Fibroblast growth factor signaling in Caenorhabditis elegans.

Growth factor receptor tyrosine kinases (RTKs), such as the fibroblast growth factor receptor (FGFR), play a major role in how cells communicate with their environment. FGFR signaling is crucial for normal development, and its misregulation in humans has been linked to developmental abnormalities and cancer. The precise molecular mechanisms by which FGFRs transduce extracellular signals to effect specific biologic responses is an area of intense research. Genetic analyses in model organisms have played a central role in our evolving understanding of these signal transduction cascades. Genetic studies in the nematode C. elegans have contributed to our knowledge of FGFR signaling by identifying genes involved in FGFR signal transduction and linking their gene products together into signaling modules. This review will describe FGFR-mediated signal transduction in C. elegans and focus on how these studies have contributed to our understanding of how FGFRs orchestrate the assembly of intracellular signaling pathways.     

Accumulation of CK-MM is impaired in innervated and contracting cultured muscle fibers of Duchenne muscular dystrophy patients

No specific abnormalities have been reproducibly manifested in aneurally cultured muscle of Duchenne muscular dystrophy (DMD) patients. We now report that the accumulation of the muscle-"specific" isozyme of creatine kinase (CK-MM) was significantly and preferentially impaired in long-term innervated contracting muscle fibers cultured from 4 DMD patients (DMD-InnCMFs) compared to: i) their noninnervated sister-cultured muscle fibers, and ii) innervated contracting control cultured human muscle fibers (Control-InnCHMFs). Accumulation of other muscle-"specific" isozymes (MSIs), viz. glycogen phosphorylase, phosphoglycerate mutase, and lactic dehydrogenase, was not significantly impaired. We have not observed preferentially-impaired CK-MM accumulation in any Control-InnCHMFs from 22 patients (children and adults) with a variety of neuromuscular diseases. There was no apparent difference between DMD-InnCMFs and Control InnCHMFs regarding: acceptance of innervation; neuronally-driven, virtually continuous muscle-fiber contractions; characteristic myofiber organization by phase-contrast microscopy, and increased longevity of the innervated fibers.     

Evaluation of N2-fixation and nitrogen economy of a maize/cowpea intercrop system using15N dilution methods

Yields of above ground biomass and total N were determined in summer-grown maize and cowpea as sole crops or intercrops, with or without supplementary N fertilizer (25 kg N ha⁻¹, urea) at an irrigated site in Waroona, Western Australia over the period 1982–1985. Good agreement was obtained between estimates of N₂ fixation of sole or intercrop cowpea (1984/85 season) based on the¹⁵N natural abundance and¹⁵N fertilizer dilution techniques, both in the field and in a glasshouse pot study. Field-grown cowpea was estimated to have received 53–69% of its N supply from N₂-fixation, with N₂-fixation onlyslightly affected by intercropping or N fertilizer application. Proportional reliance on N₂-fixation of cowpea in glasshouse culture was lower (36–66%) than in the field study and more affected by applied N. Budgets for N were drawn up for the field intercrops, based on above-ground seed yields, return of crop residues, inputs of fixed N and fertilizer N. No account was taken of possible losses of N through volatilization, denitrification and leaching or gains of N in the soil from root biomass. N₂-fixation was estimated tobe 59 kg N ha⁻¹ in the plots receiving no fertilizer N, and 73 kg N ha⁻¹ in plots receiving 25 kg N ha⁻¹ as urea. Comparable fixation by sole cowpea was higher (87 and 82 kg N ha⁻¹ respectively) but this advantage was outweighed by greater land use efficiency by the intercrop than sole crops.     

Die Entwicklung der Laut?u?erungen bei der Graugans (Anser anser)

Zusammenfassung Das Lautrepertoire von sechs handaufgezogenen Graugänsen wurde in individuellen Längsschnitten vom Schlüpfen bis zum Alter von 100 Tagen mit sonagraphischer Methode analysiert. Die Einteilung des Repertoires erfolgte nach drei verschiedenen Kriterien: Klang, Sonagramm und Kontext. Im jugendlichen Repertoire ließen sich 4 Rufklassen voneinander trennen. Im Laufe der Jugendentwicklung veränderten sich vor allem die phonetischen Parameter der Rufe, während die syntaktischen weitgehend konstant blieben. Nach einem Anstieg in der ersten Woche fiel die Tonhöhe der Rufe bei allen untersuchten Individuen und Rufklassen gleichmäßig ab. Der Stimmbruch, meßbar an der Zunahme geräuschhafter Komponenten, war ein kontinuierlicher, langfristiger Prozeß. Die Individualität war nicht in einem einzelnen, wohl aber in der Kombination mehrerer Merkmale faßbar. Die Geschlechter waren schon früh an Unterschieden in der Tonhöhe erkennbar. An sonstigen ontogenetischen Veränderungen innerhalb des Untersuchungszeitraumes konnten die Erweiterung des Repertories durch Aufspaltung und Reifung sowie ein möglicher Verlust von Rufklassen beobachtet werden.

---

Juvenile development of vocalizations in Greylag Geese (Anser anser)

Summary The juvenile vocal development of six Greylag Geese from hatching up to the age of 100 days was analysed by using sonagraphic methods. The calls were classified by means of the acoustic phenomenon, sonagrams, and context criteria. The juvenile repertoire included four main call types. During ontogeny, changes of call parameters mainly referred to phonetic characteristics, whereas syntactic parameters remained more or less constant. The frequency pitch of calls changed to higher levels during the first week of development while in older goslings this parameter decreased constantly. This held true for each individual and call type. Breaking of the voice, defined as an increment of noisy parts in the vocalizations, is described as a continuous long term process. Structural individuality of calls apparently was not based on one single parameter, but on the combination of several ones. Sex differences were found in the pitch of vocalizations, correlating with different body weights of male and female geese. Additional developmental processes of the vocal repertoire included differentiation, maturation of new call types, and apparent suppression of juvenile ones. The functional organization of the juvenile call system in Greylags is discussed.

---

---

Herrn Dr. Hans Löhrl zum 75. Geburtstag gewidmet     

Detergent solubilization of the interleukin 1 receptor

Interleukin 1 (IL 1) receptors were solubilized from membranes prepared from murine EL-4 thymoma cells with the zwitterionic detergent 3[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS). Binding of IL 1 to the solubilized receptor was detected by a polyethylene glycol (PEG) precipitation procedure. Concentrations of CHAPS from 4 to 8 mM were effective in solubilizing the IL 1 receptor. At 10 mM CHAPS, there was some loss in binding activity, whereas 2 mM CHAPS was completely ineffective in solubilizing the receptor. Detergent concentrations of 4 mM were routinely used. The solubilized receptor retains the ability to bind 125I-IL 1 in a specific and saturable manner. Scatchard analysis reveals a single type of high affinity binding site having an apparent dissociation constant (KD) of approximately 1.2 X 10(-10) M. Nearly identical KD values are observed for membrane fractions. There are approximately 400 to 500 fmol receptor/mg protein in the detergent extract, corresponding to a two- to threefold enrichment in the Bmax observed for membranes. There is no loss in receptor activity as determined by complete recovery of the total number of binding sites from membranes after solubilization. Binding kinetics show that apparent steady state for the solubilized receptor is reached after 60 min at 37 degrees C. The binding of 125I-IL 1 is essentially irreversible because relatively little bound ligand can be dissociated from the receptor on the addition of excess unlabeled IL 1 at 37 degrees C. Both human IL 1 alpha and IL 1 beta compete for binding of 125I-IL 1 to the soluble receptor, confirming that IL 1 alpha and IL 1 beta bind to the same receptor. Other recombinant proteins, including interferon-alpha A, interferon-gamma, and interleukin 2 have no inhibitory effect.     

Class I-like MHC molecules expressed by baboon placental syncytiotrophoblast

Human placental villous trophoblast is known to be unreactive with W6/32 and other monoclonal antibodies recognizing monomorphic determinants of human class I MHC heavy chains, whereas extravillous cytotrophoblast in the placental bed is W6/32-reactive by immunohistology. We have now demonstrated, in contrast, that syncytiotrophoblast is the only cellular component of baboon early placental villous tissue which is reactive with any of these antibodies. Radioimmunoprecipitation of detergent-solubilized baboon placental membrane preparations, and subsequent SDS-PAGE, has shown the W6/32-reactive component to have an m.w. of 41,000 and to be associated with beta 2-microglobulin, whereas baboon peripheral lymphocytes express 45,000 m.w. W6/32-reactive antigens comparable with the HLA-A,B,C heavy chains of human lymphocytes.