Sex attractants in nematodes

Nematodes communicate with each other using pheromones - chemicals secreted by one individual that affect the behaviour of others of the same species. Chemicals secreted into the environment are known to influence host location, dormancy (dauer-larva formation), competitive interactions and mate detection; they benefit the nematode by reducing energy expenditure on less orientated movements. Of these chemicals, sex pheromones associated with mate detection and attraction are of particular interest as potential biological control agents. Here, Barbara MacKinnon discusses these developments.     

Effects of serum amyloid A protein (SAA) on composition, size, and density of high density lipoproteins in subjects with myocardial infarction

The acute phase reactant serum amyloid A protein (SAA) circulates in plasma as a constituent of high density lipoproteins (HDL). Advantage has been taken of the induction of SAA in human subjects with myocardial infarction to study the effect of SAA on the physical and chemical properties of HDL. HDL were isolated by sequential ultracentrifugation and assayed for chemical composition. Apolipoprotein composition was assessed by SDS polyacrylamide gel electrophoresis. Size distribution of HDL was determined by gradient gel electrophoresis and density distribution by density gradient ultracentrifugation. In studies of 18 subjects with myocardial infarction, SAA accounted for 8-87% (median 52%) of the HDL apolipoprotein. These SAA-enriched HDL had a density comparable to that of normal HDL subfraction-3 (HDL3). Their chemical composition differed from normal HDL3, however, with a reduced phospholipid (17% vs 24%) and an increased triglyceride (7.7% vs 1.6%) value. When separated by gradient gel electrophoresis, the SAA-enriched HDL were much larger than normal HDL3, having a radius of 4.5-5.3 nm that extended well into the size range of HDL2; particle size correlated with SAA content. This disassociation between particle density and particle size was also observed with the SAA-enriched HDL isolated from a subject with secondary amyloidosis and also with normal HDL that had been enriched with SAA during incubation in vitro. Thus, the presence of high levels of SAA has been found to be associated with phospholipid-depleted particles of a density comparable to HDL3 but a size larger than normal HDL3.     

The role of primary bone grafting in complex craniomaxillofacial trauma

The role of craniofacial surgical techniques and immediate bone grafting in the management of complex craniofacial trauma has been reviewed. Four hundred and one patients with complex facial injuries have been treated. Two hundred and forty-one primary bone and cartilage grafts have been performed in 66 patients. Complex facial injuries should be managed by direct exposure, reduction, and fixation of all fractures utilizing interfragmentary wiring. Very comminuted or absent bone is replaced by immediate bone grafting, producing a stable skeleton without the need for external fixation devices. Associated mandibular fractures are managed with rigid internal fixation utilizing A-O technique. Results of immediate bone grafting have been excellent, and complications are rare. All deformities should be corrected, whenever possible, during the initial operation. This one-stage reconstruction of even the most complex facial injuries will prevent severe postoperative traumatic deformity and disability that may be extremely difficult or impossible to correct secondarily.     

Assessment of enzyme inhibition or stimulation in plasma membrane preparations

The purity of isolated plasma membranes is routinely judged by the activity of enzymes present both in this membrane and other locations in the cell. However, since enzyme inhibition and/or stimulation often occurs following disruption of the cell, the question as to which enzyme(s) provides a reliable marker of membrane purity should be considered. We have devised a simple method with which to address this problem. Inhibition or stimulation of plasma membrane marker enzymes can be rapidly assessed in cell homogenates and subfractions by mixing both samples, with known enzyme activity, and observing any deviation from the expected combined activity. Should the activity remain constant that enzyme can be used to gauge the purity of the plasma membrane preparation. Of the four putative plasma membrane marker enzymes examined only one, gamma-glutamyltranspeptidase appeared to give a reliable purity measurement in the cell system studied.     

Mapping Quantitative Trait Loci Controlling Milk Production in Dairy Cattle by Exploiting Progeny Testing

We have exploited ``progeny testing' to map quantitative trait loci (QTL) underlying the genetic variation of milk production in a selected dairy cattle population. A total of 1,518 sires, with progeny tests based on the milking performances of > 150,000 daughters jointly, was genotyped for 159 autosomal microsatellites bracketing 1645 centimorgan or approximately two thirds of the bovine genome. Using a maximum likelihood multilocus linkage analysis accounting for variance heterogeneity of the phenotypes, we identified five chromosomes giving very strong evidence (LOD score >/= 3) for the presence of a QTL controlling milk production: chromosomes 1, 6, 9, 10 and 20. These findings demonstrate that loci with considerable effects on milk production are still segregating in highly selected populations and pave the way toward marker-assisted selection in dairy cattle breeding.     

Early evolution of metazoan serine/threonine and tyrosine kinases: identification of selected kinases in marine sponges

The phylum Porifera (sponges) was the first to diverge from the common ancestor of the Metazoa. In this study, six cDNAs coding for protein- serine/threonine kinases (PS/TKs) are presented; they have been isolated from libraries obtained from the demosponges Geodia cydonium and Suberites domuncula and from the calcareous sponge Sycon raphanus. Sequence alignments of the catalytic domains revealed that two major families of PS/TK, the "conventional" (Ca(2+)-dependent) protein kinase C (PKC), the cPKC subfamily, as well as the "novel" (Ca(2+)- independent) PKC (nPKC), form two separate clusters. In each cluster, the sequence from S. raphanus diverges first. To approach the question about the origin of protein-tyrosine kinases (PTK), which are found only in Metazoa, we analyzed two additional PS/TKs which have been cloned from S. domuncula: the stress-responsive protein kinase (KRSvSD) and the protein-kinase-C-related kinase (PRKvSD). The construction of the phylogenetic tree, comprising the eight PS/TKs and the PTK cloned previously from G. cydonium, revealed that the PTK derived from the branch including the KRSvSD kinase. These data facilitate the first molecular approach to elucidate the origin of metazoan PTK within the PS/TK superfamily.      

Treatment of the painful neuroma by neuroma resection and muscle implantation

The successful treatment of the painful neuroma remains an elusive surgical goal. This report evaluates one approach to the management of this problem which entails neuroma excision and placement of the proximal end of the nerve away from denervated skin, away from tension, and into a well-vascularized environment: muscle. Seventy-eight neuromas in 60 patients with a mean follow-up of 31 months (range 18 to 43 months) were evaluated. Sixty-seven percent of these patients involved Workmen's Compensation and 57 percent had had at least one previous operation to treat their pain. The results demonstrated good to excellent results in 82 percent of the treated nerves in the entire group. Factors that were predictive of a poorer outcome were (1) digital neuroma (p less than 0.0005), (2) Workmen's Compensation (p less than 0.01), and (3) three or more previous operations for pain (p less than 0.01). Transposition of nerves into small superficial muscles or muscles with significant excursion resulted in treatment failures. The etiology and histopathology of treatment failures are reviewed. Treatment of radial sensory neuromas by transposition of the radial sensory nerve into the brachioradialis muscle when any associated injury to the lateral antebrachial cutaneous nerve was also treated, gave good to excellent relief of pain, and improved hand function in 88 percent of the patients.     

Regulation of rat ovarian cell growth and steroid secretion

A cultured rat ovarian cell line (31 A-F(2)) was used to study the effect of growth factors (epidermal growth factor [EGF] and fibroblast growth factor [FGF]), a survival factor (ovarian growth factor [OGF]), a hormone (insulin), and an iron-binding protein (transferring) on cell proliferation and steroid production under defined culture conditions. EGF and insulin were shown to be mitogenic (half-maximal response at 0.12 nM and 0.11 muM, respectively) for 31A-F(2) cells incubated in serum-free medium. EGF induced up to three doublings in the cell population, whereas insulin induced an average of one cell population doubling. FGF, OGF, and transferrin were found not to have any prominent effect on cell division when incubated individually with 31A-F(2) cells in serum-free medium. However, a combination of EGF, OGF, insulin, and transferrin stimulated cell division to the same approximate extent as cells incubated in the presence of 5 percent fetal calf serum. EGF or insulin did not significantly affect total cell cholesterol levels (relative to cells incubated in serum-free medium) when incubated individually with 31A-F(2) cells. However, cell cholesterol levels were increased by the addition of OGF (250 percent), FGF (370 percent), or a combination of insulin and EGF (320 percent). Progesterone secretion from 31A-F(2) cells was enhanced by EGF (25 percent), FGF (80 percent), and insulin (115 percent). However, the addition of a mitogenic mixture of EGF, OGF, insulin, and transferrin suppressed progesterone secretion 150 percent) below that of control cultures. These studies have permitted us to determine that EGF and insulin are mitogenic factors that are required for the growth of 31A-F(2) cells and that OGF and transferrin are positive cofactors that enhance growth. Also, additional data suggest that cholesterol and progesterone production in 31A-F(2) cells can be regulated by peptide growth factors and the hormone insulin.     

Electrophoretic migration of Paracoccidioides brasiliensis specific antigenic fraction

Using the technique of immunoelectroosmophoresisimmunodiffusion (IEOP-ID), two antigenic fractions of Paracoccidioides brasiliensis one of them species-specific, produced precipitin bands in both the cathodic and anodic zones. Reactions of complete identity among the bands formed in these zones were demonstrated by a modification of the technique, employing additional wells around the central antigen well. Such bands would correspond to a simple diffusion of the corresponding antigenic fractions rather than to active electrophoretic migration.

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Resumen Dos fracciones antigénicas de Paracoccidioides brasiliensis una de ellas presuntamente especifica, originan en la técnica de inmunoelectroosmoforesis-inmimodifusión (IEOF-ID), bandas de precipitación tanto en la región anódica como en la región catódica del preparado.Mediante simple procedimiento se demuestra reacción de identidad entre tales bandas cuyo origen correspondería a una difusión simple de las respectivas fracciones antigénicas sin movilidad electroforética activa.