Blastomycosis in wild wolves

Blastomycosis was fatal to a wild wolf in Minnesota, and serologic evidence of blastomycosis was found in a Wisconsin wolf. No unusual movements were detected in the Minnesota animal from October 1983 through October 1985. However, by early December 1985, this wolf was weak and debilitated, and it perished on 14 December after approaching a human residence.     

A homeobox-containing marker of posterior neural differentiation shows the importance of predetermination in neural induction

A homeobox sequence has been used to isolate a new Xenopus cDNA, named XIHbox6. A short probe from this gene serves as an early marker of posterior neural differentiation in the Xenopus nervous system. The gene recognized by this cDNA sequence is first transcribed at the late gastrula stage and solely in the posterior neural cells. The gene is expressed when ectodermal and mesodermal tissues of an early gastrula are placed in contact, but not by either tissue cultured on its own. However, gene expression is most easily inducible in ectoderm from the dorsal region, i.e., in ectoderm normally destined to form neural structures. This establishes the principle, in contrast to previous belief, that the induction of the embryonic nervous system involves a predisposition of the ectoderm and does not depend entirely on an interaction with inducing mesoderm.     

5-aza-C-induced changes in the time of replication of the X chromosomes of Microtus agrestis are followed by non-random reversion to a late pattern of replication

Treatment with 5-azacytidine (5-aza-C) causes an advance in the time of replication and enhances the DNase-I sensitivity of the inactive X chromosome in Gerbillus gerbillus fibroblasts. We found that these changes were not stably inherited and upon removal of the drug the cells reverted to the original state of one active and one inactive X chromosome. In order to determine whether this reversion was random, we used a cell line of female Microtus agrestis fibroblasts in which the two X chromosomes are morphologically distinguishable. In this work we show that the reversion to a late pattern of replication is not random, and the originally late replicating X chromosome is preferentially reinactivated, suggesting an imprinting-like marking of one or both X chromosomes. The changes in the replication pattern of the X chromosome were associated with changes in total DNA methylation. Double treatment of cells with 5-aza-C did not alter this pattern of euchromatin activation and reinactivation. A dramatic advance in the time of replication of the entire X linked constitutive heterochromatin (XCH) region was however, observed in the doubly treated cells. This change in the replication timing of the XCH occurred in both X chromosomes and was independent of the changes observed in the euchromatic region. These observations suggest the existence of at least two independent regulatory sites which control the timing of replication of two large chromosomal regions.Deceased on 2 Jan. 1987     

Comparison of bacterial counts obtained from naturally contaminated foods by means of Stomacher and blender

Four Regional Health Protection Branch laboratories each compared aerobic colony counts obtained after "stomaching" and blending, for a minimum of 10 samples in each of the seven food groups: dry pastas; chocolate and cocoa powders; frozen entrees (macaroni and cheese, chow mein, chop suey, fried rice, seafood casseroles, and Salisbury steak); nonfat dry milk; shrimp and crabmeats; spices; and breakfast sausages. Overall, counts obtained after using the Stomacher were equivalent to or higher than counts obtained after using the blender in 73% of the comparisons (alpha = 0.05). Where differences existed, counts obtained after using the Stomacher tended to be higher than counts obtained after using the blender from milk powder and lower from sausage. Aerobic colony counts from these foods are not unacceptably biased when obtained by Stomacher.     

Origin of regenerating Leydig cells in the testis of the adult rat

Summary Ethane dimethanesulphonate (EDS) was used as a specific cytotoxin to eliminate the Leydig cell population of the adult rat testis. Ultrastructural, morphometric and serum gonadotrophin and testosterone analysis was used to study the response of the intertubular tissue of the testis from 1 day to 10 weeks after EDS treatment. In control animals, the testis contained approximately 28 million Leydig cells and 8 million macrophages. Three to seven days after EDS treatment, Leydig cells were absent and serum testosterone was undetectable. Macrophage numbers increased three-fold by 3 days and returned to pretreatment values thereafter. At 2 and 3 weeks post-EDS, foetal-type Leydig cells (1–2 million per testis) appeared in proximity to perivascular and peritubular tissues, a feature also observed at 4 weeks when numerous such cells (15 million per testis) formed prominent clusters in perivascular and peritubular locations. Between 6 and 10 weeks after EDS treatment, the foetal-type Leydig cells were transformed morphologically into adult-type Leydig cells, they occupied central intertubular positions and their numbers were restored to pretreatment values. Regeneration of Leydig cells was reflected by elevated serum testosterone levels which returned towards the normal range. The results demonstrate the regenerative capacity of the testicular intertubular tissue and indicate a dual site of origin of Leydig cells which initially resemble foetal-type Leydig cells prior to establishing the adult-type Leydig cell population. The morphological pattern of Leydig cell regeneration suggests that in addition to gonadotrophic stimulation, local testicular factors from the seminiferous tubules may stimulate Leydig cell growth.     

Cerebral glycine content and phosphoserine phosphatase activity in hyperaminoacidemias

Chronic hyperphenylalaninemia maintained with the aid of a suppressor of phenylalamine hydroxylase, -methylphenylalanine, increases the glycine concentration and the phosphoserine phosphatase activity of the developing rat brain but not that of liver or kidney. Similar increases occur after daily injections with large doses of phenylalanine alone, while tyrosine, isoleucine, alanine, proline, and threonine, were without effect. Treatment with methionine, which increases the phosphoserine phosphatase activity of the brain and lowered that of liver and kidney, left the cerebral glycine level unchanged. When varying the degrees of gestational or early postnatal hyperphenylalaninemia, a significant linear correlation was found between the developing brains' phosphoserine phosphatase and glycine concentration. Observations on the uptake of injected glycine and its decline further indicate that coordinated rises in the brain's phosphoserine phosphatase and glycine content associated with experimental hyperphenylalaninemia denote a direct impact of phenylalanine on the intracellular pathway of glycine synthesis in immature animals.     

Morphometric analysis of collagen in gestational and retained bovine placentomes

Bovine placentome collagen was quantified (P<0.01) at four gestational stages (90, 150, 210 and 270 d, n = 8 d ), at 2 h post partum without (n = 4) and at 2 and 12 h post partum with (n = 8) experimentally-induced placental retention. Placentome sections were fixed and stained for collagen. Fetal cotyledonary (FC) collagen volume fraction (V(V)) increased over days of gestation studied (V(V)=0.03+/-0.01, 0.06+/-0.01, 0.13+/-0.01 and 0.19+/-0.01). Fetal cotyledonary hydroxyproline (3.15+/-0.41, 4.55+/-0.41 and 7.04+/-0.41 mg/g) and FC protein (432.0+/-17.1, 479.9+/-17.1, 585.4+/-17.1 mg/g) increased over Days 90, 150 and 210 and were similar on Days 210 and 270. Fetal cotyledonary collagen V(V) and hydroxyproline did not differ between Day 270, retained and nonretained cotyledons. Protein concentration was higher in 2 h (578.1+/-18.5 mg/g) and 12 h (526.0+/-18.5 mg/g) retained versus nonretained (400.4+/-36.2 mg/g) cotyledons. Maternal caruncular (MC) collagen V(V) and protein concentration were higher on Days 90 and 150 than on Days 210 and 270. Maternal caruncular hydroxyproline was similar from Day 90 to 210 and increased from Day 210 to 270. Maternal caruncular collagen V(V), hydroxyproline and protein concentrations were similar on Day 270 and in 2 h and 12 h retained membrane caruncles. Gestational increases in placentome collagen occurred from FC sources. No difference in FC or MC collagen V(V) existed between Day 270, retained and nonretained placentomes.     

Ultrastructure of carotenoid deprivation in photoreceptors of Manduca sexta: myeloid bodies and intracellular microvilli

Summary The ultrastructural effects of carotenoid (vitamin A) deprivation were studied in the adult photoreceptors of the tobacco hornworm moth Manduca sexta. Moths were reared on a deprived diet, which lacked the carotenoid sources of the photopigment chromophore, 3-hydroxy retinal, or on a control, fortified diet, containing ample carotenoid. The latter supported normal levels of visual function, whereas visual pigment and sensitivity were reduced by at least 3 log units in moths reared on the deprived diet. Myeloid bodies, massed cisternae of hypertrophied smooth endomembrane, filled the cytoplasm in the receptors of deprived animals. The myeloid bodies assumed various configurations that included lamellate stacks of parallel cisternae, and tubular networks in a paracrystalline form. Freeze-fracture preparations of myeloid membranes revealed a high density of P-face particles. Vacuoles containing microvilli similar to those of the rhabdomere were also present in deprived photoreceptors. We suggest that the elaboration of smooth endoplasmic reticulum as myeloid bodies in chromophore-deprived photoreceptors may stem from the hypertrophy of a biochemical system for processing the chromophore or the interruption of the intracellular pathway that normally carries visual pigment to the rhabdomere.