Purification and characterization of bovine brain type I phosphatidylinositol kinase

Investigation into the phosphatidylinositol kinase activities in bovine brain has revealed the presence of a type I PtdIns kinase activity. This classification is based upon potent inhibition by neutral detergent and the production of a phosphatidylinositol phosphate that can be distinguished from phosphatidyl-inositol-4-phosphate [PtdIns(4)P] by thin-layer chromatography. The enzyme has been substantially purified and the activity is associated with an 85-kDa polypeptide on SDS/polyacrylamide gel electrophoresis. Analysis of the product confirms the identification of the enzyme as a type I PtdIns kinase. The purified kinase has been characterized with respect to substrate dependence (Mg2+, ATP, PtdIns), substrate presentation (pure lipid versus mixed micelle) and specificity [PtdIns versus PtdIns(4)P and phosphatidylinositol 4,5-bisphosphate].     

Earliest mechanical evidence of cross-bridge activity after stimulation of single skeletal muscle fibers.

The stiffness of single fibers from frog skeletal muscle was measured by the application of small 2-kHz sinusoidal length oscillations during twitch and tetanic contractions at a range of initial sarcomere lengths. The earliest mechanical signs of activation were a fall in tension (latency relaxation) and a rise in stiffness. The earliest stiffness increase and the earliest tension fall occurred simultaneously at all sarcomere lengths. This suggests a cross-bridge origin for the latency relaxation. The lead of stiffness over tension seen during the rise of tension was substantially established during the latent period. Reducing the size of the twitch by reducing calcium release with D-600 (methoxyverapamil) reduced the latency relaxation and the stiffness development during latency much less than it reduced the twitch tension. For very small twitches the peak of the stiffness response occurred during the latent period and the times of onset of both latency relaxation and stiffness rise were delayed, but remained coincident. This suggests a strong connection between the latency relaxation and the rise of stiffness during the latent period, whereas the connection between these events and positive tension generation appears to be less strong.     

A simple procedure for isolation and purification of A-type staphylococcus enterotoxin

A new procedure is presented for the isolation and purification of A-type staphylococcus enterotoxin. Homogeneous enterotoxin preparation was obtained by purification in 2 phases. In radial double agar-gel immunodiffusion the smallest precipitating dose of the isolated and purified enterotoxin was found to be 1.4-0.7 micrograms protein and 0.4-0.1 micrograms nitrogen. In cat experiments the dose giving a positive reaction was 2 micrograms protein or 0.5 micrograms nitrogen calculated for kg body weight.     

The accumulation and intracellular compartmentation of cadmium,lead, zinc and calcium in two earthworm species (Dendrobaena rubida and Lumbricus rubellus) living in highly contaminated soil

Summary The earthworm Lumbricus rubellus contained more Ca and Zn, and less Pb and Cd, than Dendrobaena rubida living in the same contaminated disused-mine soil. Differences in the kinetics of Ca turnover may account for some of the inter-specific differences in heavy metal burdens, although the calciferous glands do not seem to be directly involved in heavy metal excretion. A comparison of the present findings with published data indicated that the concentration of soil Ca and the bioavailability of heavy metals, both factors being allied to soil pH, are important exogenous determinants of heavy metal accumulation by different earthworm populations. Electron microprobe X-ray analysis of air-dried smears of chloragogenous tissue showed that the metals were fairly specifically compartmentalized into two distinct organelles in both worms: Ca, Pb and Zn were found (associated with P) in the chloragosomes; Cd was found (with S and probably in stoichiometric association) in a more electron-lucent vesicular component, designated the cadmosome, but which may be identical with the debris vesicles which are characteristic inclusions in conventionally-fixed chloragocytes. The in vivo incorporation of Pb by the chloragosomes of D. rubida was accompanied by the loss of Ca, Zn and P.     

Extrahelical bases in duplex DNA

The two non-complementary synthetic DNAs, poly[d(G-G-A)] and poly[d(T-C)] can form a duplex structure at moderate ionic strengths in which every other T is extrahelical:

Only this structure is consistent with the stoichiometry of formation and with the production of C? photodimers on ultraviolet light irradiation. Further characterization with respect to melting temperature and interaction with nuclease or damage-recognizing proteins is described.     

Stimulated fluid secretion is sodium dependent in the Malpighian tubules of Locusta migratoria

The ionic dependencies of stimulated and unstimulated Locusta tubules have been studied. K⁺, Na⁺, Cl^? are essential to both basal and stimulated secretion. K⁺ is secreted against a concentration gradient in unstimulated tubules. In response to diuretic hormone or cAMP application, there is a dramatic influx of K⁺ into the lumen. A high level of Na⁺ and Cl^? in the bathing medium is required to allow maximal fluid secretion. The tubules show an apparent impermeability to Na⁺; its concentration in the secreted fluid is always much less than in the bathing medium. If Na⁺ is omitted from the medium and excess K⁺ added (80 mM K), then although basal secretion occurs (2.5 nl/min), the tubules fail to respond to stimulation. Clearly Na⁺ has an important indirect role to play in stimulated fluid secretion.     

Description and SEM Observations of Meloidogyne chitwoodi n. sp. (Meloidogynidae), a Root-knot Nematode on Potato in the Pacific Northwest

Meloidogyne chitwoodi n. sp. is described and illustrated from potato (Solanum tuberosum) originally collected from Quincy, Washington, USA. This new species resembles M. hapla, but its perineal pattern is basically round to oval with distinctive and broken, curled, or twisted striae around and above the anal area. The vulva is in a sunken area devoid of striae. Vesicles or vesicle-like structures are present in the median bulb of females. The larva tail, being short and blunt with a hyaline tail terminal having little or no taper to its rounded terminus, is distinctively different from M. hapla. SEM observations revealed the nature of the perineal pattern and details of the head of larvae and males, and showed the spicules to have dentate tips ventrally. Hosts for M. chitwoodi n. sp. include potato, tomato, corn, and wheat but not strawberry, pepper, or peanut. The latter three crops are excellent hosts for M. hapla. The known distribntion of this new root-knot species presently involves certain areas of Idaho, Washington, and Oregon. The common name "Columbia root-knot nematode" is proposed for M. chitwoodi n. sp.