Photocontrol of subcellular partitioning of phytochrome-B:GFP fusion protein in tobacco seedlings.

Photomorphogenesis of higher plants is regulated by photoreceptors including the red/far-red light-absorbing phytochromes, blue-UV/A sensing cryptochromes and as yet uncharacterized UV/B receptors. Specific phototransduction pathways that are controlled by either individual or interacting photoreceptors mediate regulation. Phytochrome B (phyB) is the major red light-sensing photoreceptor. Phototransduction mediated by this light sensor has been shown to include light-dependent nuclear import and interaction of phyB with transcription factor-like proteins in the nucleus. Here we report that nuclear import of phyB and physiological responses regulated by this photoreceptor exhibit very similar wavelength- and fluence rate-dependence. Nuclear import of phyB is insensitive to single red, blue and far-red light pulses. It is induced by continuous red light and to a lesser extent by continuous blue light, whereas far-red light is completely ineffective. The data presented indicate that light-dependent partitioning of phyB exhibits features characteristic of blue light responsiveness amplification, a phenomenon that is thought to be mediated by interaction of phyB with CRY1.

Comparison of the fuel oil biodegradation potential of hydrocarbon-assimilating microorganisms isolated from a temperate agricultural soil.

Strains of hydrocarbon-degrading microorganisms (bacteria and fungi) were isolated from an agricultural soil in France. In a field, a portion was treated with oily cuttings resulting from the drilling of an onshore well. The cuttings which were spread at the rate of 600 g HC m-2 contained 10% of fuel oil hydrocarbons (HC). Another part of the field was left untreated. Three months after HC spreading, HC adapted bacteria and fungi were isolated at different soil depths in the two plots and identified. The biodegradation potential of the isolated strains was monitored by measuring the degradation rate of total HC, saturated hydrocarbons, aromatic hydrocarbons and resins of the fuel. Bacteria of the genera Pseudomonas, Brevundimonas Sphingomonas, Acinetobacter, Rhodococcus, Arthrobacter, Corynebacterium and fungi belonging to Aspergillus, Penicillium, Beauveria, Acremonium, Cladosporium, Fusarium, and Trichoderma were identified. The most active strains in the assimilation of saturates and aromatics were Arthrobacter sp., Sphingomonas spiritivorum, Acinetobacter baumanii, Beauveria alba and Penicillum simplicissimum. The biodegradation potential of the hydrocarbon utilizing microorganisms isolated from polluted or unpolluted soils were similar. In laboratory pure cultures, saturated HC were more degraded than aromatic HC, whereas resins were resistant to microbial attack. On an average, individual bacterial strains were more active than fungi in HC biodegradation.

Effect of freezing and thawing on cell membranes of Lentinus edodes, the shiitake mushroom.

When cell membranes of Lentinus edodes mycelium were rapidly frozen at either 50 or 160°C/min, viability was lost and this correlated with rupture of the plasmalemma and residual membrane material and with alterations in the organelles. Although with slow cooling (1°C/min) 80% of the samples recovered viability, some cells still showed similar changes to those cooled rapidly, indicating that individual cells of the mycelium do not respond in the same way.

Magnetic resonance imaging of lipomyelomeningocele and tethered cord.

The operative and magnetic resonance image (MRI) findings of 25 patients with the diagnosis of lipomyelomeningocele and/or tethered cord were compared. Postoperative MRI scans of eight patients, five of whom were in stable condition, were also compared with the preoperative studies. In this review there was one false negative MRI scan and four MRI scans in which the relationship of the lipoma to the conus or filum was not demonstrated accurately. In six patients, incidental intramedullary cystic lesions at the conus were identified by MRI scan. All eight postoperative (1 month to 2 years) scans demonstrated no change in the level of the conus from the preoperative study. MRI is an accurate screening modality in the initial diagnosis of occult spinal dysraphism. MRI was not useful in the postoperative evaluation of lipomyelomeningocele and the tethered cord, since the caudal, posterior displacement of the conus was unchanged in all studies.

Gadolinium-DTPA-enhanced magnetic resonance imaging in childhood brain tumors.

Gadolinium DTPA (Gd-DTPA) is a paramagnetic blood-brain barrier contrast agent for MRI that has been used primarily in adults. During May through October 1987, 17 children between the ages of 3 and 18 years with brain tumors underwent MRI examinations, before and after Gd-DTPA (11 gliomas, 4 medulloblastomas, 1 craniopharyngioma, and 1 child with neurofibromatosis and no pathologic diagnosis). We compared T1 and T2 Gd-DTPA-enhanced MRI with concurrent unenhanced MRI and enhanced CT, and then correlated this with the clinical and pathologic findings. Gd-DTPA enhanced tumors in all 7 patients with newly diagnosed tumors and enhanced tumors in 7 of 10 patients without clinical evidence of progressive disease at the time of the study. In the 7 new patients, Gd-DTPA defined tumor margins in all, and demonstrated internal tumor architecture (vessels, necrosis, and cysts) in 5. Areas believed to represent surgical scars showed varying degrees of enhancement. Leptomeningeal tumor spread, including spinal, not seen on pre-Gd-DTPA MRI or on contrast CT, was evident in 2 patients. Gd-DTPA enhancement obscured hemorrhage within the tumor (methemoglobin) in 2 patients. There were no significant side effects. These results suggest that Gd-DTPA-enhanced MRI (1) is safe in children, (2) demonstrates the extent and character of tumors better than unenhanced MRI and enhanced CT, and (3) may allow for noninvasive imaging of leptomeningeal disease, including the spine, not previously demonstrated by any other noninvasive neuroimaging technique.

The superior mesenteric artery fat plane: is obliteration pathognomonic of pancreatic carcinoma?

Obliteration of the fat plane surrounding the superior mesenteric artery has been described as characteristic of pancreatic carcinoma. To determine the specificity of this and other computed tomography findings in the pancreas and peripancreatic region, scans of 86 patients were reviewed without clinical history. Diagnoses included pancreatitis (26 patients); pancreatic adenocarcinoma (14 patients); lymphoma (17 patients); metastatic nonpancreatic carcinoma (14 patients); and normal findings (15 patients). Confluent adenopathy could not be reliably differentiated from a pancreatic mass except when adenopathy separated the common bile duct from the duodenum. Retrocrural adenopathy was unusual with pancreatic carcinoma. The fat plane surrounding the superior mesenteric artery was obliterated with pancreatic carcinoma (36%), nonpancreatic carcinoma (29%), and lymphoma (24%), but not with pancreatitis, although perivascular edema was seen in 19%. Evaluation of the celiac axis was less rewarding. Obliteration of the superior mesenteric artery fat plane is a sign of malignancy, but it is not specific for pancreatic carcinoma. We propose that the superior mesenteric artery origin be considered within a paraaortic space, separate from the anterior pararenal space. This explains its characteristic lack of involvement by pancreatitis.