Yeast derivatives and wheat germ in the adult diet modulates fecundity in a tephritid pest.

Anastrepha fraterculus (Wiedemann), a pest of great economic importance in South America, needs urgently to be controlled by environmentally friendly methods such as the sterile insect technique for which mass rearing of insects is required. Because oogenesis takes place during the adult stage, mass-rearing facilities should provide the females a diet that maximizes egg production at the lowest cost. Accordingly, we investigated the effect of artificial protein sources in the adult diet (yeast derivatives of different cost but with similar amino acids profiles, and the addition of wheat germ) on fecundity. Additionally, we evaluated different ratios of yeast derivatives or wheat germ on ovary maturation, fecundity, and fertility as well as their association with the nutrient content of females. Females fed hydrolyzed yeast and yeast extract attained the highest fecundity level, and those fed brewer's yeast the lowest. Reducing the amount of hydrolyzed yeast, an expensive protein source, in the diet negatively affected fecundity and ovary maturation. Increasing the amount of brewer's yeast, a low-cost protein source, did not favor fecundity. The addition of wheat germ in the adult diet improved fecundity regardless of the yeast derivate considered. Percentage of egg hatch was not affected by the diet. Nutrient content of A. fraterculus females varied according to the adult diet provided and mating status. Our findings provide novel baseline information to understand the role of nutrition on reproductive performance of A. fraterculus females and are discussed in the context of resource allocation. They also provide valuable advances in the search for cost-effective adult diets at fruit fly mass rearing facilities.

The use of tetracycline hydrochloride as a rapid fluorescent stain for myelin membranes in vertebrates and invertebrates.

We report here the use of tetracycline as a fast and reliable histological stain of myelinated nerves. These results are significant in that they point to tetracyclines as potentially important probes to study the role of divalent and trivalent cations in myelinated nerves. The usefulness and specificity of tetracycline as a supravital probe for calcium and iron metabolism in myelinated nerves is currently under study.

Development of myelinated and unmyelinated fibers of human vagus nerve during the first year of life.

As an important component of cardiorespiratory control, the vagus nerve and its maturation were evaluated in normal infants in order to provide standards of comparison with infants with dysfunctional neural control mechanisms. Myelinated and unmyelinated fibers in the cervical vagus nerve were examined in 27 term infants. Number of fibers, axon diameters, and myelin thickness were compared among four age groups. The histograms of axon size exhibited a skewed distribution that persisted during the age range examined for both myelinated and unmyelinated vagus fibers. Fiber size distributions of myelinated fibers, however, already showed an incipient multimodal distribution after 3 months. No major increase was observed in the average axon size of myelinated and unmyelinated fibers. A significant increase was observed, however, in the average content of myelin in myelinated fibers expressed as myelin thickness, number of lamellae or g ratio (internal/external diameter). These results suggest an active myelination during the first 9 months of life without a major change in the axonal characteristics of the fibers. A marginal increase in the density of myelinated fibers with age, both in terms of total number and the relation to unmyelinated fibers, suggests a slow transition from unmyelinated to myelinated fibers during the first year of life, particularly during the first 3 months. The present morphometric parameters indicate an active deposition of myelin before the maturation of cross-axonal dimensions. The distribution of g ratios also suggests that optimal conduction velocity is compromised only in a fraction of all vagal myelinated fibers.

The development of the diaphragm in infants with sudden infant death syndrome.

The morphological development of the skeletal muscle of the diaphragm was studied in normal controls and cases of sudden infant death syndrome (SIDS). Measurements of fiber diameter indicated that the SIDS population had significantly larger diameters for type 1 and type 2 fibers than the control population. The ratio of type 1 to type 2 fibers was found to remain significantly depressed with increasing age in the SIDS population compared with the control population, where it increased linearly to values between 0.8 and 1.2 after 10 months of age. These results suggest an abnormality in the development of the diaphragm of SIDS victims, although its exact nature remains to be determined.

Isolation and initial characterization of myelin-like membrane fractions from the nerve cord of earthworms (Lumbricus terrestris L).

We report here the isolation of fractions enriched in components of the myelin-like membranes surrounding the giant axons of the earthworm. Lumbricus terrestris L. The composition and purity of the fractions have been assessed using SDS-protein electrophoresis, Western immunoblots, and electron microscopy. Preliminary enzyme assays indicated that the mitochondrial marker, succinate dehydrogenase, has a similar specific activity distribution in earthworm nerve cord and in mouse liver sedimentation velocity fractions, however, the distribution of the total units of activity among the fractions seems to indicate the existence of smaller mitochondria in earthworm nerve cord compared with mouse liver mitochondria. In earthworm nerve cord fractions, Na+/K+ ATPase and Ca2+/Mg2+ ATPase were found to be enriched exclusively in the fraction containing large plasma and myelin-like membranes, while in the mouse liver fractions, the total units of these two enzymes were found to be distributed broadly among fractions. 5'-Nucleotidase activity in the earthworm nerve cord seemed to be restricted to the microsomal fractions (endomembrane network), with a very low activity associated with the large plasma and myelin-like membrane fraction. We have established the presence of keratins or prekeratins in the myelin-like membranes, probably in the form of tonofilaments. However, we could not show that the desmosome-like structures, characteristic of these membranes, are composed of those proteins described for vertebrate epithelial desmosomes.

Studies on subcellular fractions which are involved in myelin membrane assembly: isolation from developing mouse brain and characterization by enzyme markers, electron microscopy, and electrophoresis.

An extensive scheme for the subcellular fractionation of myelinating mouse brain is presented. Several centrifugation procedures for the separation of membranes involved in myelinogenesis are critically appraised, and guidelines for selection of centrifugation conditions are given. Characteristics of subcellular fractions are presented in the form of electron micrographs; also presented are distribution of RNA and protein; electrophoretic profiles of membrane proteins, and verification of the myelin-specific basic proteins, proteolipid protein, and glycoprotein by the immuno-electroblot technique; and the distribution of eight marker enzyme activities. Myelin-related membranes were found to differ both qualitatively and quantitatively in their complement of myelin-specific proteins. These myelin-containing fractions appear to represent different stages of myelination that coexist in developing mouse brain. These results provide the fundamental methodologies and background information for kinetic radioisotope analysis of intracellular events in the assembly of myelin presented in a companion article.

Triton X-100 extractions of central nervous system myelin indicate a possible role for the minor myelin proteins in the stability in lamellae.

Isolated CNS myelin membranes were extracted with Triton X-100 under conditions previously established for the isolation of cytoskeletal proteins. Treated myelin retained much of its characteristic lamellar structure despite the removal of most of the major myelin basic protein (18.5 kDa) and the proteolipid protein, which together normally constitute 60% of the total myelin protein. The SDS-PAGE profile of this extract residue demonstrated an enrichment in proteins of Mr 30 to 60 kilodaltons (the Wolfgram group). The major myelin proteins were identified by antibodies on Western immunoblots, as were the 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNP), actin, tubulin, myelin-associated glycoprotein (MGP) and the 21.5 kDA MBP. The overall behavior of CNP, the 21.5 kDa MBP, MGP and tubulin towards Triton extraction is reminiscent of the behavior of other membrane-skeletal complexes, supporting the idea that these and other minor myelin proteins might be part of heteromolecular complexes with interactions spanning several lamellae of the myelin sheath.

Neuropathology in patients with congenital heart disease and Down syndrome.

This report examines the relationship between congenital heart disease (CHD) and neuropathological findings in three groups of patients: Down syndrome (45 cases), isolated CHD (296 cases), and CHD with multiple anomalies (92 cases). The increase in brain weight in Down syndrome was similar to control standards up to 1 year of age, after which it was less than normal. Among the three groups, there were differences in frequency in cyanotic CHD, history of operation, and macroscopic and microscopic brain malformations. The incidence of calcification in the brain was increased in Down syndrome. Nine children out of the total cohort had cerebrovascular abnormalities. Although CHD is frequent in Down syndrome, the cerebrovasculature is spared; only infrequent minor abnormalities of the circle of Willis were detected.

Delayed maturation of the vagus nerve in sudden infant death syndrome.

Abnormalities of the respiratory control system have been implicated in the cause of death in sudden infant death syndrome (SIDS). The vagus nerve is a major component of the neural regulation of respiration. Ultrastructural quantitative morphometry of myelinated and unmyelinated fibers was performed on cervical vagus nerves taken from 30 SIDS victims and 29 age-matched controls between 1 and 9 months of age. In SIDS infants, more small and fewer large myelinated vagal fibers were found than in controls, suggesting that the vagus nerve in SIDS is relatively immature. Delayed vagal nerve maturation, together with delays in central nervous system myelination and dendritic development, indicates a neural developmental delay in SIDS, the cause of which is undetermined.

Studies on subcellular fractions which are involved in myelin assembly: labeling of myelin proteins by a double radioisotope approach indicates developmental relationships.

The question of developmental relationships amongst myelin-related membranes in subfractions of myelinating mouse brain (15 days) was investigated by a time-staggered double isotope protocol using [3H]leucine and [14C]leucine. Preliminary results are interpreted and discussed in the context of a mathematical conceptualization of pulse-labeling kinetic analyses of myelin proteins in subcellular membrane compartments. Differences in ratio of the two leucine labels among proteins of myelin-containing subfractions are interpreted as confirming metabolic differences relating to various stages of development rather than precursor-product relationships. The incorporation into myelin of 14K, 17K, and 18.5K basic proteins (MBPs) occurs with relatively short delay times, following their synthesis (less than 5 min), and seems to occur simultaneously into all compartments. The 21.5K MBP and the proteolipid protein, on the other hand, require 10-14 min and 14-20 min, respectively. A scheme is presented to illustrate the probable assignment of subfractions to various myelin "compartments" during myelination, and to serve as a working hypothesis for studies on precursor-product relationships.