Dominance Acquisition During Mammalian Social Development: The "Inheritance" of Maternal Rank

We first review the suite of general problems mammals confrontduring their social development, and then focus on the specificproblem of how group-living mammals acquire their social rank.In particular, we examine maternal rank "inheritance" (MRI)in those mammals for which maternal rank is the primary determinantof female rank. This occurs in many primates and in spottedhyenas. Young primates and spotted hyenas usually attain theiradult status in two stages: they first attain ranks correlatedwith those of their mothers in peer interactions, and subsequentlychallenge and outrank older conspecifics subordinate to theirmothers. Observational learning may be necessary, but is notsufficient, for MRI. In some primates, but not hyenas, youngstersappear to learn their ranks from direct aggression against themby higher-ranking adults. Third-party support appears to promoteMRI in all species examined: the probability and style of maternalinterventions on behalf of infants often vary with rank, andboth kin and nonkin frequently form coalitions that may assistjuveniles during rank reversals.     

松梢蚧

松梢蚧又称松针蚧,是同翅目珠蚧科松蚧属专寄生在松树针叶上的害虫。由于它发生起始于松树梢头的新针叶,有些地区的群众称它为松梢蚧,表达了它发生的特点。松树受害严重的可使枝梢上的针叶大部脱落,影响松树生长。 在我国浙江早已发现中华松梢蚧(Matsucoccus sinensis Chen)。Ferris(1950)重新描述了在昆明云南松上采到的所谓中华松梢蚧。我们研究了从昆明采集的标本,发现它不是中华松梢蚧,而是一个新种。Ferris的鉴定和重新描述,很容易引起对中华松梢蚧的误解。     

Fat, Energy and Mammalian Survival

Adipose tissue plays a critical role in mammalian life historystrategies, serving as an organ for the storage of food andenergy, as a source of heat and water and as thermal insulation.The food and energy storage roles are especially important inallowing the animals to survive food shortages and stressesassociated with competition for mates, territorial defense,gestation and lactation, and to accomplish migrations. The composition,cellularity and anatomical site of adipose depots in a mammalcan influence both the amount of fat stored and its availabilityand usefulness in any given situation. The fatty acids and complexlipids in adipose tissue, blood vessels, nerves and brain changein response to ambient temperature and the low body temperaturesduring hibernation. Early nutrition may influence the numberof fat cells developed by a mammal, and thus affect its abilityto survive adversity. Desert species develop localized depotswhich will not interfere with temperature regulation, whileanimals in cold environments use their extensive superficialfat layers as insulation.     

Lectin-Binding Sites Involved in Paramecium primaurelia Mating Pair Formation

ABSTRACT. Mating pair formation in Paramecium primaurelia was shown to be inhibited by incubating mating-competent mating type (mt) I and mt U cells with Limulus polyphemus agglutinin (LPA) or wheat germ agglutinin (WGA). Preincubation of LPA and WGA with their specific binding-monosaccharides, N-acetylneuraminic acid (NeuAc) and N-acetylglucosamine (GlcNAc), respectively, prevented the lectin effect on pair formation. Addition either of NeuAc or GlcNAc resulted in a reversal of cell pairing inhibition by LPA or WGA, respectively. Both NeuAc and GlcNAc monosaccharides inhibited pair formation when their concentration exceeded a threshold value. The pattern of the relative distribution of NeuAc and GlcNAc molecules on the cell surface was analyzed using fluorescence resonance energy transfer techniques combined with imaging systems. Mt I1 cells showed a high lectin-binding site density localized just on the surface region engaged in conjugation. The pattern of mt I cells, consisting of a quite homogeneous lectin-binding site density spread on the cell surface, was also common to nonmating-competent cells and to immature cells. These findings suggest that in P. primaurelia pair formation involves both NeuAc and GlcNAc residues and that the development of mating-competence is related to a modification in NeuAc and GlcNAc relative distribution on the cell surface of mt 11 cells.     

Heterophylly in Ranunculus flabellaris Raf.: The Effect of Abscisic Acid

Ranunculus flabellaris Raf., the Yellow Water-Crowfoot, is aheterophyllous semi-aquatic dicotyledonous plant, showing strikingmorphological and anatomical differences between terrestrialleaves and those formed underwater. After plants are submergedin a 25 µM solution of abscisic acid, leaves are producedat a normal rate but they exhibit many of the characteristicsof terrestrial leaves. Ranunculus flabellaris Raf., Yellow Water-Crowfoot, heterophylly, abscisic acid