Relative position of trypsin banded homologous chromosomes in human (female) metaphase figures.

"Generalized distances" between centromeres were statistically analyzed (chi2 test) on 50 normal female trypsin-banded metaphase figures. This study revealed that the homologous chromosomes of the pairs 13, 17, 14, and 21 lie closer together than would be expected by a reference distribution, and this in a statistically significant way. The same relative position was demonstrated for the chromosome groups 13-14, 13-21, 14-21, 15-22, and 14-22. Evidences were collected that also showed that homologous chromosomes of the pairs 1, 19, and 20 and the chromosome groups 15-21, 13-15, and 18-20 tend to lie closer together. Giving a functional interpretation to the phenomenon of non-random distribution of chromosomes in metaphase figures, it may be suggested that the chromosomes 13, 14, and 21 are involved in the organization of the human nucleolar organizers, more frequently than the other D- and G-group chromosomes.     

Simple radio-immunoassay for the measurement of human and rat IgE levels by ammonium sulfate precipitation.

A simple assay for quantitating IgE levels has been developed based on the observation that antibody-bound IgE is insoluble in 33 percent saturated (NH-4)2-SO-4 whereas unbound IgE is not. The method has been applied to human and rat IgE. Some preliminary results on IgE levels in parasite-injected rats are presented.     

Fitness costs of worker specialization for ant societies

Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialization affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialization in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated the social organization of 102 T. longispinosus colonies, based on the behavioural responses of all 3842 workers. We find that strict specialization is disadvantageous for a colony''s annual reproduction and growth during slave raids. These fitness costs may favour generalist strategies in dynamic environments, as we also demonstrate that societies exposed to slavemakers in the field show a lower degree of specialization than those originating from slavemaker-free populations. Our findings provide an explanation for the ubiquity of generalists and highlight their importance for the flexibility and functional robustness of entire societies.     

Functional analysis of phosphorylation of the mitotic centromere-associated kinesin by Aurora B kinase in human tumor cells

Mitotic centromere-associated kinesin (MCAK) is the best characterized member of the kinesin-13 family and plays important roles in microtubule dynamics during mitosis. Its activity and subcellular localization is tightly regulated by an orchestra of mitotic kinases, such as Aurora B. It is well known that serine 196 of MCAK is the major phosphorylation site of Aurora B in Xenopus leavis extracts and that this phosphorylation regulates its catalytic activity and subcellular localization. In the current study, we have addressed the conserved phosphorylation site serine 192 in human MCAK to characterize its function in more depth in human cancer cells. Our data confirm that S192 is the major phosphorylation site of Aurora B in human MCAK and that this phosphorylation has crucial roles in regulating its catalytic activity and localization at the kinetochore/centromere region in mitosis. Interfering with this phosphorylation leads to a delayed progression through prometa- and metaphase associated with mitotic defects in chromosome alignment and segregation. We show further that MCAK is involved in directional migration and invasion of tumor cells, and interestingly, interference with the S192 phosphorylation affects this capability of MCAK. These data provide the first molecular explanation for clinical observation, where an overexpression of MCAK was associated with lymphatic invasion and lymph node metastasis in gastric and colorectal cancer patients.     

In vivo activation of quiescent B cells by anti-immunoglobulin. I. Induction of latent VH allotype production in adult rabbits by treatment with heterologous antibodies or antibody fragments

We demonstrated previously that injection of adult rabbits with homologous anti-VHa1 allotype antibody induces the appearance in serum of genetically unexpected (latent) a1 immunoglobulin (Ig) and a1-like internal images. We have now investigated the mechanism for this induction effect and have found that treatment of animals with polyclonal goat or monoclonal mouse anti-a1 antibody similarly results in production of unexpected a1 determinants. The N-terminal amino acid sequences of deblocked heavy chains showed that latent a1 Ig induced by monoclonal antibody treatment was identical to nominal a1 Ig at 18 of 19 residues, with the one amino acid difference at position 13 probably due to a single nucleotide change. Like nominal a1, these molecules expressed multiple VHa1 framework epitopes, as demonstrated by direct immunoelectron microscopic visualization of immune complexes. Whereas F(ab)'2 fragments of rabbit anti-a1 antibody retained inducing activity, F(ab) fragments were effective only when administered in an aggregated form; this result suggests that cross-linking of surface Ig receptors plays a critical role in the induction process. We conclude that all rabbits contain dormant B cells expressing germ-line-encoded latent allotypes, and that in vivo administration of anti-Ig antibody causes activation of these cells directly rather than through perturbation of an allotype regulatory network.     

Galanin-like immunoreactivity in extrinsic and intrinsic nerves to the gut of the Atlantic cod,Gadus morhua,and the effect of galanin on the smooth muscle of the gut

The presence of galanin-like immunoreactivity in nerves to the stomach of the Atlantic cod has been investigated by immunohistochemistry. The distribution of ganglion cells showing galanin-like immunoreactivity was compared with the total distribution in nerves and ganglia. Projection studies were made to determine the origin of the galanin neurons. The effect of galanin was studied in smooth muscle strip preparations of the gut wall and arteries. Galanin-like immunoreactive ganglion cells frequently occurred along the vagal branches to the stomach. Most of them projected cranially. Immunoreactive nerve fibres were present in all layers of the gut and around arterial branches on the surface of the stomach. Ligations of the vagus and splanchnic nerves produced accumulations of immunoreactive material on both sides of the ligature. Galanin produced weak contractile effects unaffected by tetrodotoxin on the gut wall and on gut arteries. It is concluded that a population of the ganglion cells along the vagus nerve in the Atlantic cod contains a galanin-like peptide. Some of these cells may be parts of autonomic parasympathetic pathways innervating the gut of the Atlantic cod, having direct excitatory effects on the smooth muscles of the gut wall and gut arteries.