Intrinsic competition between the gregarious parasite,Cotesia glomeratus and the solitary parasite.Cotesia rubecula [Hymenoptera: Braconidae] for their host.Artogeia rapae [Lepidoptera: Pieridae]

The solitary endoparasite,Cotesia rubecula, was superior to the gregarious endoparasite,Cotesia glomeratus, in tests of intrinsic competition for their hostArtogeia rapae. When an egg ofC. rubecula was oviposited in the host prior to those ofC. glomeratus, C. rubecula always won the ensuing competition. When an egg ofC. rubecula was laid in the same host within 48 h after oviposition byC. glomeratus, C. rubecula was successful in more than 90% of the interactions. Even when the egg ofC. rubecula was oviposited in the same host 72 to 96 h after oviposition byC. glomeratus, C. rubecula won the competition approximately 33% of the time. The implications of intrinsic competition are discussed in relation to the establishment ofC. rubecula in an ecosystem containingA. rapae andC. glomeratus.      

A reinvestigation of the Gn-RH (gonadotrophin-releasing hormone) systems in the goldfish brain using antibodies to salmon Gn-RH

Summary The organization of Gn-RH systems in the brain of teleosts has been investigated previously by immunohistochemistry using antibodies against the mammalian decapeptide which differs from the teleostean factor. Here, we report the distribution of immunoreactive Gn-RH in the brain of goldfish using antibodies against synthetic teleost peptide.Immunoreactive structures are found along a column extending from the rostral olfactory bulbs to the pituitary stalk. Cell bodies are observed within the olfactory nerves and bulbs, along the ventromedial telencephalon, the ventrolateral preoptic area and the latero-basal hypothalamus. Large perikarya are detected in the dorsal midbrain tegmentum, immediately caudal to the posterior commissure. A prominent pathway was traced from the cells located in the olfactory nerves through the medial olfactory tract and along all the perikarya described above to the pituitary stalk. In the pituitary, projections are restricted to the proximal pars distalis. A second immunoreactive pathway ascends more dorsally in the telencephalon and arches to the periventricular regions of the diencephalon. Part of this pathway forms a periventricular network in the dorsal and posterior hypothalamus, whereas other projections continue caudally to the medulla oblongata and the spinal cord. Lesions of the ventral preoptic area demonstrate that most of the fibers detected in the pituitary originate from the preoptic region.     

Cadmium and zinc flux in wild-type and cadmium-resistant CHO cells

Cellular flux of cadmium-109 and zinc-65 is characterized in cultured Chinese hamster ovary cells. The transport of cadmium is primarily unidirectional and, following uptake, cadmium is strongly retained. Zinc transport is bidirectional and intracellular zinc continuously leaches out into the medium. Nonradioactive cadmium or zinc enhances the efflux of⁶⁵Zn from prelabeled cells. Transport of these metals into wild-type cells is not affected by azide, ouabain, cycloheximide, or actinomycin D. A cadmium-resistant mutant was isolated that exhibited altered sensitivities to certain inhibitors of macromolecular synthesis as well as quantitative differences in metal transport and accumulation. Although the mutant accumulates less cadmium than the wild-type cell, that which is retained is bound much more tightly. In addition, this lower rate of cadmium uptake is significantly decreased by either cycloheximide or actinomycin D. This suggests that thede novo synthesis of a protein or proteins is required for much of the net cadmium retention by the cadmium-resistant cells.     

Multiple chromatographic forms of ATP citrate lyase from rat liver.

ATP citrate lyase is shown to exist as multiple forms in extracts of rat liver. DEAE-Sephadex ion-exchange chromatography of liver supernatants reveals two peaks of activity. A minor, basic, component, comprising 14% of the recovered activity, is eluted without retention, whereas the major, acidic, form is eluted by a KCl gradient. Gel filtration of similar extracts shows the presence of a high-Mr form of ATP citrate lyase (Mr around 10(7) in addition to the tetrameric enzyme (Mr 4.1 X 10(5). This associated state, which represents 10% of the total activity, is unstable, breaking down to the tetramer, and appears to be disrupted by Mg2+. The basic form changes in the partially purified state to give the acidic form. Most of the high-Mr enzyme is acidic in nature. No evidence could be found for an association of the enzyme with mitochondrial or microsomal membranes. ATP citrate lyase from rat brain also shows two peaks of activity on DEAE-Sephadex ion-exchange chromatography, but the activity is distributed between the peaks in almost equal proportions. However, only the tetrameric enzyme was observed on gel filtration.     

Analysis of E1A-mediated growth regulation functions: binding of the 300-kilodalton cellular product correlates with E1A enhancer repression function and DNA synthesis-inducing activity.

Adenovirus E1A transforming function requires two distinct regions of the protein. Transforming activity is closely linked with the presence of a region designated conserved domain 2 and the ability of this region to bind the product of the cellular retinoblastoma tumor suppressor gene. We have investigated the biological properties of the second transforming region of E1A, which is located near the N terminus. Transformation-defective mutants containing deletions in the N terminus (deletion of residues between amino acids 2 and 36) were deficient in the ability to induce DNA synthesis and repress insulin enhancer-stimulated activity. The function of the N-terminal region correlated closely with binding of the 300-kilodalton E1A-associated protein and not with binding of the retinoblastoma protein. These results indicate that transformation by E1A is mediated by two functionally independent regions of the protein which interact with different specific cellular proteins and suggest that the 300-kilodalton E1A-associated protein plays a major role in E1A-mediated cell growth control mechanisms.     

Recurrent Hodgkin's disease in the breast. Diagnosis of a case by fine needle aspiration and immunocytochemistry

Recurrent Hodgkin's disease involving the breast in a 17-year-old girl was diagnosed by fine needle aspiration (FNA) biopsy of a solitary mass that developed one year after "curative" radiation. Benign breast disease and breast carcinoma were ruled out upon cytologic examination of the FNA smears, which contained diagnostic Reed-Sternberg cells and the characteristic polymorphic background elements. Follow-up immunoperoxidase staining for Leu-M1 on destained smears confirmed the diagnosis. Definitive therapeutic measures were initiated after the FNA diagnosis.     

A new and specific assay for ammonia and glutamine sensitive to 100 pmol.

A new enzymatic-radiochemical technique of NH₄⁺ determination has been developed that is sensitive and specific. The reaction of α-[1-¹⁴C]ketoglutarate with NH₄⁺ yields [1-¹⁴C]glutamate as a direct measure of the NH₄⁺ over a range of 0.1 to 10.0 nmol. By the measurement of the NH₄⁺ present in a sample before and after glutamine hydrolysis the assay also allows the determination of glutamine.     

Application of an optimized marker amplification protocol in immunohistochemistry — a valuable tool for visualizing antigenic sites of low signal strength or sparse distribution

Amplification of immunohistochemical markers received considerable attention during the 1980s and 1990s. The amplification approach was largely abandoned following the development of antigen retrieval and reporter amplification techniques, because the latter were incorporated more easily into high throughput automated procedures in industrial and diagnostic laboratories. There remain, however, a number of instances where marker amplification still has much to offer. Consequently, we examined experimentally the utility of an optimized marker amplification technique in diagnostically relevant tissue where either the original signal strength was low or positive sites were visible, but sparsely distributed. Marker amplification in the former case not only improved the visibility of existing positive sites, but also revealed additional sites that previously were undetectable. In the latter case, positive sites were rendered more intense and therefore more easily seen during low magnification examination of large areas of tissue.     

Purine Nucleoside Phosphorylase Deficiency: A Mutation Update

Purine nucleoside phosphorylase (PNPase) deficiency is an autosomal recessive disorder affecting purine degradation and salvage pathways. Clinically, patients typically present with severe immunodeficiency, neurological dysfunction, and autoimmunity. Biochemically, PNPase deficiency may be suspected in the presence of hypouricemia. We report biochemical and genetic data on a cohort of seven patients from six families identified as PNPase deficient. In all patients, inosine, deoxyinosine, guanosine, and deoxyguanosine were elevated in urine, and mutation analysis revealed seven different mutations of which three were novel. The mutation c.770A>G resulted in the substitution p.His257Arg. A second novel mutation c.257A>G (p.His86Arg) was identified in two siblings and a third novel mutation, c.199C>T (p.Arg67X), was found in a 2-year-old female with delayed motor milestones and recurrent respiratory infections. A review of the literature identified 67 cases of PNPase deficiency from 49 families, including the cases from our own laboratory. PNPase deficiency was confirmed in 30 patients by genotyping and 24 disease causing mutations, including the three novel mutations described in this paper, have been reported to date. In five of the seven patients, plasma uric acid was found to be within the pediatric normal range, suggesting that PNPase deficiency should not be ruled out in the absence of hypouricemia.