Bark and Leaf Lectins of Sophora japonica Are Sequestered in Protein-Storage Vacuoles

The leguminous tree Sophora japonica contains a family of closely related, but distinct, lectins. Different members of this family are independently expressed in seeds, leaves, and bark (CN Hankins, J Kindinger, LM Shannon 1987 Plant Physiol 83: 825-829; 1988 Plant Physiol 86: 67-10). The inter-, and intracellular distribution of the bark and leaf lectins was studied by indirect postembedding immunogold electron microscopy. Aldehyde fixed bark and leaves postifixed with OsO₄ and embedded in LR White resin permitted sensitive and specific immunogold labeling while maintaining cellular ultrastructure. The leaf and bark tissue cells contain protein-filled storage vacuoles which occupy most the cell's interior volume. The leaf and bark vacuoles closely resemble the protein bodies, or protein storage vacuoles, of seed cotyledons. The leaf and bark lectins were found to be exclusively sequestered in the protein-storage vacuoles of these tissues.     

Rapid determination of DNA synthesis in adherent cells grown in microtiter plates

A specific, rapid, and economical method for measuring the extent of DNA synthesis in adherent rat hepatoma H4-II-E cells grown in 96-well microtiter plates is described. The adherent cells were pulsed for 1 h with [methyl-3H]thymidine, released from the substratum by trypsinization, and collected on fiberglass filters with a MASH II cell harvester. The amount of radioactivity incorporated was directly proportional to the number of cells per well. Growth curves generated by measuring [methyl-3H]thymidine incorporation and counting the number of cells per well were identical. Experiments with inhibitors of DNA, protein, and RNA synthesis demonstrated that this method selectively measured DNA synthesis. In addition, [3H]thymidine uptake showed excellent correlation with autoradiographic assessment of DNA synthesis. This specific and sensitive method for determining DNA synthesis in microtiter cultures should facilitate studies of effects of various growth-controlling agents on epithelial, fibroblastic, and other cells which grow as adherent cells in culture.     

Variation in heat-shock proteins among species of desert fishes (Poeciliidae, Poeciliopsis)

Analysis of the heat-shock proteins (hsps) of six closely related species of Poeciliopsis demonstrated the existence of biochemical diversity in the hsp100, hsp70, hsp60, and hsp30 protein families among species. Each species expressed five to seven hsp70-related isoforms. Constitutive 70-kD isoforms were identical among species, but four different patterns of heat-inducible isoforms were seen in these six species. Members of the hsp70 family of molecular chaperones are included among the most highly conserved proteins known, and the possibility of variation in hsp70 among closely related species has rarely been addressed. The hsp30 family is known to be less conserved than the hsp70 family, and, as expected, the Poeciliopsis hsp30 patterns showed more variation. Most of the hsp30 isoforms characteristic of a particular species were unique to that species. Hsp100 and hsp60 were identical in five of the species, but alternate isoforms were found in P. monacha. The small size and limited geographical distribution of the P. monacha population have probably contributed to the uniqueness of the monacha pattern. Two of the species were shown to acquire thermotolerance, the ability to withstand normally lethal temperatures when subjected to a gradual temperature increase. Rapid-heating protocols commonly used to establish critical thermal maxima of organisms do not include this inducible component of thermoresistance and therefore do not adequately assess an organism's capacity to withstand thermal stress.      

Significance of betaines in the increased chlorophyll content of plants treated with seaweed extract

Seaweed extract, prepared by alkaline extraction of Ascophyllum nodosum (L.) Le Jol., applied either to the soil or to the foliage of tomato plants, produced leaves with higher chlorophyll levels than those of control plants. The effects on leaf chlorophyll content were investigated using a cucumber bioassay procedure devised for cytokinins. The seaweed extract was shown to increase the chlorophyll levels of the cucumber cotyledons, but ‘peaks’ of activity were obtained when widely different concentrations were used. The possibility that these effects were the result of betaines present in the extract was considered. Glycinebetaine, γ-aminobutyric acid betaine and δ-aminovaleric acid betaine all produced significantly enhanced chlorophyll concentrations in the cotyledons. ‘Peaks’ of activity were observed for each betaine: for glycinebetaine at 10⁻⁶ and between 10⁻⁴ and 10¹ mg 1⁻¹, for γ-aminobutyric acid betaine at 10⁻⁶, between 10⁻⁴ and 10⁻¹, and 10¹ mg 1⁻¹, and for δ-aminovaleric acid betaine between 10⁻⁵ and 10¹ mg 1⁻¹. It was concluded that the effects of enhancing chlorophyll levels produced by the seaweed extract were due, at least in part, to betaines.     

Retention deficit for avoidance training in hypophysectomized rats: Time-dependent enhancement of retention performance with post-training ACTH injections

These experiments examined the effects of hypophysectomy on retention of avoidance training. In addition, the experiments examined the effects, on retention, of post-training ACTH injections administered to hypophysectomized rats. Rats were trained in a visual discriminated avoidance Y maze. Each rat received six training trials followed by six retraining trials the next day. Retention was measured by the number of correct choices during the retraining trials. When trained with a low-footshock intensity (0.8 mA), hypophysectomized rats showed retention performance which was significantly poorer than that of intact animals. There was no significant difference in performance when the animals were trained with a higher footshock intensity (1.4 mA), in part because of poorer retention performance of intact animals under these training conditions. Under both footshock conditions, a single post-training injection of ACTH enhanced later retention performance of hypophysectomized rats. This effect on memory was timedependent; injections delayed 2 or 6 hr after training did not significantly enhance retention. These findings are consistent with the view that hormonal responses to training may modulate later retention of the training experience.     

The myeloproliferative sarcoma virus causes transformation or erythroid progenitor cells in vitro

The myeloproliferative sarcoma virus induces spleen focus formation in vivo and transforms fibroblasts in vitro. We showed in this study that in vitro infection of spleen or bone marrow cells from susceptible mice with the myeloproliferative sarcoma virus leads to the formation of erythroid bursts. Under optimal conditions erythroid bursts formed in the absence of added erythropoietin, but the addition of as little as 0.05 U of erythropoietin per ml to infected cultures resulted in a significant increase in numbers of erythroid bursts and the proportion of hemoglobinized cells. A comparison of the kinetics of burst formation and the size of the induced bursts with those induced with Friend virus suggested that either sarcoma virus such as the myeloproliferative sarcoma virus or the target cells for the two viruses were not the same. Density characterization and heat lability studies indicated that the increased erythroid proliferation in vitro was a virus-induced event, but the possibility that the induced erythroid burst formation is mediated via interaction with a nonerythroid target cell and subsequent release of a soluble factor cannot be ruled out.     

Molecular properties of the enzymic phytohemagglutinin of mung bean

Mung bean seeds possess a tetrameric galactose-binding protein that displays two types of activities: (a) a hemagglutinin activity, and (b) an alpha-galactosidase activity. This protein can be reversibly converted by pH changes from a tetrameric form, which possesses both enzymic and hemagglutinin activities, to a monomeric form which possesses enzymic activity only. This observation suggests that the enzymic phytohemagglutinin is an aggregated form of a monomeric alpha-galactosidase. The tetrameric alpha-galactosidase has a pH optimum of about pH 7.0, while the monomeric form displays a pH optimum of 5.6. Circular dichroism difference spectra and inhibition studies suggest that aggregation induces conformational changes in the subunits sufficient to alter their enzymatic properties. The possibility of in vivo changes in subunit equilibria, when combined with the accompanying alterations in activity, provides a new concept worthy of consideration with respect to the physiological role of phytohemagglutinins.     

Hydroxyurea Use and Hospitalization Trends in a Comprehensive Pediatric Sickle Cell Program

Background

A decline in hospitalizations and pain episodes among those with sickle cell disease (SCD) who take hydroxyurea (HU) has been shown when compared to pre-HU patterns but paradoxically, when compared to those who have never been treated, HU recipients often have more frequent hospitalizations. This analysis evaluates the impact of increasing usage of HU on trends in hospitalizations and blood transfusions within a large SCD treatment program.

Methods

Eligibility was restricted to patients with Hb SS or Hb Sβ⁰-thalassemia who were 2–18 years old between 2006–2010 and received care at St. Jude Children''s Research Hospital (N = 508). Hospitalizations and blood transfusions were calculated for each of the years under study for those exposed and never exposed to HU. Differences in number of hospitalizations before and after HU initiation were compared.

Results

The proportion of patients receiving HU increased by 4% per year on average. In the HU exposed group, a modest decline in mean per-patient hospitalizations and per-patient hospital days occurred, while those never exposed to HU trended toward a slight increase over time. Rates of blood transfusions declined among those on HU but not in patients never exposed to HU. Patients on HU had a median of one fewer hospital admission in the year after initiation of HU, compared to the year prior. Two deaths occurred in the patient population, both of whom were not exposed to HU.

Conclusions

Increasing usage of HU was concurrent with decreased hospitalization rates and blood transfusions. Our results support the utility of HU on decreasing hospitalizations and transfusions for patients with SCD outside of the clinical trial setting.