Effects of pre-severance light quality on the vegetative propagation ofEucalyptus grandis W. Hill ex Maiden

Two-leaf, two-node cuttings were taken fromEucalyptus grandis stockplants grown under different light qualities (red to far-red ratios of 0.4, 0.7, 1.3, 3.5 and 6.5) at a constant photon flux density (200 μmol m^-2 s^-1). Two experiments tested effects of pre-severance light quality on cutting morphology, post-severance gas exchange, carbohydrate status and rooting of cuttings. The best rooting percentage was achieved by cuttings with longer stems and greater stem volume from stockplants grown at lower red to far-red (R∶FR) ratios. Generally, rooting success was associated with low pre-severance starch and water-soluble sugar concentrations, and a greater total water-soluble carbohydrate (TWSC) content per cutting. Rooting was associated with well maintained stem starch and an increase in stem TWSC during the propagation period. Gas exchange of cuttings was measured between 28 and 33 days after severance. Rooting percentages at 35 days after severance were positively and linearly related to net photosynthetic rate and stomatal conductance. In unrooted cuttings there was a net release of CO₂ which increased significantly with an increase in pre-severance R∶FR ratio. These results demonstrate that stockplant environment may significantly modify the morphology and physiology of subsequent cuttings, and that cutting morphology, and stored and current photosynthates have a significant influence on rooting. ITE is a component of the Edinburgh Centre for Tropical Forestry     

Development of an expanded bed technique for an affinity purification of G6PDH from unclarified yeast cell homogenates

The use of an expanded bed of STREAMLINE Red H-7B for the purification of the intracellular glycolytic enzyme glucose 6-phosphate dehydrogenase (G6PDH) directly from untreated preparations of disrupted yeast cells has been investigated. Small-scale experiments, carried out in packed beds, have shown that the optimal pH for adsorption is 6.0 and have enabled optimization of elution conditions using a series of eluents. The dynamic capacity of the adsorbent for G6PDH was determined in a small expanded bed to be 28 units/mL. These results were used to develop a preparative scale separation of G6PDH in a STREAMLINE 50 expanded bed column. G6PDH was purified directly from an unclarified yeast homogenate in 99% yield with an average purification factor in the eluted fraction of 103. Cleaning-in-place (CIP) procedures using 0.5 M NaOH and 4M urea in 60% (v/v) ethanol have demonstrated that the adsorbent can be regenerated with no loss of adsorption capacity of alteration of bed expansion characteristics after many cycles of operation. (c) 1995 John Wiley & Sons, Inc.     

The life and work of Eugenie Clark: devoted to diving and science

Synopsis Eugenie Clark is an ichthyologist with a talent for communicating about marine life. Her life had three principal periods, (1) studies under Charles Breder, Carl Hubbs, Lester Aronson and Myron Gordon, (2) directorship of the Cape Haze Marine Laboratory sponsored by the Vanderbilts, and (3) professorship and inspired teaching at the University of Maryland. Genie proved that sharks have surprising learning abilities and that, contrary to popular opinion, none are vicious killers. During her studies on reproductive behavior, territoriality, and ecology of tropical marine sand-dwelling fishes of the Caribbean and Red seas, among many other phenomena, she discovered the cross-fertilizing hermaphroditeSerranus subligarius, the Moses and peacock soles producing toxins that repel sharks and other predators, and sharks sleeping in underwater caves in Mexico and Japan. She combined a love for swimming and diving with the study of marine fishes - from hard-hat diving and snorkeling to using SCUBA and submersibles. Professor emerita since 1992, she has ridden whale sharks and participated in dives using submersibles to 3 600 m depths. She is a recipient of over 25 honors and awards, participated in 24 television specials, and the current IMAX film on sharks. She is the author of theLady with a Spear andThe Lady and the Sharks which are of considerable popular fame.     

THE SIGNIFICANCE OF OUTCROSSING IN AN INTIMATE PLANT-HERBIVORE RELATIONSHIP. I. DOES OUTCROSSING PROVIDE AN ESCAPE FROM HERBIVORES ADAPTED TO THE PARENT PLANT?

Sexual reproduction may be advantageous for hosts that are preyed on or parasitized by enemies that are highly adapted to them. Sexual reproduction can create rare genotypes that may escape predation by virtue of rarity and can create variable progeny that may escape predation if enemies are specialized to only one genotype of host. Populations of the herbivorous thrips, Apterothrips apteris, have been shown to be adapted to individual Erigeron glaucus clones. Here, we show that thrips adapted to the parental clone could better use plant progeny of the “home” clone produced through selfing than progeny derived from selfing of other clones. Thus, despite recombination, progeny produced by selfing presented a resource that was similar to the parental phenotype with respect to use by adapted thrips. We also show that E. glaucus susceptibility to thrips has a genetic basis and then ask whether outcrossing provides a means for E. glaucus clones to escape attack by adapted thrips. When we compared the success of thrips on progeny produced by selfing or outcrossing of the home clone, we found that the merits or disadvantages associated with outcrossing were dependent on the susceptibility to infestation of the parental clones. Selfing by clones characterized by low infestations of thrips appeared to preserve resistant genotypes; all outcrossed progeny had, on average, higher infestation levels than selfed progeny. In contrast, outcrossed progeny of clones characterized by high infestations of thrips had either the same thrips density as progeny from selfing, when the pollen donor was a highly infested clone, or lower density, when the pollen donor was a low infestation clone. The advantages of outcrossing were caused by the alleles contributed to progeny rather than to progeny variability or rarity.     

Small fish, big fish, red fish, blue fish: size-biased extinction risk of the world's freshwater and marine fishes

Aim  In light of the current biodiversity crisis, there is a need to identify and protect species at greatest risk of extinction. Ecological theory and global-scale analyses of bird and mammal faunas suggest that small-bodied species are less vulnerable to extinction, yet this hypothesis remains untested for the largest group of vertebrates, fish. Here, we compare body-size distributions of freshwater and marine fishes under different levels of global extinction risk (i.e. listed as vulnerable, endangered or critically endangered according to the IUCN Red List of Threatened Species ) from different major sources of threat (habitat loss/degradation, human harvesting, invasive species and pollution).
Location  Global, freshwater and marine.
Methods  We collated maximum body length data for 22,800 freshwater and marine fishes and compared body-size frequency distributions after controlling for phylogeny.
Results  We found that large-bodied marine fishes are under greater threat of global extinction, whereas both small- and large-bodied freshwater species are more likely to be at risk. Our results support the notion that commercial fishing activities disproportionately threaten large-bodied marine and freshwater species, whereas habitat degradation and loss threaten smaller-bodied marine fishes.
Main conclusions  Our study provides compelling evidence that global fish extinction risk does not universally scale with body size. Given the central role of body size for trophic position and the functioning of food webs, human activities may have strikingly different effects on community organization and food web structure in freshwater and marine systems.     

Distribution and phylogeography of Blanford’s Fox,Vulpes cana (Carnivora: Canidae), in Africa and the Middle East

The distribution of Vulpes cana in the extreme eastern Sahara is described on the basis of new photographic and sight records, as well as a recently acquired specimen from south-eastern Egypt. The proven range of this elusive fox now extends about 1000 km south into Africa along the Red Sea coastal mountains. The proven and predicted distribution ranges of this fox are discussed. Its phylogeography and evolutionary relationship to other foxes of the region are gleaned from analysis of mitochondrial cytochrome b DNA sequence and are discussed in light of climatic and paleogeographic history of the area. The results show that the species could have initially moved into Africa during the Pliocene-Pleistocene transition period when several land bridges occurred across the Gulf of Suez. More recent land bridges between the mountains of the Sinai Peninsula and the Eastern Desert of Egypt seem to have developed and disappeared several times during the Pleistocene, possibly allowing genetic exchange between V. cana populations in these two areas. The last of this population exchange and genetic flow between the two areas seems to have ended some 14,000 years ago when the present Gulf of Suez inundation took place.     

Ultrastructure of cell division in the marine red algaLomentaria baileyana

Summary Mitosis in the marine red algaLomentaria baileyana (Rhodymeniales, Rhodophyta) was studied with the electron microscope. Nucleus associated organelles known as polar rings (PRs) migrate to establish the division poles at prophase. At prometaphase, shallow invaginations in the nuclear envelope (NE) form on two sides of each PR and soon rupture. The gaps that are consequently formed contain several small fragments of NE. A larger region of NE remains intact between the two gaps. By metaphase several cisternae of perinuclear endoplasmic reticulum (PER) have enclosed most of the nucleus but remain absent from the polar regions. The nucleolus disperses partially and a typical metaphase plate of chromosomes is formed. Each PR has disjoined into separate proximal and distal portions. MTs converge widely on all regions of the polar area, but do not extend into the cytoplasm. Some MTs end near or at the chromosomes while others extend slightly farther past the chromosomes or diagonally to the NE. As chromosomes move to opposite poles at anaphase, they are accompanied by nucleolar material. An interzonal midpiece (IZM) is created as the pole to pole distance increases and the NE remains intact except for the polar gaps. Following detachment from the IZM, the daughter nuclei are separated by a large central vacuole as a cleavage furrow develops and eventually constricts to form two cells following pit connection formation. It is suggested that mitosis inLomentaria represents an evolutionary intermediate between that seen in the higher and lower groups of red algae. This conclusion is in agreement with conventional morphological and light microscopic criteria used to placeLomentaria in theRhodymeniales, which is considered to be the next to most advanced order in theRhodophyta.     

Flexistipes sinusarabici,a novel genus and species of eubacteria occurring in the Atlantis II Deep brines of the Red Sea

Four isolates of a gram-negative flexible bacterium have been obtained from brine water samples of the Atlantis II Deep of the Red Sea at a depth of 2000 m. One isolate (MAS 10) was studied in detail. Cells are nonmotile, flexible rods, measuring about 0.3 m in width and 5 to 50 m in length. The new organisms are heterotrophs growing anaerobically on yeast extract, meat extract, peptone, tryptone, and, less efficiently, on acetate and casamino acids. Growth occurs between 30% and 53°C at pH 6 to 8 in the presence of at least 3% NaCl. The shortest doubling time is 8.5 h under optimal growth conditions. Cells are sensitive to the antibiotics penicillin, ampicillin, vancomycin, and streptomycin, but resistant to tetracyclin and rifamipicin. The GC-content of the DNA is 39 mol%. Based on their 16S rRNA the new isolates group with the general cluster of eubacterial phyla. Since they show no specific relationship to any of them, a new genus is described, which is named Flexistipes, the flexible stick. Type species is Flexistipes sinusarabici strain MAS 10 (DSM 4947).     

Viability and infectivity of protoscolices of Echinococcusmultilocularis stored at different temperatures

Survival of protoscolices of Echinococcus multiocularis removed from the intermediate host was studied at constant temperatures. The longest survival time was 16 days at 12°C when the protoscolices were stored within the cyst mass. The infectivity of the protoscolices in the decayed intermediate host was also studied. The carcasses harboring hydatid cysts were fed to dogs and a red fox on the 7th and 14th days after killing. Tapeworms were recovered from all these canines. The results indicate that the protoscolices in the decayed carcasses keep their infectivity for more than 2 weeks and suggest that the saprophagy of canines may be epidemiologically important for the transmission of E. multilocularis.     

Cytoplasmic incompatibility following somatic cell fusion inGriffithsia pacifica Kylin,a red alga

Summary Somatic cell fusion between two isolates ofG. pacifica is followed by a cytoplasmic incompatibility reaction (CIR) in the cytoplasm donated by only one of the isolates. This CIR is characterized by the aggregation, fusion and lysis of chloroplasts of the sensitive strain; the chloroplasts of the other strain are unaffected. In addition, the nuclei of both strains retain a normal distribution during the fusion and lysis events. Cell elongation and nuclear division stop in CIR-affected cells. The CIR begins in the hybrid cell and then appears sequentially in adjacent cells of the sensitive strain; this transfer occurs only between living cells which share a crosswall. There is a lag between hybrid cell formation and the initiation of the CIR. This lag is more than 3 times as long at 17 C than at 24 C; over this range, the rate of movement of the CIR along a filament is temperature-insensitive. Thus it appears that a temperature dependent process, perhaps the synthesis of CIR-inducing agents, is required for the initiation of the CIR; subsequent movement of such agents appears to occur by diffusion.Abbreviations CIR Cytoplasmic incompatibility reaction - HC hybrid cell - 1st SC first shoot cell - 2nd SC second shoot cell - 3rd SC third shoot cell - Pac-PP Puerto Penasco isolate - Pac-BC British Columbia isolate This research was supported in part by National Science Foundation Grant PCM 7823240 to SDW; NICHD Developmental Biology Training Grant ST 32 HDO 71835, Traineeship to DJK and a State of Washington Graduate Opportunities for Women and Minorities to DJK.