants (pNOS) permit expression in yeast of the Tn5 APH(3') II gene

Abstract Four plasmids were constructed by associating Escherichia coli and yeast selection markers and replication origins to a structural gene coding for aminoglycoside phosphotransferase (APH(3')) controlled by different flanking sequences. We used the two bacterial genes of Tn5 (APH(3')II) and Tn903 (APH(3')I) as such and the chimeric pSVneo (APH(3')II) and pNOSneo (APH(3')II) constructs, functional in mammalian and plant cells, respectively. Yeast clones resistant to G418 were obtained with all plasmids except with that bearing the bacterial APH(3')II gene. The three plasmids harbouring the functional APH genes, however, conferred different levels of G418 resistance to yeast.     

Effects of selection criteria on yield stability in chickpea (Cicer arietinum L.)

Summary Selection in the F₃ generation for seed yield, fruiting branches/plant, effective pods/plant, and seed index (100-seed weight) was carried out in two chickpea crosses. Sixty F₅ lines (15 lines/selection criterion) along with check variety were evaluated for seed yield in three distinct environments. The effects of selection criteria on yield stability was examined using linear regression approach and genotype-grouping technique. There were no differences between selection criteria for linear yield responses of F₅ lines to different environments. Within all four selection criteria the lines showed similar linear responses. The non-linear component was relatively higher for lines selected for effective pods and seed index than lines selected for yield and fruiting branches. On the basis of mean yield and coefficient of variation across environments, the seed index was the least effective selection criterion for developing high yielding and stable lines. When the results of stability parameters and genotype-grouping technique were considered together, selection for yield and fruiting branches was highly effective for isolating stable and high yielding lines.