Carbon flux and growth in mature deciduous forest trees exposed to elevated CO2

Whether rising atmospheric carbon dioxide (CO2) concentrations will cause forests to grow faster and store more carbon is an open question. Using free air CO2 release in combination with a canopy crane, we found an immediate and sustained enhancement of carbon flux through 35-meter-tall temperate forest trees when exposed to elevated CO2. However, there was no overall stimulation in stem growth and leaf litter production after 4 years. Photosynthetic capacity was not reduced, leaf chemistry changes were minor, and tree species differed in their responses. Although growing vigorously, these trees did not accrete more biomass carbon in stems in response to elevated CO2, thus challenging projections of growth responses derived from tests with smaller trees.     

Evaluation of upper respiratory tract function during strenuous exercise in racehorses

Forty-six racehorses with a history of poor performance underwent endoscopic evaluation of laryngeal and pharyngeal function while exercising on a high-speed treadmill. This evaluation allowed the definitive diagnosis of intermittent or continual upper respiratory tract obstruction as a cause of poor performance, as well as the documentation of the dynamic functional anatomy of the obstruction. Ten of the horses (22%) were determined to have a functional abnormality of the upper respiratory tract. These abnormalities included epiglottic entrapment (1 horse), persistent dorsal displacement of the soft palate during exercise (4 horses), and left laryngeal hemiplegia (5 horses). Thirty-two horses were observed to have signs of left laryngeal hemiparesis (asynchronous arytenoid movement) at rest that did not impair full laryngeal abduction during strenuous exercise.     

The production of N-nitrosoiminodiacetate from nitrilotriacetate and nitrate by microorganisms growing in mixed culture

Mixed populations of microorganisms growing in a recycling soil percolator produced N-nitrosoiminodiacetate (NIDA) after 30 days growth using sodium nitrilotriacetate (NTA), a detergent additive, and NaNO₃ as C and N source respectively. Control experiments using autoclaved soil or substituting either acetate (C source) or NH⁺₄ (N source) did not show any N-nitroso derivative production. Five distinct strains of microorganisms were isolated which could grow on an NTA/NO^?₃ minimal medium but none produced NIDA in pure culture. Mixed cultures of two strains of Pseudomonas produced NIDA after 4 days percolation, using glass beads as a support. Cell-free extracts of the mixed cultures synthesized NIDA after 30 min incubation at 30°C with an activity of 27 μmoles NIDA produced/mg protein h^?1. Physical separation of the two organisms and the cell-free extracts by a dialysis membrane in a chamber determined that only one of the two organisms was responsible for the synthesis of NIDA, but the production was dependent upon the presence of the other organism. The possible relationship between the two organisms is discussed.     

The physical appearance of the vulva in ureaplasma infected ewes

The vulvar labia of ewes naturally infected with ureaplasma were significantly more swollen and red than those of uninfected ewes. Similar changes were observed following experimental infection of previously uninfected ewes. These differences, although statistically significant, were not sufficiently marked to be useful in diagnosing infection by clinical examination.     

Chemically induced sterility in wheat for hybrid seed production

Summary The gametocidal effects of RH-531, RH-532, and RH-2956 were studied with three rates and times of foliar application on two spring wheat (Triticum aestivum L.) varieties, Anza and Yecora 70. RH-531 and RH-532 applied at or before booting stage caused rather large reduction in plant height while RH-2956 had a small effect on height. Application of any of the three chemicals on Anza at meiotic stages reduced self-pollination (SP) fertility by 97–99%. If 90% SP fertility reduction is acceptable, the application time could vary from premeiosis to postmeiosis for Anza. Yecora 70 was less sensitive than Anza to gametocide treatments. The lowest SP fertility obtained in Yecora 70 with RH-531, RH-532, and RH-2956 was by treatment at booting (4 kg/ha), at premeiosis (2 kg/ha), and heading (8 kg/ha), and the corresponding SP fertility reductions were 74, 89, and 71%. Pollen stainability-determined by aceto-carmine, IKI, and Alexander's stains-was not affected by gametocide treatment and was not useful in evaluating sterility induced by these chemicals. For the RH-531-treated Anza and Yecora 70 and the RH-532-treated Anza, more than 94% of the seeds produced by open-pollination on treated plants were from self-or sib-pollination as determined by progeny testing. However, RH-532-treated Yecora 70 and RH-2956-treated Anza and Yecora 70 did result in more crossed seeds, with a maximum of 20% outcrossing. It was believed that spike compactness induced by the chemicals and the related poor flower opening were the major limitations for outcrossing. Artificial pollinations made to the test varieties showed that RH-531 induced both male and female sterility and was undesirable for practical use. RH-532, however, could be applied at the booting stage to avoid severe female sterility, and RH-2956 clearly was the best of the three chemicals, with the female fertility very close to those of the untreated checks of both Anza and Yecora 70. Of the three chemicals, RH-2956 gave the highest percentage of hybrid plants in the progeny of hand-or open-pollinated spikes. Its practical use for hybrid seed production, however, will depend largely on improvement of methods to increase cross pollination in wheat.     

Breeding for Highly Fertile Isolates of Nectria haematococca MPVI that are Highly Virulent on Pea and In Planta Selection for Virulent Recombinants

ABSTRACT The heterothallic ascomycete Nectria haematococca mating population VI (anamorph Fusarium solani) is a broad host range pathogen. Field isolates of this fungus that are pathogenic on pea tend to be female sterile, of low fertility, and the same mating type (MAT-1), whereas female fertile isolates of either mating type that are highly fertile tend to be nonpathogenic on this plant. To facilitate genetic analysis of traits that may be important in the ability of N. haematococca to parasitize peas, a breeding project was undertaken to produce hermaphroditic isolates of each mating type that are highly fertile and highly virulent on peas. Although the association of high virulence on peas with female sterility and the MAT-1 mating type was not completely broken, isolates with high fertility and high virulence on peas were bred within two generations. Highly virulent progeny were also isolated by an alternative method in which pea plants were inoculated with a mixture of ascospores from a cross between two moderately virulent parents. Whereas all ascospores isolated without selection in planta had lower virulence than the parents, many isolates recovered from diseased tissue were more virulent than the parental isolates. Some of the recovered isolates were shown by restriction fragment length polymorphism analysis to be genetic recombinants of the parents, demonstrating that the pea tissue selected virulent recombinants. All highly virulent isolates tested had the ability to detoxify the pea phytoalexin pisatin, again showing a link between this trait and pathogenicity on the pea.     

Evaluation of Bacillus thuringiensis Berliner as an alternative control of small hive beetles, Aethina tumida Murray (Coleoptera: Nitidulidae)

Small hive beetles, Aethina tumida Murray, are parasites and scavengers of honeybee colonies, Apis mellifera L., and have become an invasive species that can cause considerable damage in its new distribution areas. An effective subspecies of Bacillus thuringiensis Berliner (=Bt) would provide an alternative to chemical control of this pest. Therefore, we tested three different Bt strains [B. thuringiensis, var. aizawai (B401^®), B. thuringiensis var. kurstaki (Novodor^®) and B. thuringiensis var. San Diego tenebrionis (Jackpot^®)] and Perizin^® (3.2% coumaphos), each applied on combs with a pollen diet fed to pairs of adult beetles. This evaluates the products for the suppression of successful small hive beetle reproduction. While none of the tested Bt strains showed a significant effect on the number of produced wandering larvae, we could confirm the efficacy of coumaphos for the control of small hive beetles. We further show that it is also efficient when applied with a lower concentration as a liquid on the combs. We suggest the continued search for efficient Bt strains naturally infesting small hive beetles in its endemic and new ranges, which may become a part of the integrated management of this pest.