Response of pondcypress growth rates to sewage effluent application

Cores were collected from dominant pondcypress trees growing in a swamp that had received sewage effluent for 7 yr and a nearby control swamp to determine the combined effects of changes in nutrient supply and hydrologic regime on tree growth. The cores were used to measure two indices of tree growth: basal area increment (BAI) and relative basal area increment (RBAI, which accounts for differences in growth due to the size of teh tree) between 1970–1983 while one swamp remained untreated and the other received weekly additions of sewage effluent from 1974–1981. Throughout the whole period, the mean BAI and RBAI of pond-cypress trees in the untreated swamp remained unchanged, ranging between 5.55–6.38 cm² yr^–1 and 1.09–1.27% yr^–1, respectively. In contrast, trees in the treated swamp increased their BAI approximately two-fold from 7.40 cm² yr^–1 prior to treatment to 14.83 cm² yr^–1 after the onset of treatment and maintained this rate of growth in the 2 yr period after cessation of treatment. Relative basal area increment showed a similar response, but the proportional increase due to treatment was less (1.5-fold factor) than for BAI. The response of pondcypress trees to the sewage effluent differed depending upon whether the trees were located in the deep or shallow water zones. Trees in the deep zone of the treated swamp had lower BAIs and RBAIs than those in the shallow zone during the treatment period, whereas in pre- and post-treatment periods growth indices were equal in both zones. No significant differences in growth between deep and shallow zones were observed during all three time periods in the control swamp.     

α1-Adrenergic Receptor Mediates Arachidonic Acid Release in Spinal Cord Neurons Independent of Inositol Phospholipid Turnover

The alpha 1-adrenergic receptor has been shown to mediate the release of arachidonic acid in FRTL5 thyroid cells and MDCK kidney cells. In primary cultures of spinal cord cells, norepinephrine stimulated release of arachidonic acid (from neurons only) and turnover of inositol phospholipids (from neurons and glia) via alpha 1-adrenergic receptors. These two responses were dissociated by treatment with phorbol ester and pertussis toxin, which inhibited production of inositol phosphates with no appreciable effect on release of arachidonic acid. Extracellular calcium was required for release of arachidonic acid, but not for production of inositol phosphates. The calcium channel blockers nifedipine and verapamil inhibited release of arachidonic acid only. However, 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), a compound that blocks intracellular calcium release, diminished production of inositol phosphates, but had little effect on release of arachidonic acid. These results suggest that alpha 1-adrenergic receptors couple to release of arachidonic acid in primary cultures of spinal cord cells by a mechanism independent of activation of phospholipase C, possibly via the activation of phospholipase A2.     

Somaclonal variation inLolium multiflorum L. andL. temulentum L.

Tiller-derived callus ofLolium multiflorum L. gave rise to 65 regenerants displaying variation in height, flowering time, chromosome number and alteration to the banding pattern of the isoenzyme superoxide dismutase. Plants were also regenerated from callus cultures initiated from immature embryos of the related inbreeding speciesLolium temulentum L. Progeny of the regenerated plants from this species displayed variation in height, flowering date, ear length and chlorophyll content.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - BAP 6-benzylaminopurine     

Polymorphic repetitive DNA sequences in Mycobacterium tuberculosis detected with a gene probe from a Mycobacterium fortuitum plasmid

Clinical isolates of Mycobacterium tuberculosis were shown by Southern blotting to contain DNA sequences hybridizing to a probe derived from a Mycobacterium fortuitum plasmid. Two such M. tuberculosis DNA fragments, isolated from a gene library, were used as probes to show restriction fragment length polymorphism in M. tuberculosis strains by detecting a repetitive sequence apparently located at different points on the chromosome. This could indicate the presence of a transposable element in M. tuberculosis which is partly homologous to a region of the M. fortuitum plasmid. The probes described can be used to fingerprint M. tuberculosis isolates, and in addition are capable of distinguishing M. tuberculosis from Mycobacterium bovis and BCG.     

Allozyme variation and differentiation in African and Indian rhinoceroses

We studied variation at 25 to 31 allozymic loci in African and Asian rhinoceroses. Four taxa in three genera were examined: African Ceratotherium simum simum (northern white rhinoceros), C. s. cottoni (southern white rhinoceros), Diceros bicornis (black rhinoceros), and Rhinoceros unicornis (Indian rhinoceros). Extremely small amounts of intraspecific variation were observed in sample sizes of 2 to 10 presumably unrelated individuals per taxon: P = .00-.10, H = 0.00-0.02. We examined demographic bottlenecks and sampling errors as possible reasons for the low levels of detectable variation. The very small intraspecific genetic distance (D = 0.005) between the two living white rhinoceros subspecies is far less than the distance that has been reported for other mammal subspecies. The mean D value of 0.32 +/- 0.11 between the two African genera was also less than expected given the divergence time of greater than 7 million years suggested by the fossil record. Rhinoceroses may be evolving more slowly at the structural gene loci than are some other mammal groups. The estimate of D = 1.05 +/- 0.24 for the African-Indian split supports this idea, as the lineage diverged at least 26 million years ago. Our results contribute to the currently available scientific information on which management decisions aimed toward saving endangered rhinoceroses should be based.     

The effects of phosphate supply on growth of plants from the Brasilian Cerrado: experiments with seedlings of the annual weed,Bidens gardneri Baker (Compositeae) and the tree,Qualea grandiflora (Mart.) (Vochysiaceae)

Summary Plants of the cerrado tree species Qualea grandiflora and the annual herb Bidens gardneri were grown from seed in controlled environment rooms at 30/20° C and 12 hour photoperiod. Seedlings were grown in pots or small tubes containing sand and provided with various amounts of mineral solutions based on the formulation of Hoagland and Arnon but with the phosphate content modified in some cases. In a long-term experiment lasting 213 days, plants supplied with full strength Hoagland's solution all died but plants of Qualea given 1/10 strength solution survived, although they grew very slowly. Low relative growth rates (0.008–0.036 d^–1) were also a feature of other experiments with Qualea and calculated rates of net assimilation rate gave values of 3–7 mg CO₂ dm^–2 h^–1. Expansion of the photosynthetic surface proceeded slowly and the cotyledons were the main site of photosynthesis for more than 40 days. The low rates of growth occurred despite significant uptake of phosphorus by young plants and in shortterm experiments growth was independent of the amount of phosphate supplied and accumulated. In contrast, the values of R found for plants of Bidens reached 0.24 d^–1. Growth of young plants was dependent on the external supply of phosphorus, being reduced when this was low and also when it was very high. Growth of the photosynthetic surface was also much more rapid than for Qualea and also varied with supply of phosphorus. The results are discussed in the context of the occurrence of these species in the Cerrado.     

Evidence that actin reinforces the extensible hyphal apex of the oomyceteSaprolegnia ferax

Summary Filamentous actin in the apices of growing hyphae of the oomyceteSaprolegnia ferax is distributed such that it could compensate for weakness in the expanding apical cell wall and thus play a role in morphogenesis of the tip. The tapered extensible portion of the hyphal tip where the cell wall is plastic contains a cap of actin which differs in organization from the actin in subapical, inextensible regions of the hypha. Rapidly growing hyphae which are expected to have a longer plastic cell wall region contain longer actin caps. Furthermore, the weakest point in the hyphal apex, demonstrated by osmotic shock-induced bursting, was within the taper where the wall is plastic but never in the extreme apex where actin was most densely packed and presumably the strongest. Treatment of hyphae with cytochalasin E/dimethyl sulphoxide induced rapid changes in actin caps. Cap disruption was accompanied by transient growth rate increases, subsequent rounding and swelling of apices and a shift of osmotically induced burst points closer to the apex. These correlated changes are consistent with a role for the actin cap in tip morphogenesis. The association between regions of plasticity in the apical cell wall, the extent of the actin cap, the location of the weakest point in the apex and the effects of damage to the actin cap suggest that the cap functions to support the apex in regions where the cell wall is weak.Abbrevations CE cytochalasin E - DMSO dimethyl sulphoxide - RP rhodamine phalloidin Dedicated to the memory of Professor Oswald Kiermayer     

Temporal and spatial correlation of fertilization current, calcium waves and cytoplasmic contraction in eggs of Ciona intestinalis

Eggs of the ascidian Ciona intestinalis were loaded with the calcium indicator fura-2 via whole-cell clamp electrodes and changes in cytoplasmic calcium and cell currents were monitored during fertilization either in separate eggs or simultaneously in the same egg. The first indication of egg activation was the fertilization current; which reached peak values around 1 nA after 30 s. A wave of elevated calcium was detectable between 5 s and 30 s (mean = 21 s) after the start of the fertilization current. This wave spread across the egg increasing cytoplasmic calcium levels to at least 10 microM. When the fertilization current and calcium wave were complete and cytoplasmic calcium levels were decreasing to prefertilization levels, a cortical contraction wave spread across the egg surface. In eggs showing normal fertilization current, the calcium wave and the contraction wave were in the same direction. A region of elevated calcium persisted at the animal pole. Changing cytoplasmic calcium levels locally by local application of ionophore A23187 caused a contraction wave originating at the site of ionophore application. Increasing cytoplasmic calcium uniformly by facilitating calcium entry through voltage-regulated channels did not result in a contraction wave.     

Presence of the bacterial hemoglobin gene improves α-amylase production of a recombinantEscherichia coli strain

A recombinant plasmid (pMK57) was constructed by cloning theBacillus stearothermophilus α-amylase gene into pUC8; plasmid pMK79 was then derived from pMK57 by inserting the bacterial (Vitreoscilla) hemoglobin gene into the latter plasmid. Both pMK57 and pMK79 were transformed intoEscherichia coli strain JM103 to make strains MK57 and MK79, respectively. Both MK57 and MK79 produced α-amylase and MK79 produced hemoglobin. MK79 outgrew MK57 in shake flasks in LB medium, the advantage of the former appearing in late log phase. MK79 produced more α-amylase than MK57, on both per cell and per volume bases, in both mid and late log phases; the maximum advantage of MK79 (on a per volume basis) occurred in late log phase, at which time it produced 3.3 times as much α-amylase as MK57. The numbers of copies per cell of both pMK57 and pMK79 were significantly lower than that of pUC8.