NITRATE UPTAKE BY LAMINARIA LONGICRURIS (PHAEOPHYCEAE)1,2

Laminaria longicrucis De la Pylaie took up exogenous nitrate under both summer and winter conditions. During July and August no NO₃^- was detected in the ambient water or in algal tissues although it was present in both in February. Discs (2.3 cm diam.) of thin blade tissue were incubated with NO₃^- at four temperatures, with and without illumination. Similar values Jor NO₃^- uptake were found for both summer and winter collected plants when measured in light at 0 C. An apparent K of 4–6 μM was recorded for both types of plants; the V_max ranged from 7 to 10 μmol h^-1 g^-1 dry wt measured in ca. 1800 μW cm^-2 of cool-white fluorescent light. Uptake rates at 5 C were 66%, and at 0 C 30% of those for controls run at 15 C. The alga scavenged NO₃- from solutions <0.5 μM. Ammonia did not inhibit NO₃- uptake. Antibiotic pretreatment reduced NO₃- uptake by a maximum of 12%. Nitrite uptake was inhibited in proportion to the concentration of NO₃- in the medium.     

A study of prostaglandin F2α as the luteolysin in swine: III effects of estradiol valerate on prostaglandin F, progestins, estrone and estradiol concentrations in the utero-ovarian vein of nonpregnant gilts

Polyvinyl catheters were placed into the right and left utero-ovarian veins and saphenous vein and artery of three control (C) and four estradiol valerate (EV) treated gilts on Day 9 after onset of estrus. The EV treated gilts received 5mg EV/day on Days 11 through 15 after onset of estrus. On Days 12 through 17 utero-ovarian vein blood samples were collected at 15 min intervals from 0700 to 1000 hr and 1900 to 2200 hr and single samples were taken at 1100 and 2300 hr. Peripheral blood samples (saphenous vein or artery) were taken at 0700, 1100, 1900 and 2300 hr from Day 12 until the control gilts returned to estrus or until Day 25 for EV treated gilts and used to measure plasma steroid hormone concentrations. Utero-ovarian vein prostaglandin F (PGF) concentrations (ng/ml, n=1,177) were measured by RIA. Status (control EV treated gilts) by day interactions were detected (P=.10). Curvilinear day trends were detected for plasma PGF concentrations in control (P<.01) but not EV treated gilts. PGF concentrations ( ) for control and EV treated gilts were 1.20 ± 2.08 and .26 ± .84 ng/ml, respectively. PGF peaks (concentrations greater than + 2 S.D.) occured with greater frequency in control gilts (X² = 4.87; P<.05). The interestrus interval ( ) for control and treated gilts was 19.0 ± .6 and 146.5 ± 74.8 days, respectively. Data indicate that estradiol valerate may exert its luteotrophic effect by preventing PGF release from the uterus.     

CHLOROPLAST DNA RESTRICTION SITE VARIATION AND THE PHYLOGENY OF COREOPSIS SECTION COREOPSIS (ASTERACEAE)

Restriction site variation in chloroplast DNAs (cpDNAs) of Coreopsis section Coreopsis was employed to assess divergence and phylogenetic relationships among the nine species of the section. A total of fourteen restriction site mutations and one length mutation was detected. Cladistic analysis of the cpDNA data produced a phylogeny that is different in several respects from previous hypotheses. CpDNA mutations divide the section into two groups, with the two perennial species C. auriculata and C. pubescens lacking any derived restriction site changes. The other seven species are united by five synapomorphic restriction site mutations and the one length mutation. These seven species fall into three unresolved clades consisting of 1) the remaining three perennial species, C. grandiflora, C. intermedia, and C. lanceolata; 2) three annual species, C. basalis, C. nuecensoides, and C. nuecensis; and 3) the remaining annual, C. wrightii. The cpDNA data suggest that, although the perennial habit is primitive within the section, the annual species of section Coreopsis have likely not originated from an extant perennial species. The estimated proportion of nucleotide differences per site (given as 100p) for the cpDNAs of species in the section ranges from 0.00 to 0.20, which is comparable to or lower than values reported for other congeneric species. The low level of cpDNA divergence is concordant with other data, including cross compatibility, interfertility and allozymes, in suggesting that species of the section are not highly divergent genetically.     

Growth of Octopine-Catabolizing Pseudomonas spp. under Octopine Limitation in Chemostats and Their Potential To Compete with Agrobacterium tumefaciens

The growth characteristics of five octopine-catabolizing pseudomonads have been determined in batch and continuous cultures. All five strains belonged to rRNA homology group I and showed a more psychrotrophic growth pattern than did Agrobacterium tumefaciens B6 and ATCC 15955. In chemostats limited by octopine, either as the source of carbon and nitrogen or the sole source of nitrogen, maximum specific growth rates and substrate affinities were lower than those in chemostats limited by glutamate. These growth dynamics were similar to those observed for Agrobacterium strains B6 and ATCC 15955 even though the catabolic genes and pathways are believed to be different in the two genera. An analysis of the yields in octopine-limited chemostats indicated that the use of octopine as the sole source of carbon and nitrogen was grossly inefficient. Octopine and presumably lysopine and octopinic acid provided a better source of nitrogen than of carbon. One of the Pseudomonas fluorescens strains, E175D, was able to produce its highest yield on octopine as a nitrogen source. Competition models formulated on pure culture parameters indicated that two of the Pseudomonas spp. would dominate A. tumefaciens B6 and ATCC 15955 when in simple competition for octopine as a limiting substrate.     

Decidual cell reaction induced by prostaglandin F2α in the mature oöphorectomized rat

Summary Sprague-Dawley rats were oöphorectomized and after a 2–3 week recovery period were given daily injections of progesterone (2.0 mg/0.1 ml) for six consecutive days. On the fourth day of progesterone treatment 0.2 mg of estradiol 17 was given in addition and the right uterine cornua were subjected to one of five experimental maneuvers. On the sixth day of progesterone treatment the uterine cornua were weighed and processed for light and electron microscopy. The weights of all left cornua (84.6 +- 3.7 mg) and the right cornua of PBS-injected (93.3 +- 11.5 mg) and sham operated uteri (83.6 +- 19.8 mg) were comparable. A significant increase (p<0.001) in weight was found in cornua that received PGF₂ (144 +- 6.7 mg), PGF₂ with mild local trauma (scratch) (146 +- 28.0 mg), and scratch alone (162 +- 12.7 mg). The majority of cornua treated by scratch alone, or by PGF₂ with or without scratch, showed a decidual cell reaction by light microscopy and had a significantly higher mitotic index than those treated with saline, or by sham operation. When specimens were evaluated for the presence of the OCR, the highest rank was found in tissues treated by scratch alone or by PGF₂ with or without scratch. Morphometric evaluation by light microscopy indicated that the extent of decidualization in PGF₂-treated tissue was comparable to that of scratchtreated tissue. Ultrastructural observation of PGF₂-treated tissue revealed that decidual cells closely resembled those treated with scratch. However, electron microscopic morphometry revealed that cells that responded to PGF₂ had higher volume and surface densities of organelles associated with metabolic activity than did cells responding to scratch alone. These results demonstrate that locally administered PGF₂ can initiate, in the hormonally prepared mature oöphorectomized rat, a DCR comparable to that induced by local trauma.     

Purification and characterization of two β-N-acetylhexosaminidases from the tobacco hornworm,Manduca sexta (L.) (Lepidoptera: Sphingidae)

β-N-Acetylhexosaminidases were detected in 10 insects including species of Lepidoptera, Coleoptera, Hemiptera, and Orthoptera. Two enzymes were purified from the tobacco hornworm, Manduca sexta (L.). EI was detected in larval and pharate pupal molting fluid, integument, and pupal hemolymph while EII was found in larval and pupal hemolymphs. They are acidic hydrolases with similar molecular weights (6.1 × 10⁴), molar extinction coefficients at 280 nm (1.9 × 10⁵ liters mol^?1 cm^?1), and pH optima (pH 6). They differ in the number of polypeptide chains per molecule (EI is a single chain and EII consists of two polypeptide chains), amino acid composition, extent of glycosylation (EII is probably a glycoprotein), isoelectric point (pI_EI = 5.9 and pI_EII ～- 5.1), tissue distribution, and reactivities toward nitrophenylated N-acetylglucosamine (k_cat,I = 328 s^?1 and k_cat,II = 103 s^?1) and N,N′-diacetylchitobiose (k_cat,I = 307 s^?1 and k_cat,II = 3 s^?1). These results suggest that EI is a chitinase and that EII may function as a hexosaminidase in vivo.     

Analysis of ribosome binding sites from the s1 message of reovirus: Initiation at the first and second AUG codons

Two ribosome-protected initiation sites from the s1 message of reovirus have been characterized. Comparison of these sites with the previously determined sequence of s1 mRNA (Li et al., 1980) reveals that wheat germ ribosomes select and protect the first two AUG triplets in that message. This is unusual, since ribosomes initiate at a single site, the 5′-proximal AUG, in almost all other eukaryotic messenger RNAs that have been examined. The first AUG codon in s1 mRNA is preceded by a pyrimidine in position ?3, thus distinguishing it from most other eukaryotic messages, which have a purine (usually A) in that position. The behavior of s1 mRNA is consistent with the hypothesis that flanking nucleotides modulate the efficiency with which the migrating 40 S ribosomal subunit recognizes an AUG codon as a stop signal. If the first AUG triplet is flanked by suboptimal sequences, as in s1 mRNA, some 40 S ribosomes bypass that site and initiate at the next AUG downstream. The second AUG in the s1 message conforms to the consensus sequence (A-N-N-A-U-G-G) for eukaryotic initiation sites.     

BIOCHEMICAL COMPOSITION AND PHOTOSYNTHETIC CARBON METABOLISM OF NUTRIENT LIMITED CULTURES OF MERISMOPEDIA TENUISSIMA (CYANOPHYCEAE)1

Continuous cultures of Merismopedia tenuissima Lemmerman, limited by phosphorus, nitrogen, sulfur, or carbon, were compared to non limited batch cultures by two methods. The cellular content of photosynthetic pigments (chlorophyll and phycocyanin) was found to decrease in all nutrient limited cultures, except for the carbon limited culture. The ratio of carbohydrate to protein was 4- to 7-fold higher in P, N or S limited cultures than in non-limited or C limited cultures. The macromolecular products of photosynthesis were determined in samples to which NaH¹⁴CO₃ was added. Relative incorporation into protein decreased in P or N limited cultures, increased accumulation of low molecular weight compounds was found in S and P limited cultures, and little change was noted in C limited cultures as compared to non-limited cultures. Although relative incorporation into protein was significantly greater at 20μEin·m^?2·s^?1 light intensity than at 180 μEin·m^?2.s^?1 in non-limited cultures, this effect was abolished in all nutrient limited cultures. These results suggest that measurement of the cellular carbohydrate to protein ratio and the products of photosynthesis would be useful in the analysis of algal population dynamics in nature.     

Isolation of 2'',3''-Cyclic Nucleotide 3''-Phosphodiesterase from Human Brain

Abstract: The enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase (EC 3.1.4.37) has been isolated from an acetone powder of human subcortical white matter. The yield was about 11 mg from 28 g of powder and a specific activity of 213 unitdmg protein was obtained using 2',3'-cyclic CMP as the substrate. A major protein band of molecular weight approx. 96,000 was found by gel electrophoresis under nonreducing conditions. However, two distinct protein bands of molecular weight 46,000 ± 1400 and 48,000 ± 1400 were observed when the protein sample was reduced with 10 mM-dithiothreitol and subjected to electrophoresis in more restrictive 12-15% polyacrylamide-SDS gels. This molecular weight is lower than that previously reported for the bovine enzyme. Antibodies against the purified human enzyme have been raised in New Zealand white rabbits.     

Nocturnal loss of muscle protein from House sparrows (Passer domesticus)

An overall loss of protein was considered to be the explanation for at least some of the observed loss of lean dry material from muscle of wild House sparrows overnight.