Structural changes occurring in interrenal tissue of the duck (Anas platyrhynchos) following adenohypophysectomy and treatment in vivo and in vitro with corticotropin

Adrenal glands from ACTH-treated intact ducks and chronically adenohypophysectomized ducks showed clear zonation into a subcapsular zone (SCZ) and an inner zone (IZ). Adenohypophysectomy caused ultrastructural changes in the IZ but not in the SCZ cells. These included increases in lipid droplets, changes in mitochondrial cristae from tubular to shelf-like, and changes in the shape of the nuclei from spherical to crenated. These changes were reversed by treatment with ACTH. Also, cells of the IZ, but not the SCZ, of adrenals from intact birds given ACTH showed more SER, more dense bodies, fewer lipid droplets and more prominent Golgi complexes. IZ cells incubated in buffer containing no ACTH developed mitochondria with shelf-like cristae and numerous opaque granules in the matrix. Exposure to buffer containing ACTH caused the mitochondrial cristae to become tubular and the matrix granules either decreased in number or disappeared. The granules could be extracted by incubating sections with chelating agents. The mitochondria in SCZ cells did not respond structurally to the presence of ACTH in the incubation medium but the matrix granules, like those in IZ cells, responded to the presence of chelating agents.     

Multiple toxin production by an isolate of Aspergillus flavus

Three toxins were recovered from rice and wheat cultures of an isolate of Aspergillus flavus. The toxins were present simultaneously in the cultures after one or two weeks incubation and were identified as aflatoxin, cyclopiazonic acid and aflatrem, a recently identified indole-mevalonate metabolite.No endorsements are implied herein.     

Calcium and magnesium in Mueller-Hinton agar and their influence on disk diffusion susceptibility results

Concentrations of calcium and magnesium were determined for 39 lots of media, including broth and agar media used for susceptibility tests and plain agar. In addition, the effect that media with and without physiological levels of these divalent cations would have on the disk diffusion susceptibility of 21 strains ofPseudomonas aeruginosa to four antimicrobics was also ascertained. Mueller-Hinton agar showed a wide variation in calcium and magnesium content. Mueller-Hinton broth contained lower concentrations of calcium and magnesium, and there was little lot-to-lot variation. Lots of Mueller-Hinton agar with higher concentrations of calcium and magnesium yielded smaller zone diamaters than those with lower concentrations. Even at equal cation concentration, zones of inhibition varied from lot to lot. Since the addition of calcium and magnesium to Mueller-Hinton agar to obtain a predetermined level did not result in equivalent zone diameters, performance testing of susceptibility media is recommended.     

Effect of temperature on isotonic twitch of white muscle and predicted maximum swimming speeds of skipjack tuna,Katsuwonus pelamis

Synopsis Latent period, rise time, contraction time, and half relaxation time from isotonic contractions of isolated white muscle samples from skipjack tuna, Katsuwonus pelamis, were determined at 20°, 27°, and 34° C. These parameters were found to be inversely proportional to temperature (Q₁₀ = 1.47, 1.67, 1.62, and 1.72, respectively). The data show that contraction time and the effect of temperature on contraction time of skipjack tuna white muscle are not unique when compared to other equal-sized teleosts. Based on contraction time, maximum swimming speeds at each muscle temperature were calculated and found not significantly to exceed the maximum speeds of other equal-sized teleosts, when comparisons are made at the same white muscle temperatures     

Reconstituted low density lipoprotein: A vehicle for the delivery of hydrophobic fluorescent probes to cells

Previous studies have shown that the cholesteryl ester core of plasma low density lipoprotein (LDL) can be extracted with heptane and replaced with a variety of hydrophobic molecules. In the present report we use this reconstitution technique to incorporate two fluorescent probes, 3-pyrenemethyl-23, 24-dinor-5-cholen-22-oate-3β-yl oleate (PMCA oleate) and dioleyl fluorescein, into heptane-extracted LDL. Both fluorescent lipoprotein preparations were shown to be useful probes for visualizing the receptor-mediated endocytosis of LDL in cultured human fibroblasts. When normal fibroblasts were incubated at 37°C with either of the fluorescent LDL preparations, fluorescent granules accumulated in the perinuclear region of the cell. In contrast, fibroblasts from patients with the homozygous form of familial hypercholesterolemia (FH) that lack functional LDL receptors did not accumulate visible fluorescent granules when incubated with the fluorescent reconstituted LDL. A fluorescence-activated cell sorter was used to quantify the fluorescence intensity of individual cells that had been incubated with LDL reconstituted with dioleyl fluorescein. With this technique a population of normal fibroblasts could be distinguished from a population of FH fibroblasts. The current studies demonstrate the feasibility of using fluorescent reconstituted LDL in conjunction with the cell sorter to isolate mutant cells lacking functional LDL receptors.     

Time and process of sperm penetration into cumulus-free mouse eggs fertilized in vitro

Sperm penetration through the zona pellucida and fusion of the sperm head with the vitellus were observed continuously and filmed under phase optics in cumulus-free living mouse eggs inseminated in vitro with capacitated epididymal sperm. Most spermatozoa penetrated the zona pellucida, traversed the perivitelline space, and fused with the vitellus at an angle nearly perpendicular to the surface. The mean duration required for sperm to penetrate the zona pellucida was 20 minutes with a range of 15–26 minutes. Sperm traversed the perivitelline space in less than one second. The initial contact of sperm with the vitellus generally took place at the tip of the sperm head. When the tip of the sperm head contacted the vitellus there was an immediate reduction in the rate of flagellation, followed by the gradual sinking of the sperm head into the vitellus.     

Prostaglandin F concentrations in utero-ovarian vein plasma of prepuberal and mature gilts

Prostaglandin F (PGF) and progestins in utero-ovarian vein (UOV) plasma during the late luteal phase of the estrous cycle in unbred mature gilts and following induced ovulation in unbred prepuberal gilts were determined. Prepuberal gilts (120 to 130 days of age) were induced to ovulate with Pregnant Mare Serum Gonadotropin and Human Chorionic Gonadotropin (HCG). The day following HCG was designated as Day 0. Mature gilts which had displayed two or more estrous cycles of 18 to 22 days (onset of estrus = Day 0) were used. Polyvinyl catheters were inserted into the UOV of all gilts and blood was collected at 15 min intervals from 0800 to 1045 hr on Days 10 through 20 or Days 12 through 18. Plasma PGF concentrations in the mature gilts were elevated on Days 13, 14, 15, 16 and 17, whereas, plasma PGF concentrations in the prepuberal gilts were elevated only on Days 15, 16 and 17 resulting in a reproductive age (mature vs prepuberal) by day interaction (P<.01). In addition, the PGF concentrations on Days 13 through 17 were consistently greater in the mature gilts than in the prepuberal gilts as was the overall mean PGF concentration (1.95 vs .83 ng/ml). The average peak PGF concentration throughout the sampling period (4.6 vs 2.5 ng/ml; P<.01) and the average peak PGF concentration prior to luteal regression (3.8 vs 1.1 ng/ml; P<.05) were also greater in the mature than in the prepuberal gilts. Based on these results, we suggest that luteal regression in the bred prepuberal gilt following induced ovulation may not be due to an excessive production of the uterine luteolysin, but rather that the induced corpora lutea (CL) of the prepuberal gilt may be more sensitive to the uterine luteolysin than the spontaneously formed CL of the mature gilt.