Effects of auditory stimuli on the lifespan of Drosophila melanogaster

It is well known that music can have calming effects on humans, other mammals and birds. Reducing environmental stress or enhancing the resistance to certain stressors has been shown to extend lifespan in several organisms. Evidence also suggests that mild temporary stress may also enhance stress resistance and ultimately slow the aging process. This study explored the possibility that music may influence the lifespan of the fruit fly Drosophila melanogaster, possibly by affecting responses to stress. Flies received either background sounds (control), or background sounds supplemented with music (experimental). The experimental group had classical music playing constantly at an average of 20 dB above background sound. The median lifespan of females receiving music was 42 days compared to the median of 45 days without music, but the difference was not significant. For males median lifespans were 42 days with music exposure, and 47 days without music and the difference was significant. These results suggest that exposure to classical music decreased the lifespan of male Drosophila. Both experimental and control populations showed age-dependent increases in mortality, indicating that music affects the normal aging process rather than showing overt toxicity. These results suggest that certain auditory stimuli may be stressful and can be used as insect management.     

Marcescence and senescence in a submediterranean oak (Quercus subpyrenaica E.H. del Villar): photosynthetic characteristics and nutrient composition

We have studied some characteristics of marcescent leaves (withered retained leaves) and senescent leaves in Quercus subpyrenaica, a tree species that plays a major role in the climatic transition forests between temperate and mediterranean environments in north-eastern Spain. Leaves were taken from the upper and lower halves of the tree crown, both in the south- and north-exposed parts of the tree. Leaves receiving low photosynthetic photon flux density (PPFD) undergo autumnal senescence, which is associated with decreases in photosynthetic pigments and decreases in the chlorophyll a to chlorophyll b ratio. Leaves receiving higher PPFD underwent senescence at a later date. Leaves situated in the upper, south-exposed part of the tree, which receive the highest PPFD, showed no signs of senescence and remained photosynthetically active for a longer period of time, marcescence occurring suddenly at the end of the season. Marcescence is unlikely to cause an improvement in nutrient recycling, since the removal of nutrients proceeded similarly in marcescent and senescent leaves. Marcescence may increase the time-span of the assimilation capacity for a significant period of time during September and October, when high light intensities and mild temperatures occur. The phenomena triggering marcescence may be related to low temperatures.     

How in vitro light affects growth and survival of ex vitro cassava

Cassava is one of the most important food crops in Africa. Meristem culture is an effective method of eliminating viruses and other systemic diseases spread through the vegetative propagation of stems. However, in semi‐arid conditions, survival of ex vitro plants in the field is often disappointing. When an increasing range of light regimes in vitro was provided, the fresh and dry masses more than doubled their values between 29 and 369 mmol s^?1 m^?2 PPFDs. Increases in numbers of senescent leaves and stem thickness were also recorded with increasing PPFD. However, PPFD above 101 mmol s^?1 m^?2 resulted in 30–70% reduction in plant survival, with the thin plants with the smallest fresh and dry masses being the ones with highest survival rates. High light and temperature levels in the greenhouse were also found to be critical for plant survival. It was also shown that transpirational loss from detached leaves and epicuticular wax deposits were not good indicators for predicting survival of ex vitro cassava plantlets during acclimatisation.     

Insect immune priming: ecology and experimental evidences

1. Immune priming refers to improved protection of the host after a second encounter with the same parasite or pathogen. This phenomenon is similar to that of adaptive immunity in vertebrates. 2. There is evidence to suggest that this improved protection can be species/strain‐specific and can protect organisms for a lifetime. These two attributes, along with a biphasic immune response, are essential characteristics of immune priming and form the basis for the effectiveness of resistance to parasites and pathogens. 3. This paper considers the effect of immune priming within and across generations, the influence of a heterologous challenge during immune priming and the importance of testing the immune response with natural pathogens. 4. The analysis presented takes into account the multifaceted nature of the invertebrate immune response. The lack of evidence suggesting that the bacterial microbiome plays a complementary role in the immune priming outcome is discussed. 5. Finally, the cost of immune priming is explored. This is a poorly investigated issue, which could help to explain why there is a paucity of evidence in support of immune priming.     

Bone histological correlates of high-frequency flapping flight and body mass in the furculae of birds: a phylogenetic approach

A parsimony optimization of the presence of high-frequency flapping flight onto a phylogeny of 29 species of birds shows that this is a derived character state that has been acquired at least four independent times: by the last common ancestor of Alcidae, that of Podicipedidae, that of Anatidae, and that of Rallidae. Cineradiographic analysis has shown that the furculae of birds underwent extraordinary deformations during the wingbeat cycle. Cyclical deformations are known to produce microfractures in the bone tissue, which may be a stimulus for Haversian remodelling, a mechanism of resorption and reconstruction of bone tissue that may repair bone microdamage. In the present study, we performed a comparative analysis in a phylogenetic context to test the effect of the frequency of cyclical deformations and body mass on the rate of Haversian remodelling in the furculae of birds. A variation partitioning analysis showed that the type of flight (high-frequency flapping flight vs. other kinds of flight of lower wing beat frequency) and body mass explained a significant portion of Haversian bone density (the outcome of Haversian remodelling) and that the phylogeny also explained a significant part of this variation. This phylogenetic signal on Haversian bone density variation may be the outcome of phylogenetic signal on the proximate causes producing Haversian remodelling.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 729–738.     

Heterozygote excess in ancient populations of the critically endangered Dioon caputoi (Zamiaceae,Cycadales) from central Mexico

Dioon caputoi is a long‐lived cycad known from only four populations that range in size from 50 to 120, mostly adult individuals. Dioon caputoi has the most narrow geographical range of all Dioon spp. (less than 10 km), existing completely within the boundaries of the Tehuacán–Cuicatlán Biosphere Reserve, Mexico. Negative inbreeding values were found in all four populations (F_IT = ?0.242) and within subpopulations (F_IS = ?0.379). Only c. 10% of the total genetic variation was partitioned among populations (F_ST = 0.099). We also found that most mean values of genetic variation (A = 1.91 ± 0.12; P = 78.9 ± 10.2; H_E = 0.35 ± 0.01) are within the range reported for other Dioon species with larger populations and with wider geographical ranges. These results support recent findings that rare plant species maintain high levels of genetic diversity. The heterozygote excess found at all loci is discussed in detail from a neutral evolutionary perspective, leaving arguments as working hypotheses for further research. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 436–447.     

Systematic revision of the Late Miocene sabre‐toothed felid Paramachaerodus in Spain

Abstract: A systematic revision of the sabre‐toothed cat genus Paramachaerodus  Pilgrim, 1913 is presented. Two species are recognized within Paramachaerodus, Pa. orientalis, and Pa. maximiliani, and the genus Promegantereon  Kretzoi, 1938 is retrieved to include Promegantereon ogygia. Material from the Turolian Spanish localities of Crevillente‐2 (MN 11, Alicante) and Las Casiones (MN 13, Teruel), which was previously assigned to Paramachaerodus, is now included in the tribe Metailurini. The exceptional discoveries at the Spanish Vallesian (MN 10, Madrid) fossil site of Batallones‐1 have made it possible to characterize the dentition and cranial anatomy of a previously very poorly known machairodontine cat, formerly included in Paramachaerodus as Pa. ogygia, which now can be distinguished from Pa. orientalis and Pa. maximiliani by the following features: canines without crenulations, P3 with a marked disto‐lingual expansion, P4 without ectostyle and with a well‐developed protocone, M1 bucco‐lingually elongated and double‐rooted, m1 with a larger talonid, and primitive mandible morphology. Thus, the population from Batallones‐1 constitutes a clearly different form from the genus Paramachaerodus, and we propose its inclusion in the genus Promegantereon  Kretzoi, 1938 , together with an upper canine from Crevillente‐2 (MN 11), very similar to those from Batallones‐1. In contrast, Pa. orientalis shows the following apomorphies: crenulated canines, P3 reduced in size and without disto‐lingual expansion, P4 with a clear ectostyle as well as a reduced, backwardly displaced protocone and with a rounded and single‐rooted M1. The species Pa. maximiliani is characterized by its slightly larger size, crenulated canines, very elongated P3 with a moderate disto‐lingual expansion and P4 and M1 similar to those of Pa. orientalis. Paramachaerodus orientalis is recorded at Puente Minero (MN 11, Teruel), Concud (MN 12, Teruel), Crevillente‐15, and Crevillente‐16 (both MN 12, Alicante), and Paramachaerodus maximiliani in Venta del Moro (MN 13, Valencia). The available data suggest that Pr. ogygia was present in the Iberian Late Vallesian and Early Turolian faunas (MN 10 and MN 11) but disappeared after that age. Paramachaerodus was present in the faunas throughout the Turolian, with the species Pa. orientalis and Pa. maximiliani, this latter being probably part of the same immigration event that occurred in the Late Turolian and involved other mammal taxa such as camelids and ursids.