A Response Surface Analysis of the Effects of Cyclohexanecarboxylic Acid and 2,4-Dichlorophenoxy Acetic Acid on Nitrogen Metabolism in Phaseolus vulgaris L.

Primary leaves of 2-week-old bush bean plants (Phaseolus vulgariscv ‘Top Crop’) were treated with one of 36 combinationsof cyclohexanecarboxylic acid (CHCA) and 2,4-dichlorophenoxyacetic acid (2,4-D), each at six equally spaced concentrationsFive, 7, 9 and 11 days after treatment, one plant from eachcombination was harvested, and primary leaves were monitoredfor nitrate reductase activity (NRA), nitrate nitrogen (N) concentration,organic N concentration, and d wt NRA was assayed by an in vivoprocedure Data from the resulting 6 x 6 x 4 factorial configuration foreach of the four responses were analysed using the method oforthogonal polynomials, which is described in detail This method,based on equally spaced levels, produced independent polynomialexpressions in CHCA concentration, 2,4-D concentration, and/ortime-to-harvest after treatment, which were then fitted to thedata on each response by simple linear regression analyses.A graphical procedure was used to compare predicted responsesfrom the best fit equations with the actual data. Examination of computer-generated plots of the three-dimensionalresponse surfaces revealed that NRA, organic N concentration,and d wt decreased with increasing 2,4-D concentration, whereasnitrate N content increased Increasing CHCA concentration generallyhad the opposite effect on NRA and nitrate N content, althoughinteraction between the two chemicals was evident in the latterresponse Organic N content remained unchanged as CHCA concentrationincreased, while d wt first increased then decreased Possibleexplanations for these results are discussed, as are the advantagesof using factorial designs with equally-spaced levels in plantgrowth studies. Phaseolus vulgaris L, bush bean, nitrogen metabolism, plant growth regulators, cyclohexanecarboxylic acid, 2,4-dichlorophenoxy acetic acid, regression analysis, orthogonal polynomials, response surfaces analysis     

Seasonal variation in freezing tolerance of the New Zealand alpine cockroach Celatoblatta quinquemaculata

1. The cold hardiness of the alpine cockroach Celatoblatta quinquemaculata was investigated. This species is found at 1360 m a.s.l. beneath schist slabs on the Rock and Pillar Range (Central Otago, New Zealand). Cockroaches were collected monthly from January to December 1996, and their LT₅₀ and supercooling points determined.
2. Celatoblatta quinquemaculata was freezing tolerant throughout the year, with a lower lethal temperature in winter of – 8.9 °C. Celatoblatta quinquemaculata was also found frozen under rocks in the field when the under-rock temperature was below – 3 °C, and could survive being frozen at – 5 °C for 4 days in the laboratory.
3. There was a marked decrease in LT₅₀ temperature from – 5.5 °C in April to – 7.5 °C in May. This coincides with decreasing temperatures from summer through autumn to winter, during which temperatures beneath snow-covered rocks may reach – 7.3 °C.
4. Supercooling points fluctuated during the year, with an increase from – 4.2 °C in autumn to – 3.4 °C in winter. Supercooling point was highest in spring, and changes in supercooling point do not appear to be related to changes in LT₅₀.
5. Recordings of environmental temperatures from the Rock and Pillar Range suggest that cockroaches may undergo up to twenty-three freeze–thaw cycles in the coldest month of the year, and that they may remain frozen for periods of up to 21 h. Maximum cooling rates recorded in the field (0.01 °C min^–1) were 100-fold slower than laboratory cooling rates, so survival estimates from laboratory experiments may be underestimates.     

House Finch Carpodacus mexicanus roosting behaviour during the non-breeding season and possible effects of mycoplasmal conjunctivitis

We studied House Finch Carpodacus mexicanus roosting behaviour during the non-breeding season using radiotracking and direct observations in Ithaca, NY, USA. In contrast to what has been reported in the literature and in contrast to what should be expected from Newton's European studies of cardueline finches, House Finches roost in small groups (mean 3.5; maximum 11) and do not display at roost sites. Seventy-seven per cent of the birds re-used the same tree on successive observations. In winter, birds re-used the same roost tree more often than in the autumn, and birds with mycoplasmal conjunctivitis tended to move more between roost trees than did birds without conjunctivitis. A small number of radiotagged birds that roosted in the same tree were observed together in the daytime more often than by chance, suggesting the existence of social bonds between birds (some same sex) during the non-breeding season. In the autumn the birds often roosted in leafed deciduous trees and closer to their daytime feeding locations than they did in winter. In winter all birds roosted in evergreen trees. It is possible that the reliable and predictable food sources at feeding sites offered by the public might have changed House Finch roosting behaviour.     

Systematics of the spider genera Mallos and Mexitlia (Araneae, Dictynidae)

This systematic study recognizes and describes 14 species of the genus Mallos O. Pickard-Cambridge, 1902 and three species of the genus Mexitlia Lehtinen, 1967. Three species of Mallos – Mallos gertschi, Mallos chamberlini and Mallos macrolirus –and one species of Mexitlia – Mexitlia altima –are newly described. Mallos ghiggi (Caporiacco, 1938) is considered a synonym of Mexitlia grandis (O. Pickard-Cambridge, 1896). Mexitlia grandis is considered the senior synonym of Mexitlia avara (Banks, 1898). Two species, Mallos jlavovittatus (Keyserling, 1880) and Mallos nigrescens (Caporiacco, 1955) are removed from Mallos. The males of Mallos kraussi Gertsch, 1946 and Mallos blandus Chamberlin and Gertsch 1958, are described for the first time. A cladistic analysis based on 26 morphological characters produced a cladogram that supports the monophyly of Mallos and the validity of Mexitlia. This cladogram presents a phylogenetic framework for considering the evolution of social behaviour in Mallos.     

Isolation and characterization of microsatellites in the woody shrub,Calothamnus quadrifidus (Myrtaceae)

Microsatellite loci were developed for genetic analysis of the bird pollinated woody shrub Calothamnus quadrifidus. A genomic library was constructed and screened with dinucleotide and trinucleotide repeat sequences. Ten dinucleotide microsatellite markers were developed, and polymorphism in a population of C. quadrifidus was investigated for six of these markers, which showed an average of 12.7 alleles per locus. Mendelian inheritance of the loci was confirmed through analysis of open pollinated progeny arrays of 10 plants. These loci will be used to study gene flow patterns between isolated populations of this species in southwest Western Australia.     

Trophic level asynchrony in rates of phenological change for marine,freshwater and terrestrial environments

Recent changes in the seasonal timing (phenology) of familiar biological events have been one of the most conspicuous signs of climate change. However, the lack of a standardized approach to analysing change has hampered assessment of consistency in such changes among different taxa and trophic levels and across freshwater, terrestrial and marine environments. We present a standardized assessment of 25 532 rates of phenological change for 726 UK terrestrial, freshwater and marine taxa. The majority of spring and summer events have advanced, and more rapidly than previously documented. Such consistency is indicative of shared large scale drivers. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. Less coherent patterns in some groups of organisms point to the agency of more local scale processes and multiple drivers. For the first time we show a broad scale signal of differential phenological change among trophic levels; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services.