Thyrotrophin in the pars tuberalis triggers photoperiodic response

Molecular mechanisms regulating animal seasonal breeding in response to changing photoperiod are not well understood. Rapid induction of gene expression of thyroid-hormone-activating enzyme (type 2 deiodinase, DIO2) in the mediobasal hypothalamus (MBH) of the Japanese quail (Coturnix japonica) is the earliest event yet recorded in the photoperiodic signal transduction pathway. Here we show cascades of gene expression in the quail MBH associated with the initiation of photoinduced secretion of luteinizing hormone. We identified two waves of gene expression. The first was initiated about 14 h after dawn of the first long day and included increased thyrotrophin (TSH) beta-subunit expression in the pars tuberalis; the second occurred approximately 4 h later and included increased expression of DIO2. Intracerebroventricular (ICV) administration of TSH to short-day quail stimulated gonadal growth and expression of DIO2 which was shown to be mediated through a TSH receptor-cyclic AMP (cAMP) signalling pathway. Increased TSH in the pars tuberalis therefore seems to trigger long-day photoinduced seasonal breeding.     

SLAM (CDw150) is a cellular receptor for measles virus

Measles virus continues to be a major killer of children, claiming roughly one million lives a year. Measles virus infection causes profound immunosuppression, which makes measles patients susceptible to secondary infections accounting for high morbidity and mortality. The Edmonston strain of measles virus, and vaccine strains derived from it, use as a cellular receptor human CD46 (refs 3, 4), which is expressed on all nucleated cells; however, most clinical isolates of measles virus cannot use CD46 as a receptor. Here we show that human SLAM (signalling lymphocyte-activation molecule; also known as CDw150), a recently discovered membrane glycoprotein expressed on some T and B cells, is a cellular receptor for measles virus, including the Edmonston strain. Transfection with a human SLAM complementary DNA enables non-susceptible cell lines to bind measles virus, support measles virus replication and develop cytopathic effects. The distribution of SLAM on various cell lines is consistent with their susceptibility to clinical isolates of measles virus. The identification of SLAM as a receptor for measles virus opens the way to a better understanding of the pathogenesis of measles virus infection, especially the immunosuppression induced by measles virus.     

Insect signalling: components of giant hornet alarm pheromone

Up to 74 people die each year in Japan after being stung by Hymenopteran insects, with hornets (Vespa spp.) being among the worst offenders. Here we identify a volatile, multi-component alarm pheromone in the venom of the world's largest hornet, V. mandarinia, and use field bioassays to show that 2-pentanol is its principal active component, and that 3-methyl-1-butanol and 1-methylbutyl 3-methylbutanoate act synergistically with it. The compound 1-methylbutyl 3-methylbutanoate, which may also be a foraging-site-marking pheromone, elicits a strong defensive reaction in the sympatric prey hornet V. simillima xanthoptera. As these chemicals are sometimes used in food flavourings and as fragrances in cosmetics, it is possible that they might provoke a seemingly unwarranted hornet attack on humans.     

Binding of a non-beta-lactam antibiotic to penicillin-binding proteins

In the search for new beta-lactam antibiotics of natural origin, the discoveries of cephamycins and sulfazecins (monobactams) were important turning points in that they accelerated many screening efforts aimed at other new compounds. In our target-directed screening for beta-lactam antibiotics using beta-lactam hypersensitive mutants, we have examined Gram-negative bacteria isolated from natural habitats and have recently reported several types of beta-lactam antibiotics such as cephabacins and formadicins. Here we report a novel antibiotic, lactivicin, found using this system. Although lactivicin has various biological activities commonly observed in beta-lactam antibiotics, it does not possess a beta-lactam ring in its molecule, but has the unique structure of a dicyclic dipeptide.     

Reciprocal autoregulation of blood flow and blood pressure

Zusammenfassung Der Eingangswiderstand verschiedener Arterien wurde im Niederfrequenzbereich (0,0005 bis 0,25 Hz) mittels sinusförmig modulierter Pumpen-Perfusion mit arteriellem Blut an narkotisierten Hunden gemessen. Die Resultate lassen die Existenz zweier reziprok wirkender Autoregulationsmechanismen vermuten, deren Frequenzcharakteristik mit Hilfe eines einfachen linearen Modells simuliert werden konnte.

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Supported by NIH Grant No. HE 11747.     

Oriental orchid (Cymbidium pumilum) attracts drones of the Japanese honeybee (Apis cerana japonica) as pollinators.

The discovery that drones of the Japanese honeybee (Apis cerana japonica) pollinate the oriental orchid (Cymbidium pumilum) is reported. Drones are attracted to the orchid flower aroma mainly during their mating flights in April through May. Some drones cluster on the flower racemes and others insert their heads deep into the flowers. Drones with pollinia on their scutellum visit other orchids, which facilitates pollination. Individual workers and swarming colonies are also strongly attracted by the flower aroma, but the allopatric western honeybee (Apis mellifera) is not attracted.