Melatonin in the seasonal response of the aphid Acyrthosiphon pisum

Aphids display life cycles largely determined by the photoperiod.During the warm long-day seasons.most aphid species reproduce by viviparous parthenogenesis.The shortening of the photoperiod in autumn induces a switch to sexual reproduction.Males and sexual females mate to produce overwintering resistant eggs.In addition to this full life cycle(holocycle),there are anholocyelic lineages that do not respond to changes in photoperiod and reproduce continuously by parthenogenesis.The molecular or hormonal events that trigger the scasonal response(i.c,induction of the sexual phenotypes)are still unknown.Although circadian synthesis of melatonin is known to play a key role in vertebrate photoperiodism,the involvement of the circadian clock and/or of the hor-mone melatonin in insect seasonal responses is not so well established.Here we show that melatonin levels in the aphid Acyrthosiphon pisum are significantly higher in holocyclice aphids reared under short days than under long days,while no differences were found between anholoeyelic aphids under the same conditions.We also found that melatonin is localized in the aphid suboesophageal ganglion(SOG)and in the thoracic ganglionic mass(TGM).In analogy to vertcbrates,insect-type arylalkxylamine N-acetyltransferases(i-AANATs)are thought to play a key role in melatonin synthesis.We measured the expression of four I-AANAT genes identified in A.pisum and localized two of them in situ in the insect central nervous systems(CNS).Levels of expression of these genes were compatible with the quantities of melatonin observed.Moreover,like melatonin,expression of these genes was found in the SOG and the TGM.     

Iron Deficiency Alters Discrete Proteins in Rat Caudate Nucleus and Nucleus Accumbens

Young rats (21 days old) made nutritionally iron deficient, by feeding them a semisynthetic diet containing skimmed milk for 5 weeks, had significantly lowered hemoglobin levels (5.2 +/- 4 g/100 ml). The nonheme iron content in caudate nucleus was decreased by 47%. The behavioral response of iron-deficient rats to apomorphine (2 mg/kg) and the density of 3,4-dihydroxyphenylethylamine (dopamine) D2 receptors, as measured by [3H]spiperone binding in caudate nucleus, were significantly reduced by 70 and 53%, respectively. The possibility that nutritional iron deficiency may affect protein content in brain was investigated by measuring the apparent concentration of proteins in caudate nucleus and nucleus accumbens from iron-deficient and control animals using two-dimensional gel electrophoresis. The data indicate that iron deficiency can affect content in these two brain regions. Significant changes in the content of 10 proteins were noted in the caudate nucleus and nucleus accumbens in iron-deficient rats. The albumin level was significantly increased in both regions studied, whereas the neuron-specific enolase level was increased in the nucleus accumbens and the glial fibrillary acidic protein level was reduced in the caudate nucleus. The significance of these protein content changes, as well as a reduction in content of a 94-kilodalton protein (a molecular size similar to that of the D2 dopamine receptor), remains to be established.     

Evidence of an endogenous germinant in spores of a strain of Dictyostelium purpureum

Summary In non-nutrient media and in the absence of bacteria, unwashed spores of Dictyostelium purpureum WS-321 germinated to a greater extent than did washed spores. The unidentified component(s) removed by washing stimulated germination in other populations of spores.     

Simplified Method for the Purification of S-Collidine

The use of s-collidine (2,4,6-trimethylpyridine) as a buffer for fixatives in electron microscopy was first described by Bennett and Luft (1959). Since the s-collidine contained impurities, a method was described for its purification, involving crystallization, refluxing and distillation, that made the process long and tedious. Although s-collidine of high purity can be purchased (Eastman Organic Chemicals, Polysciences), it is expensive. These facts have probably discouraged many investigators from using this compound routinely as a buffer. The procedure to be described has simplified the purification of s-collidine to filtration through a column of activated basic aluminum oxide.     

Morphogenetic Actions of 5-hydroxytryptamine and Some Analogous Substances on the Regeneration of the Planarian Worm Dugesia tigrina

The effects on regeneration of serotonin and analagous substances such as tryptamine, DMT, bufotenine, melatonin, auxin and gramine were studied on small pieces of D. tigrina. By comparison with results obtained in previous works with DOPA, α methyl DOPA and noradrenaline, and also with substances of the series of tetrahydrocannabinol it is shown that the normal morphogenetic action of the neurohormone is dependant of the presence of a free hydroxyl on a flat ring (phenol or indole) and of a free amine on the lateral chain of the molecule. Essays to detect the mechanism of the morphogenetic action did not allow to give any clear conclusion.     

Abundant DNase I-Sensitive Bacterial DNA in Healthy Porcine Lungs and Its Implications for the Lung Microbiome

Human lungs are constantly exposed to bacteria in the environment, yet the prevailing dogma is that healthy lungs are sterile. DNA sequencing-based studies of pulmonary bacterial diversity challenge this notion. However, DNA-based microbial analysis currently fails to distinguish between DNA from live bacteria and that from bacteria that have been killed by lung immune mechanisms, potentially causing overestimation of bacterial abundance and diversity. We investigated whether bacterial DNA recovered from lungs represents live or dead bacteria in bronchoalveolar lavage (BAL) fluid and lung samples in young healthy pigs. Live bacterial DNA was DNase I resistant and became DNase I sensitive upon human antimicrobial-mediated killing in vitro. We determined live and total bacterial DNA loads in porcine BAL fluid and lung tissue by comparing DNase I-treated versus untreated samples. In contrast to the case for BAL fluid, we were unable to culture bacteria from most lung homogenates. Surprisingly, total bacterial DNA was abundant in both BAL fluid and lung homogenates. In BAL fluid, 63% was DNase I sensitive. In 6 out of 11 lung homogenates, all bacterial DNA was DNase I sensitive, suggesting a predominance of dead bacteria; in the remaining homogenates, 94% was DNase I sensitive, and bacterial diversity determined by 16S rRNA gene sequencing was similar in DNase I-treated and untreated samples. Healthy pig lungs are mostly sterile yet contain abundant DNase I-sensitive DNA from inhaled and aspirated bacteria killed by pulmonary host defense mechanisms. This approach and conceptual framework will improve analysis of the lung microbiome in disease.