Do men yawn more than women?

The aim of this study was to test the hypothesis that sex differences in primate yawning are related to size dimorphism in canine teeth. Data were collected on yawning by a primate species (Homo sapiens) in which the two sexes differ only slightly in canine size. Unlike more dimorphic primates, human males and females did not differ in the frequency of yawning, although uncovered yawns were more frequent in men than in women.     

Do American born Japanese children still grow faster than native Japanese?

Growth patterns of Japanese schoolchildren in Hawaii, composed of 2,954 boys and 3,213 girls aged between 11 and 17, were compared with those comparable groups of Japanese schoolchildren in Japan based on the data published by the Japanese Ministry of Education. Growth characteristics studied were height, weight, and relative weight index, weight/(height). The Hawaii-Japanese boys were taller at early ages but the difference disappeared by age 16. Native Japanese girls were shorter than Hawaii-Japanese until age 13, but they overtook the latter by age 14, exceeding them in height after age 15. A similar pattern was found in weights of girls but the Hawaii-Japanese boys remained consistently heavier by 5.0 to 9.0 kg than native Japanese. The relative weight measure indicated that the Hawaii boys were more "obese" than native Japanese boys for the growth period studied; whereas the same tendency was maintained until age 15 in girls. These observations indicate a marked degree of convergence of the patterns of physical growth of the two populations, whose differences were unmistakably in favor of American born children in earlier studies. It is concluded that the convergence is due largely to the improved environmental conditions in Japan in recent years.     

Do bonobos copulate more frequently and promiscuously than chimpanzees?

The copulatory activities of bonobos (Pan paniscus) of Wamba, Zaire, were compared with those of chimpanzees (P. troglodytes schweinfurthii) of Mahale, Tanzania. The copulation rates of adult male bonobos were equal to or lower than those of adult male chimpanzees. The copulation rates of adult female bonobos were approximately equal to those of adult female chimpanzees who were in maximal genital swelling, but it should be much higher than those of the adult female chimpanzees throughout the birth interval. The copulation rates of adolescent male bonobos were lower than those of adolescent male chimpanzees, whereas the copulation rates of adolescent female bonobos were much higher than those of adolescent female chimpanzees. It was suggested that the bonobos of Wamba did not copulate more promiscuously than did the chimpanzees of Mahale. The female bonobos may show “receptivity”, whereas female chimpanzees may show rather “proceptivity”.     

Do scale-free regulatory networks allow more expression than random ones?

In this paper, we compile the network of software packages with regulatory interactions (dependences and conflicts) from Debian GNU/Linux operating system and use it as an analogy for a gene regulatory network. Using a trace-back algorithm we assemble networks from the pool of packages with both scale-free (real data) and exponential (null model) topologies. We record the maximum number of packages that can be functionally installed in the system (i.e., the active network size). We show that scale-free regulatory networks allow a larger active network size than random ones. This result might have implications for the number of expressed genes at steady state. Small genomes with scale-free regulatory topologies could allow much more expression than large genomes with exponential topologies. This may have implications for the dynamics, robustness and evolution of genomes.     

Do single nodules of Casuarinaceae contain more than oneFrankia strain?

Summary Studies using inoculum suspensions prepared from single nodules of Casuarinaceae suggest that more than oneFrankia strain may be found in some nodules. Evidence is also presented to support the concept of intergeneric specificity in host-Frankia relations in the family Casuarinaceae.     

Do more sociable dogs gaze longer to the human face than less sociable ones?

Domestic dogs (Canis familiaris) are especially skillful in communicating with humans, and they rely on special abilities to do that. One of these skills involves gazing at human faces in cases of uncertainty or when seeking for something out of reach. In this study, we evaluated the relationship between dogs' sociability level and the ability to learn to gaze in a situation with food in sight but out of their reach. Thirty-nine adult dogs were tested in two procedures: (1) a sociability test that involved interacting with an unknown person, and (2) a learning task that consisted of training trials in which gazing at the experimenter's face was food reinforced, followed by extinction trials in which gazing was not followed by food. A significant positive correlation was found between the duration of physical contact with the unknown person in the sociability test and gaze duration during extinction. Moreover, high sociability dogs gazed significantly longer at humans during extinction trials. We discuss the possibility that, more sociable animals, such as those who pay more attention to the person in our sociability test, may be more persistent in their communicative attempts because the presence of the human is intrinsically reinforcing to them. Finally, we comment on the importance of these findings for training purposes.     

Do molecules matter more than morphology? Promises and pitfalls in parasites

Systematics involves resolving both the taxonomy and phylogenetic placement of organisms. We review the advantages and disadvantages of the two kinds of information commonly used for such inferences--morphological and molecular data--as applied to the systematics of metazoan parasites generally, with special attention to the malaria parasites. The problems that potentially confound the use of morphology in parasites include challenges to consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence. Molecular characters such as DNA sequences present an alternative data source and are particularly useful when not all the parasite's life stages are present or when parasitaemia is low. Nonetheless, molecular data can bring challenges that include troublesome DNA isolation, paralogous gene copies, difficulty in developing molecular markers, and preferential amplification in mixed species infections. Given the differential benefits and shortcomings of both molecular and morphological characters, both should be implemented in parasite taxonomy and phylogenetics.     

ER targeting signals: more than meets the eye?

The signal sequences that target newly synthesized proteins to the endoplasmic reticulum are highly variable; however, the functional significance of this diversity has remained obscure. In this issue, Kang et al. (2006) report that variability in signal sequences allows the cell to selectively regulate the translocation of proteins into the endoplasmic reticulum in a substrate-specific manner.     

Drosophila peripodial cells,more than meets the eye?

Drosophila imaginal discs (appendage primordia) have proved invaluable for deciphering cellular and molecular mechanisms of animal development. By combining the accessibility of the discs with the genetic tractability of the fruit fly, researchers have discovered key mechanisms of growth control, pattern formation and long-range signaling. One of the principal experimental attractions of discs is their anatomical simplicity - they have long been considered to be cellular monolayers. During larval stages, however, the growing discs are 2-sided sacs composed of a columnar epithelium on one side and a squamous 'peripodial' epithelium on the other. Recent studies suggest important roles for peripodial epithelia in processes previously assumed to be confined to columnar cell monolayers.     

F-box proteins: more than baits for the SCF?

Progression through the mammalian cell cycle is associated with the activity of four cyclin dependent kinases (Cdc2/Cdk1, Cdk2, Cdk4, and Cdk6). Knockout mouse models have provided insight into the interplay of these Cdks. Most of these models do not exhibit major cell cycle defects revealing redundancies, and suggesting that a single Cdk might be sufficient to drive the cell cycle, similar as in yeast. Recent work on Cdk2/Cdk4 double knockouts has indicated that these two Cdks are required to phosphorylate Rb during late embryogenesis. The lack of Rb phosphorylation is progressive and associated with reduced E2F-inducible gene expression. Cdk2 and Cdk4 share the essential function of coupling the G1/S transition with mitosis. However, proliferation in early embryogenesis appears to be independent of Cdk2 and Cdk4. We discuss these observations and propose molecular mechanisms that establish the requirement for Cdk2 and Cdk4 at the G1/S transition. We are considering that the balance between proliferation and differentiation is disturbed, which affects especially heart development and leads to embryonic lethality in Cdk2 ^-/- Cdk4 ^-/- mutants. We also discuss the specific functions of Cdk4 and Cdk6, which ironically do not compensate for each other.     

DHA supplementation during the perinatal period and neurodevelopment: Do some babies benefit more than others?

A dietary supply of docosahexaenoic acid (DHA, 22:6n-3) during the perinatal period is postulated to be important for the neurodevelopmental outcome of children. This paper reviews the results of two large scale intervention trials in which equivalent dietary doses of DHA were assessed. One trial assessed the ex utero effect of DHA supplementation for preterm infants born <33 weeks' gestation while the other trial assessed the in utero effect of DHA supplementation during the second half of pregnancy. Ex utero DHA supplementation, which aimed to achieve the level of DHA accumulation that would occur in the womb, appeared more effective in improving the neurodevelopmental outcome of preterm children rather than in utero DHA supplementation of unborn infants. Significant treatment by sex and treatment by birth weight interactions were noted indicating that boys and girls respond differently to DHA supplementation and that birth weight may also be important in predicating the DHA responsiveness.