Alloreactive T-cell recognition of bovine major histocompatibility complex class II products defined by one-dimensional isoelectric focusing

T-cell recognition of bovine MHC (BoLA) class II antigens was investigated in relation to BoLA class II polymorphisms defined by one-dimensional isoelectric focusing (1D-IEF). One-way mixed lymphocyte reactions (MLRs), and allospecific cell lines and clones were used. In general, T-cell responses correlated with the 1D-IEF defined haplotypes (EDF types). However, with MLRs some responses appeared to be associated with BoLA class I differences. All combinations of responder-stimulator pairs produced alloreactive T-cell responses both in MLR and in generation of allolines/clones. Thus allospecific lines and clones were generated to all EDF types tested. Splits in the IEF typing were observed with EDF6 and EDF3, indicating that distinct BoLA class II haplotypes are not necessarily distinguished by 1D-IEF alone. Furthermore, the patterns of reactivity with EDF3 expressing cells were complex with the T-cell specificities splitting EDF3 into several distinct types. Also, in some cases it was clear that more than one T-cell specificity per EDF type was detectable. Thus, allospecific lines and clones provide complementary and additional information to the 1D-IEF typing for polymorphism of the BoLA class II complex. This extra information is particularly important in terms of the functional significance of the BoLA complex for antigen presentation and immune response gene effects.     

Root and shoot growth of semi-dwarf and taller winter wheats

Investigations are reported of root and shoot growth in semi-dwarf and taller winter wheat varieties grown in contrasting soils over three years. Comparisons were made of the distribution with depth of roots, estimated by injecting rubidium-86 into stem bases and counting the content in soil cores. The relative ability to absorb phosphate from different zones was measured from the recovery in aerial parts of ³²P injected into the soil at different depths. The distribution of dry matter in roots and aerial parts, and total root length, was measured using soil cores and samples of aerial parts taken during the growth of the crop. Relative growth rates of the aerial parts followed a sigmoid curve, but those of the roots showed little change between germination and anthesis. There was little evidence of varietal differences in root growth, though there was some indication that at depth the roots of the semi-dwarf varieties were more extensive and absorbed more phosphate than those of the taller varieties.     

Hormonal Control of Molting and Reproduction in Ticks

SYNOPSIS. Among ticks there are two developmental and threereproductive patterns that correlate with taxonomic groupings(Argasidae, prostriate and metastriate Ixodidae). Feeding isa prerequisite for molting; feeding and mating are necessaryfor reproduction in all except a few parthenogenetic species.Growth and development in ticks and other chelicerates appearto be controlled by molting hormones (ecdysteroids), as theyare in insects and crustaceans. Ecdysone and 20-hydroxyecdysoneappear to be present in most or all of the major cheliceratetaxa. Epidermis is the site of ecdysone production and fat bodythe site of 20-hydroxylation in the argasid Ornithodoros parkeri,as is probably the case in all ticks. Ecdysteroids influenceearly stages of spermatogenesis by stimulation of DNA synthesisin spermatocytes, but controls for later stages of meiosis areunknown. A polypeptide (12,000 daltons) from male genital accessoryglands stimulates capacitation (maturation) of spermatids intosperm at the time of spermatid transfer to females. Knowledgeof control of egg development and oviposition is incomplete.Stimuli from the synganglion are necessary for completion ofoogenesis and two synganglial factors have been proposed. AnEgg Development Stimulation Factor (EDSF) in O. parkeri is synthesizedand/or released three to six days after feeding. VitellogenesisInducing Factor (VIF) in O. moubata is synthesized and/ or releasedwithin one hour after feeding. The VIF is hypothesized to impactan unidentified tissue which in turn produces a Fat Body StimulationFactor (FSF) that stimulates fat body to synthesize vitellogenin(Vg). Roles of ecdysteroids and juvenile hormones during eggdevelopment and oviposition are unclear.     

ULTRASONIC VOCALIZATIONS AND THEIR ASSOCIATIONS WITH THE NON-VOCALIZATION BEHAVIOUR OF THE ENDANGERED TURKISH SPINY MOUSE ACOMYS CILICIUS SPITZENBERGER IN A CAPTIVE POPULATION

ABSTRACT

Although ultrasonic vocalizations (USVs) have been recorded in many species of rodent and in various contexts, e.g. sexual behaviour and aggression, it has not been demonstrated for the endangered Turkish Spiny Mouse Acomys cilicius Spitzenberger. This study investigated whether A. cilicius emits USVs and, if so, how these USVs associated with non-vocalization behaviour. Ultrasonic recording equipment was set up for 12 days in an off-exhibit enclosure of A. cilicius at Bristol Zoo. At least seven different types of USV were recorded. For eight of the 12 study days, ultrasonic and video recording equipment were run concurrently. From these observations it was found that emission of USVs were associated with sexual behaviour, aggression and social investigation. The results of this study show for the first time that captive A. cilicius produce USVs that resemble those produced by other rodent species, including its close relative the Egyptian Spiny Mouse A. cahirinus Desmarest. As these findings apply only to a captive Turkish Spiny Mouse population, additional work should be carried out to investigate the behaviour and USV production in the wild in addition to further research on captive populations investigating the apparent communicative function of these vocalizations.     

Analysis of Proteins Binding to the ITAM Motif of the β-Subunit of the High-Affinity Receptor for IgE (FcεRI)

Aggregation of the multichain (α β γ₂) high-affinity IgE receptor (Fcε RI) initiates a signaling cascade that results in the release of allergic mediators. The cytoplasmic tails of the Fcε RI-β and -γ subunits contain immunoreceptor tyrosine-based activation motifs (ITAMs). Phosphorylation of the γ ITAM mediates activation of Syk kinase and is sufficient for triggering the responses induced by Fcε RI crosslinking. Phosphorylation of the β ITAM is insufficient to mediate cell activation. The rat β ITAM contains three tyrosines (Tyr²¹⁸, Tyr²²⁴, and Tyr²²⁸) with an intermediate noncanonical tyrosine. Synthetic peptides based on the ITAM of the Fcε RI-β subunit were used to investigate the role of each phosphotyrosine in the binding of signaling proteins to this motif. Among the proteins that bind to phosphorylated β ITAM are Syk, Grb2, Shc, SHIP, and SHP-1, and binding does not depend on previous cell activation. Nonphosphorylated peptides do not bind these proteins. Syk binding to β -peptides is dependent on the number and position of phosphotyrosines in the ITAM. Phosphorylation of Tyr²¹⁸ seems to be most important for Syk binding. Recruitment of Syk and other signaling proteins to the β -subunit might be important for its amplifier role.     

Metabolic acclimation to excess light intensity in Chlamydomonas reinhardtii

There are several well‐described acclimation responses to excess light in green algae but the effect on metabolism has not been thoroughly investigated. This study examines the metabolic changes during photoacclimation to high‐light (HL) stress in Chlamydomonas reinhardtii using nuclear magnetic resonance and mass spectrometry. Using principal component analysis, a clear metabolic response to HL intensity was observed on global metabolite pools, with major changes in the levels of amino acids and related nitrogen metabolites. Amino acid pools increased during short‐term photoacclimation, but were especially prominent in HL‐acclimated cultures. Unexpectedly, we observed an increase in mitochondrial metabolism through downstream photorespiratory pathways. The expression of two genes encoding key enzymes in the photorespiratory pathway, glycolate dehydrogenase and malate synthase, were highly responsive to the HL stress. We propose that this pathway contributes to metabolite pools involved in nitrogen assimilation and may play a direct role in photoacclimation. Our results suggest that primary and secondary metabolism is highly pliable and plays a critical role in coping with the energetic imbalance during HL exposure and a necessary adjustment to support an increased growth rate that is an effective energy sink for the excess reducing power generated during HL stress.     

Spatial variation in the magnitude and functional form of density‐dependent processes on the large skipper butterfly Ochlodes sylvanus

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