The innervation of the pyloric region of the crab,Cancer borealis: Homologous muscles in decapod species are differently innervated

Summary The muscles of the pyloric region of the stomach of the crab,Cancer borealis, are innervated by motorneurons found in the stomatogastric ganglion (STG). Electrophysiological recording and stimulating techniques were used to study the detailed pattern of innervation of the pyloric region muscles. Although there are two Pyloric Dilator (PD) motorneurons in lobsters, previous work reported four PD motorneurons in the crab STG (Dando et al. 1974; Hermann 1979a, b). We now find that only two of the crab PD neurons innervate muscles homologous to those innervated by the PD neurons in the lobster,Panulirus interrruptus. The remaining two PD neurons innervate muscles that are innervated by pyloric (PY) neurons inP. interruptus. The innervation patterns of the Lateral Pyloric (LP), Ventricular Dilator (VD), Inferior Cardiac (IC), and PY neurons were also determined and compared with those previously reported in lobsters. Responses of the muscles of the pyloric region to the neurotransmitters, acetylcholine (ACh) and glutamate, were determined by application of exogenous cholinergic agonists and glutamate. The effect of the cholinergic antagonist, curare, on the amplitude of the excitatory junctional potentials (EJPs) evoked by stimulation of the pyloric motor nerves was measured. These experiments suggest that the differences in innervation pattern of the pyloric muscles seen in crab and lobsters are also associated with a change in the neurotransmitter active on these muscles. Possible implications of these findings for phylogenetic relations of decapod crustaceans and for the evolution of neural circuits are discussed.Abbreviations ACh acetylcholine - Carb carbamylcholine - cpv muscles of the cardio-pyloric valve - cpv7n nerve innervating muscle cpv7 - cv muscles of the ventral cardiac ossicles - cv1n nerve innervating muscle cvl - cv2n nerve innervating muscle cv2 - EJP excitatory junctional potential - IC inferior cardiac neuron - IV inferior ventricular neuron - IVN inferior ventricular nerve - LP lateral pyloric neuron - LPG lateral posterior gastric neuron - lvn lateral ventricular nerve - mvn medial ventricular nerve - p muscles of the pylorus - PD pyloric dilator neuron - PD _in intrinsic PD neuron - PD _ex extrinsic PD neuron - pdn pyloric dilator nerve - PY pyloric neuron - pyn pyloric nerve - STG stomatogastric ganglion - VD ventricular dilator neuron     

SOS induction by P1 Km miniplasmids.

We have constructed (in vitro) a set of P1 miniplasmids. The smallest of these that could function as an independent replicon contained the right side of EcoRI-5 plus all of EcoRI-8. Those miniplasmids that lack EcoRI-6 induce the SOS pathway of the cell as shown by (i) increased expression of the recA operon, (ii) excision of the cryptic genetic element e14, (iii) spontaneous induction of lambda, and (iv) dependence of e14 excision on recA+ function. This induction was contingent upon the replication of the P1 Km miniplasmids from their P1 origin and, thus, was apparently caused by an aberrant initiation of DNA replication. When P1 EcoRI-6 was present in cis or trans with a P1 Km miniplasmid, neither e14 nor lambda was excised, but the expression of the recA operon was still induced. These results suggest that P1 EcoRI fragments 5 and 8 are insufficient for normal replication, and thus our P1 Km miniplasmids induced SOS functions. A product of EcoRI-6 may partially restore normal replication.     

Investigation of the attachment of bovine corneal endothelial cells to collagens and other components of the subendothelium : Role of fibronectin

Bovine corneal endothelial cells adhered equally well to a variety of collagens (types I, III, IV and V) consistent with a role for fibronectin in this process. They did not exhibit a preferential binding to collagen type IV—as might be anticipated if laminin were to play a significant role in their adhesion. Inhibition studies with anti-fibronectin antibodies demonstrated the importance of endogenous fibronectin in the mediation of attachment. Consistent with this, binding did not appear to require the presence of exogenous protein, since cells bound to collagens equally well in the presence or absence of added fibronectin and binding was not stimulated by pretreatment of collagens with this protein.     

The Effect of mei-41 on Rdna Redundancy in DROSOPHILA MELANOGASTER

The recombination and repair defective mutant, mei-41, exhibits three rather striking effects on the genetic properties and chromosomal stability of rDNA in Drosophila. First, mei-41 inhibits rDNA magnification. However, mei-9, another recombination and repair defective mutation has no similar effect. This indicates that magnification requires some, but not all, of the gene products necessary for meiotic exchange. Second, under magnifying conditions, mei-41 induces interchanges between the X rDNA and either arm of the Ybb- chromosome. These interchanges occur at high frequency and are independent of rDNA orientation. Third, in mei-41 bb+/Ybb+ males, bobbed mutants in the X, but not the Y, also arise at high frequency. Evidence suggests that these events involve the rDNA type I insertion. The recombination and repair defective properties of mei-41 together with our results regarding its unusual and specific effects involving rDNA are explained in a simple model that has general implications for chromosome structure.     

Testosterone 5 alpha-reductase in rat brain

We describe a simple procedure for the microassay of testosterone 5 alpha-reductase in homogenates of rat brain. This enzyme converts testosterone to dihydrotestosterone. We have used this assay to characterize the enzymatic activity and to map its distribution. The apparent Km is 4.1 x 10(-6) M and the Vmax is 85.6 pmol/mg protein/h. The pH optimum is broad and extends from pH 6.0 to 8.0. For the brain regions surveyed, testosterone 5 alpha-reductase activity varied over a 10-fold range. The highest activities were observed in homogenates of the midbrain and pons (37-39 pmol/mg protein/h). The lowest were seen in homogenates of the thalamus, caudate nucleus, frontal cortex, hippocampus, hypothalamus, olfactory tubercle, and preoptic area (3-7 pmol/mg protein/h).     

Recognition of Leishmania donovani antigens by murine T lymphocyte lines and clones. Species cross-reactivity, functional correlates of cell-mediated immunity, and antigen characterization

Studies in man and experimental animals suggest that cell-mediated immunity is of primary importance in limiting the pathogenesis of cutaneous and visceral leishmaniasis. In an attempt to determine, more directly, the role of T lymphocytes and the nature of the antigens that activate them, we have propagated antigen-specific murine T lymphocyte lines and clones that proliferate in response to antigens present on the membrane of intact Leishmania donovani promastigotes. One such line cross-reacts with membrane antigens on seven other Leishmania species and, to a lesser extent, with antigens on African procyclic trypanosomes. T lymphocyte clones that also exhibited a broad range of species cross-reactivity were isolated. About 40% of these clones had highly restricted specificity, whereas 60% were more extensively cross-reactive. The parent line and some clones passively transferred footpad DTH when injected locally, and some secreted a lymphokine activity that elicited intracellular killing of amastigotes within infected macrophages. Although the proliferative response of most clones was H-2 restricted, two clones appeared to be reactive in the presence of allogeneic antigen presenting cells. The majority of the clones appeared to recognize carbohydrate containing antigens, and absorption with solid substrate-bound lectins indicated that these antigens contained both mannose and galactose ligands. The antigenic activity was also absorbed using either of two extensively cross-reactive anti-parasite monoclonal antibodies.