BREEDING BEHAVIOUR OF THE GREAT WHITE EGRET

Tomlinson, D. N., S. 1976. Breeding behaviour of the Great White Egret. Ostrich 47:161-178.

The breeding displays of the Great White Egret Egretta alba are discussed but further observations are needed for statistical analysis. In support of Curry-Lindahl (1971). the ethology of the species in combination with other evidence indicates that it is more closely related to the genus Ardea than to Egretta and it is suggested that it be reclassified accordingly. In comparison with other Ardeidae. E. albu chicks are highly tolerant of each other, resulting in an estimaed high fledgling success rate.     

Humanization of Antibodies Using Heavy Chain Complementarity-determining Region 3 Grafting Coupled with in Vitro Somatic Hypermutation

A method for simultaneous humanization and affinity maturation of monoclonal antibodies has been developed using heavy chain complementarity-determining region (CDR) 3 grafting combined with somatic hypermutation in vitro. To minimize the amount of murine antibody-derived antibody sequence used during humanization, only the CDR3 region from a murine antibody that recognizes the cytokine hβNGF was grafted into a nonhomologous human germ line V region. The resulting CDR3-grafted HC was paired with a CDR-grafted light chain, displayed on the surface of HEK293 cells, and matured using in vitro somatic hypermutation. A high affinity humanized antibody was derived that was considerably more potent than the parental antibody, possessed a low pm dissociation constant, and demonstrated potent inhibition of hβNGF activity in vitro. The resulting antibody contained half the heavy chain murine donor sequence compared with the same antibody humanized using traditional methods.     

Simultaneous Surface Display and Secretion of Proteins from Mammalian Cells Facilitate Efficient in Vitro Selection and Maturation of Antibodies

A mammalian expression system has been developed that permits simultaneous cell surface display and secretion of the same protein through alternate splicing of pre-mRNA. This enables a flexible system for in vitro protein evolution in mammalian cells where the displayed protein phenotype remains linked to genotype, but with the advantage of soluble protein also being produced without the requirement for any further recloning to allow a wide range of assays, including biophysical and cell-based functional assays, to be used during the selection process. This system has been used for the simultaneous surface presentation and secretion of IgG during antibody discovery and maturation. Presentation and secretion of monomeric Fab can also be achieved to minimize avidity effects. Manipulation of the splice donor site sequence enables control of the relative amounts of cell surface and secreted antibody. Multi-domain proteins may be presented and secreted in different formats to enable flexibility in experimental design, and secreted proteins may be produced with epitope tags to facilitate high-throughput testing. This system is particularly useful in the context of in situ mutagenesis, as in the case of in vitro somatic hypermutation.     

Survival of Sclerotia of Rhizoctonia solani AG3PT and Effect of Soil‐Borne Inoculum Density on Disease Development on Potato

Sclerotia produced by a single isolate of Rhizoctonia solani AG3PT were buried in small plot experiments to investigate the effects of sclerotial production method, soil type and burial depth on sclerotial viability in field soil. The factor with the greatest effect on sclerotial viability, defined as the percentage of sclerotia germinating on agar following retrieval, in all experiments was the duration of burial. After 18 months, on average across all experiments, 20% of retrieved sclerotia were viable. A comparison between sclerotia produced in vitro on malt yeast extract agar and in vivo using micropropagated tubers in field soil found no significant differences between the two production methods on sclerotial viability. Burial in field soil at 20‐cm depth was found to significantly reduce sclerotial viability to 50% compared to 60% at 5 cm. In two pot experiments, amending the growing medium and soil with increasing inoculum densities of R. solani was found to increase stem number, stem canker and black scurf severity regardless of whether this soil‐borne inoculum was derived from mycelium or sclerotia. Black scurf incidence and severity were assessed 30–32 days posthaulm destruction and found to be similar for a range of sclerotial soil‐borne inoculum densities (1.0 × 10^?1 g/kg d.w. soil to 6 × 10^?3 g/kg d.w. soil). The significance of these findings in relation to pathogen survival, detection in soil and disease development is discussed.     

Conjugation in Hyalophysa chattoni Bradbury (Apostomatida): An adaptation to a symbiotic life cycle

Hyalophysa chattoni, borne as an encysted phoront on a crustacean's exoskeleton, metamorphoses to the trophont during the host's premolt. After the molt within 15 min to 2 h conjugants with food vacuoles appear in the exuvium, swimming along with the trophonts. Starvation in other ciliates usually precedes conjugation, but food vacuoles in conjugants do not preclude starvation. Only after ingestion and dehydration of vacuoles ceases, does digestion of exuvial fluid begin. Conjugants resorb their feeding apparatus as they fuse. A single imperforate membrane from each partner forms the junction membrane. In a reproductive cyst conjugants divide synchronously, but now the junction membrane is interrupted by pores and channels. After the last division the daughters undergo meiosis – two meiotic divisions and one mitotic division yielding two prokarya as they simultaneously differentiate into tomites. After fertilization, pairs separate and the synkaryon divides once into a macronuclear anlage and a micronucleus. Exconjugants leave the cyst and seek a host. The parental macronucleus remains active until the phoront stage when the anlage develops. Owing to random association of micronuclei during meiosis, Hyalophysa's exconjugants are more genetically diverse than exconjugants from conventional patterns of conjugation.     

How Effective Is Help on the Doorstep? A Longitudinal Evaluation of Community-Based Organisation Support

Community-based responses have a lengthy history. The ravages of HIV on family functioning has included a widespread community response. Although much funding has been invested in front line community-based organisations (CBO), there was no equal investment in evaluations. This study was set up to compare children aged 9–13 years old, randomly sampled from two South African provinces, who had not received CBO support over time (YC) with a group of similarly aged children who were CBO attenders (CCC). YC baseline refusal rate was 2.5% and retention rate was 97%. CCC baseline refusal rate was 0.7% and retention rate was 86.5%. 1848 children were included—446 CBO attenders compared to 1402 9–13 year olds drawn from a random sample of high-HIV prevalence areas. Data were gathered at baseline and 12–15 months follow-up. Standardised measures recorded demographics, violence and abuse, mental health, social and educational factors. Multivariate regression analyses revealed that children attending CBOs had lower odds of experiencing weekly domestic conflict between adults in their home (OR 0.17; 95% CI 0.09, 0.32), domestic violence (OR 0.22; 95% CI 0.08, 0.62), or abuse (OR 0.11; 95% CI 0.05, 0.25) at follow-up compared to participants without CBO contact. CBO attenders had lower odds of suicidal ideation (OR 0.41; 95% CI 0.18, 0.91), fewer depressive symptoms (B = -0.40; 95% CI -0.62, -0.17), less perceived stigma (B = -0.37; 95% CI -0.57, -0.18), fewer peer problems (B = -1.08; 95% CI -1.29, -0.86) and fewer conduct problems (B = -0.77; 95% CI -0.95, -0.60) at follow-up. In addition, CBO contact was associated with more prosocial behaviours at follow-up (B = 1.40; 95% CI 1.13, 1.67). No associations were observed between CBO contact and parental praise or post-traumatic symptoms. These results suggest that CBO exposure is associated with behavioural and mental health benefits for children over time. More severe psychopathology was not affected by attendance and may need more specialised input.     

Can tree-ring δ<Superscript>15</Superscript>N be used as a proxy for foliar δ<Superscript>15</Superscript>N in European beech and Norway spruce?

Key message

For long-term environmental investigations, tree-ring δ ¹⁵ N values are inappropriate proxies for foliar δ ¹⁵ N for both Fagus sylvatica and Picea abies under moderate N loads.

Abstract

Currently it is unclear whether stable nitrogen isotope signals of tree-rings are related to those in foliage, and whether they can be used to infer tree responses to environmental changes. We studied foliar and tree-ring nitrogen (δ¹⁵N) and carbon (δ¹³C) isotope ratios in European beech (Fagus sylvatica L.) and Norway spruce (Picea abies L.) from six long-term forest monitoring sites in Switzerland together with data on N deposition and soil N availability, as well as a drought response index over the last two decades. For both species, tree-ring δ¹⁵N and δ¹³C values were less negative compared to foliar δ¹⁵N and δ¹³C values, most likely due to recycling and reallocation of N within the tree and fractionation processes associated with the transport of sucrose and the formation of tree-rings, respectively. Temporal trends recorded in foliar δ¹⁵N were not reflected in tree-ring δ¹⁵N, with much higher variations in tree-rings compared to foliage. Soil N availability and N deposition were partially able to explain changes in foliar δ¹³C, while there were no significant correlations between environmental variables and either tree-ring or foliar δ¹⁵N. Our results suggest an uncoupling between the N isotopic composition of tree-rings and foliage. Consequently, tree-ring δ¹⁵N values are inappropriate proxies of foliar δ¹⁵N values under low-to-moderate N deposition loads. Furthermore, at such low levels of deposition, tree-ring δ¹⁵N values are not recommended as archives of tree responses to soil C/N or bulk N deposition.

     

Methods for the purification of ubiquitinated proteins

Post-translational protein modification by the covalent conjugation of ubiquitin, originally implicated as a signal for proteolytic degradation by 26S proteasome, has now been realised to play important roles in the regulation of almost all biological processes in eukaryotes. In order to understand these processes in greater detail there is a requirement for techniques that can purify mixtures of ubiquitin-conjugated proteins, as a prerequisite to their identification and characterisation. Here we review the methods that have been applied to the bulk purification of ubiquitinated proteins and discuss their applications in proteomic analyses of the 'ubiquitome'.