Conformation and activity ofPhaseolus coccineus var. rubronanus lectin

The conformation of native and denaturedPhaseolus coccineus var. rubronanus lectin was studied by circular dichroism (CD) and correlated to the hemagglutinating activity. The far-UV CD spectrum at 25°C showed a broad, negative band around 223 nm and a positive one at 196 nm. CD data analysis of the lectin indicated a -sheet-rich protein. At high temperatures, the spectrum was blue-shifted with increasing magnitude; these changes correlated well with the loss of the activity. The conformation of lectin betweenpH 2 and 10 remained essentially unchanged. AtpH 13 the CD spectrum resembled that of unordered form with a negative band near 200 nm and the activity was completely lost. The denatured lectin in 6 M guanidine hydrochloride would be renatured upon diluting the denaturant to 0.75 M; the changes in CD spectrum again correlated well with the loss of the activity. The effect of sodium dodecyl sulfate on the lectin was drastic; it sharply increased thea-helix at the expense of the -sheet and reduced the activity; the changes reached a plateau above 20 mM surfactant.     

The distribution of colony-forming cells in the kidney

Abstract. A method is described for producing outgrowths of small nephron segments (average 24 cells) in culture. The method was used to estimate an overall colony-forming efficiency of 4.6% for cells constituting the segments. Efficiency was found to be lower for thick segments (1%) than for thin segments (6%) from Henle's loop. The latter higher level indicates that precursor cells are concentrated near the middle of the nephron. For comparison, a two-dose irradiation technique was used to calculate a mean number of 5 ± 2 (SE) clonogens per segment producing outgrowths. This tended to be higher than the value of about 1 calculated from the 65% of segments producing outgrowths, as expected if the remaining segments contained no clonogens.     

Thelocarpon cyaneum sp. nov.

Thelocarpon cyaneum, a new lichenicolous fungus on Polyblastia, is described from Antarctica.     

Characterization of phospholipase A2 activation by plasmin in cultured bovine endothelial cells

Treatment of cultured bovine carotid artery endothelial cells with 0.1 µM human plasmin has been reported to induce a receptor-mediated short burst of arachidonate release, which is a pertussis toxin-sensitive and extracellular calcium-dependent reaction. Plasmin-induced calcium influx in cells was significantly inhibited by pretreatment with pertussis toxin, indicating that the former was coupled with a pertussis toxin-sensitive guanosine 5-triphosphate (GTP)-binding protein. Plasmin significantly induced the formation of lysophosphatidylcholine but not lysophosphatidylethanolamine. A cellular phospholipase A₂ with an arachidonyl specificity at the sn-2 position of phosphatidylcholine, which required submicromolar calcium, was identified as a cytosolic phospholipase A₂ by immunoblot analysis. By a cell-free enzyme activity assay and immunoblot analysis, plasmin was found to induce a translocation of the cytosolic phospholipase A₂ from the cytosol to the membrane. Taken together, the results suggest that plasmin bound to its putative receptor and activated a GTP-binding protein coupled to calcium influx channel, followed by translocation and activation of cytosolic phospholipase A₂ in endothelial cells.     

Effects of chronic exercise and deconditioning on platelet function in women

Wang, Jong-Shyan, Chauying J. Jen, and Hsiun-Ing Chen.Effects of chronic exercise and deconditioning on plateletfunction in women. J. Appl. Physiol.83(6): 2080-2085, 1997.To investigate the effects of chronicexercise and deconditioning on platelet function in women, 16 healthysedentary women were divided into control and exercise groups. Theexercise group cycled on an ergometer at 50% maximal oxygenconsumption for 30 min/day, 5 days/wk, for two consecutive menstrualcycles and then were deconditioned for three menstrual cycles. Duringthis period, platelet adhesiveness on a fibrinogen-coated surface,ADP-induced platelet aggregation and intracellular calciumconcentration elevation, guanosine 3,5-cyclic monophosphate (cGMP) content in platelets, and plasma nitric oxide metabolite levels were measured before and immediately after a progressive exercise test in the midfollicular phase. Ourresults indicated that, after exercise training,1) resting heart rates and bloodpressures were reduced, and exercise performance was improved;2) resting platelet function wasdecreased, whereas plasma nitrite and nitrate levels and platelet cGMPcontents were enhanced; and 3) thepotentiation of platelet function by acute strenuous exercise wasdecreased, whereas the increases in plasma nitrite and nitrate levelsand platelet cGMP contents were enhanced by acuteexercise. Furthermore, deconditioning reversed these training effects. This implies that training-induced platelet functional changes in women in the midfollicular phase may be mediatedby nitric oxide.

     

Preference of a revolving target to a stationary one by the big brown bat, Eptesicus fuscus

Utilizing a three-ramp platform, we studied the detection of a revolving and a stationary target in the presence of background clutter by trained Eptesicus fuscus. During the test, the mean amplitude of echo from either target was always larger than that of the background echoes at the bat-to-target distance of 30, 70 and 100 cm. The amplitude of the echo reflected back from a revolving target was modulated between a maximum and a minimum value. An electric motor was used to revolve a target. The frequency contents of the motor noise were mostly below 1 kHz. While the total percent response of approaching either target is always more than 90% at every bat-to-target distance tested, the bats approach a revolving target more frequently than a stationary one. Echolocation pulses emitted by the bats during the test were recorded and analyzed. The bats shortened their pulse durations and interpulse intervals and lowered the frequency contents as they entered into the crawling phase from the searching phase. Potential interference of background echoes and ambient noise with the performance of the bats is discussed. The preference of a revolving target to a stationary one by the bats is perhaps due to the fact that a revolving target has a higher releasing value than a stationary one does.     

A newborn child with karyotype 47,XX,+der(12) (12pter→12q12::8q24→8qter),t(8;12) (q24;q12) pat

Summary A case of Meckel or Gruber syndrome is reported, together with a survey of the relevant literature of recent years (1971–1977), in reference to a probably autosomal recessive inheritance of this malformation.