“Wall-papering” and elaborate nest architecture in the ponerine antHarpegnathos saltator

Summary Excavation of 18 nests ofHarpegnathos saltator from southern India revealed an unusually complex architecture for a ponerine ant. The inhabited chambers are not deep in the ground. The uppermost chamber is protected by a thick vaulted roof, on the outside of which is an intervening space serving as isolation from the surrounding soil. In large colonies, the vaulted roof is extended into a shell which encloses several superimposed chambers. Little openings, which may be encircled by moulded flanges, occur in the upper region of the shell. The inside of the chambers is partly or completely lined with strips of empty cocoons. A refuse chamber is always found deeper than the inhabited chambers; live dipteran larvae (family Milichiidae) are typically present. These elaborate nests represent a large energetic investment, and we speculate therefore that nest emigration is unlikely in this species. Consequently, colony fission may never occur, unlike other ants where gamergates reproduce.     

Phytoplankton monitoring by flow cytometry

The application of flow cytometry to the monitoring of phytoplanktonis demonstrated. A comparison is made with conventional approachesto phytoplankton monitoring: light microscopy for the determinationof species abundance, and chlorophyll a determination and insitu chlorophyll a measurement by fluorescence for the determinationof the biomass. Flow cytometric measurements correlate wellwith these conventional types of measurements, as has been shownby comparing a full year of monitoring data obtained at a fixedmonitoring location 10 km off the Dutch coast. Flow cytometrybridges the gap between labour-intensive, but highly informative,microscopic observations and simple biomass measurements withless information content: via flow cytometry optical data areobtained at high speed for individual particles, which can betranslated into biomass information. On the basis of the flowcytometric measurements, rough discrimination of phytoplanktonspecies groups is possible, particularly for the abundant species.Of crucial importance is careful calibration of the flow cytometer,to ensure quantitative and comparable measurements over a longperiod of time. Calibration and quality assurance aspects arecovered in detail. ³Present address: Akzo Nobel Central Research Laboratories Arnhem,Department CRL, PO Box 9300, NL-6800 SB Arnhem, The Netherlands     

Trypsin inhibitor activity in mature tobacco and tomato plants is mainly induced locally in response to insect attack,wounding and virus infection

Wounding of plants by insects is often mimicked in the laboratory by mechanical means such as cutting or crushing, and has not been compared directly with other forms of biotic stress such as virus infection. To compare the response of plants to these types of biotic and abiotic stress, trypsin inhibitor (TI) activity induced locally and systemically in mature tobacco (Nicotiana tabacum L.) and tomato (Lycopersicon esculentum L.) plants was followed for 12 days. In tobacco, cutting, crushing and insect feeding all induced comparable levels of TI activity of approx. 5 nmol·(mg leaf protein)^?1 in wounded leaves, while tobacco mosaic virus (TMV) infection of tobacco induced 10-fold lower amounts in the infected leaves. In tomato, feeding by insects also led to the induction of a level of TI activity of 5 nmol·(mg leaf protein)^?1. In contrast, both cutting and crushing of tomato leaves induced 10-fold higher amounts. These data show that biotic stress, in the form of insect feeding and TMV infection, and abiotic stress, in the form of wounding, have different effects on local levels of induced TI activity in mature tobacco and tomato plants. Irrespective of the type of wounding, in neither tobacco nor tomato could systemic induction of TI activity be observed in nearby unwounded leaves, which suggests that systemic induction of TI activity in mature tobacco and tomato plants is different from systemic TI induction in seedlings. Wounding of tobacco leaves, however, did increase the responsiveness to wounding elsewhere in the plant, as measured by an increased induction of TI activity.     

Purification and characterization of CMP-N-acetylneuraminic acid hydroxylase from pig submandibular glands

N-Glycoloylneuraminic acid (Neu5Gc) is synthesized as its CMP-giycosideby the action of CMPN-acetylneuramlnic acid (CMP-Neu5Ac) hydroxylase.This enzyme is a soluble cytochrome bs-dependent monooxygenaseand has been purified to apparent homogeneity from pig submandibularglands by precipitation with N-cetyN,N,N-trimethylam-moniumbromide and fractionation on Q-Sepharose, Cibacron Blue 3GA-Agarose,Reactive Brown 10-Agarose, Hexyl-Agarose and Superose S.12.This procedure resulted in an 8960-fold purification of thehydroxylase with a recovery of 0.8%. The molecular mass of thisprotein was shown to be 65 kDa on SDS-PAGE and 60 kDa as determinedby gel filtration on Superose S.12, which suggests that theenzyme is a monomer. The purified CMP-Neu5Ac hydroxylase isactivated by FeSO₄ and inhibited by iron-binding reagents suchas o-phenanthroline, KCN, Tiron and ferro-zine. An apparentKm of 11 µM was determined for the substrate CMP-Neu5Acusing purified hydroxylase in the presence of Triton X-100-solubilizedmicrosomes. In a reconstituted system consisting of purifiedhydroxylase, cytochrome b₅, cytochrome b₅ reductase and catalase,an apparent K_m of 3 µM was measured. The apparent K_mforcytochrome b₅ in this system was 0.24 µM. Immunizationof a rabbit with enriched and purified hydroxylase led to anantiserum that inhibited CMP-Neu5Ac hydroxylase activity andreacted with the purified 65 kDa protein on a Western blot afterSDS-PAGE. Antibodies specific for this 65 kDa protein were isolatedand showed a strong reaction with the purified CMP-Neu5Ac hydroxylasefrom mouse liver after immunoblotting. Initial experiments withthis monospecific antibody suggest that the activity of thehydroxylase in a particular tissue correlates with the amountof immuno-reactive protein. cytochrome b₅ N-glcoloylneuraminic acid hydroxylase pig submandibular gland mucin sialic acid     

The phenotype of some late-flowering mutants is enhanced by a locus on chromosome 5 that is not effective in the Landsberg erecta wild-type

Late-flowering mutants that have been described in ecotypes other than Landsberg erecta (Ler) have been found to be dominant alleles of the FRI locus located on chromosome 4, which determines lateness in many very late ecotypes. The extreme lateness of dominant FRI alleles depends on dominant alleles at the FLC locus that maps on the top of chromosome 5. FLC alleles with this effect have been found in all ecotypes tested (Col, Ws, S96, Est and Li) except Ler. Most likely the same locus confers lateness to the luminidependens (ld) mutant. Genotypes with a dominant FRI allele and the monogenic recessive ld mutant are only slightly later with recessive Ler alleles at the FLC locus. Genotypes where the dominant FLC alleles are combined with FRI or with the ld mutant, are strongly responsive to vernalization, which is much less effective in the FLC-Ler background.     

The periodicities in and biometeorological relationships with bed occupancy of an acute psychiatric ward in Antwerp,Belgium

Recently, some investigators have established a seasonal pattern in normal human psychology, physiology and behaviour, and in the incidence of psychiatric psychopathology. In an attempt to elucidate the chronopsy and meteotropism in the latter, we have examined the chronograms of, and the biometeorological relationships to bed occupancy of the psychiatric ward of the Antwerp University Hospital during three consecutive calendar years (1987–1989). Weather data for the vicinity were provided by a local meteorological station and comprise mean atmospheric pressure, air temperature, relative humidity, wind speed and minutes of sunlight and precipitation/day. The number of psychiatric beds occupied during the study period exhibited a significant seasonal variation. Peaks in bed occupancy were observed in March and November, with lows in August. An important part of the variability in the number of beds occupied could be explained by the composite effects of weather variables of the preceding weeks. Our results suggest that short-term fluctuations in atmospheric activity may dictate some of the periodicities in psychiatric psychopathology.     

Characterization of IS1001, an insertion sequence element of Bordetella parapertussis.

By analysis of repetitive DNA in Bordetella parapertussis, an insertion sequence element, designated IS1001, was identified. Sequence analysis revealed that IS1001 comprised 1,306 bp and contained inverted repeats at its termini. Furthermore, several open reading frames that may code for transposition functions were identified. The largest open reading frame coded for a protein comprising 406 amino acid residues and showed homology to TnpA, which is encoded by an insertion sequence element (IS1096) found in Mycobacterium smegmatis. Examination of flanking sequences revealed that insertion of IS1001 occurs preferentially in stretches of T's or A's and results in a duplication of target sequences of 6 to 8 bases. IS1001 was found in about 20 copies in 10 B. parapertussis strains analyzed. No restriction fragment length polymorphism was observed in B. parapertussis when IS1001 was used as a probe. An insertion sequence element similar or identical to IS1001 was found in B. bronchiseptica strains isolated from pigs and a rabbit. In these strains, about five copies of the IS1001-like element were present at different positions in the bacterial chromosome. Neither B. pertussis nor B. bronchiseptica strains isolated from humans and dogs contained an IS1001-like element. Therefore, IS1001 may be used as a specific probe for the detection of B. parapertussis in human clinical samples.     

Interactive effects of rising temperatures and urbanisation on birds across different climate zones: A mechanistic perspective

Climate change and urbanisation are among the most pervasive and rapidly growing threats to biodiversity worldwide. However, their impacts are usually considered in isolation, and interactions are rarely examined. Predicting species' responses to the combined effects of climate change and urbanisation, therefore, represents a pressing challenge in global change biology. Birds are important model taxa for exploring the impacts of both climate change and urbanisation, and their behaviour and physiology have been well studied in urban and non-urban systems. This understanding should allow interactive effects of rising temperatures and urbanisation to be inferred, yet considerations of these interactions are almost entirely lacking from empirical research. Here, we synthesise our current understanding of the potential mechanisms that could affect how species respond to the combined effects of rising temperatures and urbanisation, with a focus on avian taxa. We discuss potential interactive effects to motivate future in-depth research on this critically important, yet overlooked, aspect of global change biology. Increased temperatures are a pronounced consequence of both urbanisation (through the urban heat island effect) and climate change. The biological impact of this warming in urban and non-urban systems will likely differ in magnitude and direction when interacting with other factors that typically vary between these habitats, such as resource availability (e.g. water, food and microsites) and pollution levels. Furthermore, the nature of such interactions may differ for cities situated in different climate types, for example, tropical, arid, temperate, continental and polar. Within this article, we highlight the potential for interactive effects of climate and urban drivers on the mechanistic responses of birds, identify knowledge gaps and propose promising future research avenues. A deeper understanding of the behavioural and physiological mechanisms mediating species' responses to urbanisation and rising temperatures will provide novel insights into ecology and evolution under global change and may help better predict future population responses.     

Change in climatically suitable breeding distributions reduces hybridization potential between Vermivora warblers

Aim

Climate change is affecting the distribution of species and subsequent biotic interactions, including hybridization potential. The imperiled Golden-winged Warbler (GWWA) competes and hybridizes with the Blue-winged Warbler (BWWA), which may threaten the persistence of GWWA due to introgression. We examined how climate change is likely to alter the breeding distributions and potential for hybridization between GWWA and BWWA.

Location

North America.

Methods

We used GWWA and BWWA occurrence data to model climatically suitable conditions under historical and future climate scenarios. Models were parameterized with 13 bioclimatic variables and 3 topographic variables. Using ensemble modeling, we estimated historical and modern distributions, as well as a projected distribution under six future climate scenarios. We quantified breeding distribution area, the position of and amount of overlap between GWWA and BWWA distributions under each climate scenario. We summarized the top explanatory variables in our model to predict environmental parameters of the distributions under future climate scenarios relative to historical climate.

Results

GWWA and BWWA distributions are projected to substantially change under future climate scenarios. GWWA are projected to undergo the greatest change; the area of climatically suitable breeding season conditions is expected to shift north to northwest; and range contraction is predicted in five out of six future climate scenarios. Climatically suitable conditions for BWWA decreased in four of the six future climate scenarios, while the distribution is projected to shift east. A reduction in overlapping distributions for GWWA and BWWA is projected under all six future climate scenarios.

Main Conclusions

Climate change is expected to substantially alter the area of climatically suitable conditions for GWWA and BWWA, with the southern portion of the current breeding ranges likely to become climatically unsuitable. However, interactions between BWWA and GWWA are expected to decline with the decrease in overlapping habitat, which may reduce the risk of genetic introgression.