Structural differences between the repertoires of mouse and human germline genes and their evolutionary implications

 Although human and mouse antibodies are similar when one considers their diversification strategies, they differ in the extent to which kappa and lambda light chains are present in their respective variable light chain repertoires. While the Igk-V germline genes are preponderant in mice (95% or more), they comprise only 60% in humans. This may account for differences in the structural repertoire encoded in the Igk-V germline genes of these species. However, this subject has not been properly investigated, partially because a systematic structural characterization of the mouse Igk-V germline genes has not been undertaken. In the present study we compiled all available information on mouse Igk-V germline genes to characterize their structural repertoire. As expected, comparison with the structural repertoire of human Igk-V germline genes indicates differences. The most interesting is that the mouse Igk-V germline gene repertoire is more diverse in structural terms than its human counterpart: the mouse encodes seven canonical structure classes (combination of canonical structures in L1 and L3). In contrast, the human encodes only four. Analysis of the evolutionary relationships of human and mouse Igk-V germline genes led us to propose that the difference reflects a strategy of mice to compensate for the small lambda chain contribution to the repertoire of their variable light chains. Received: 1 June 1997 / Revised: 6 October 1997     

An improved model of association for VH-VL immunoglobulin domains: asymmetries between VH and VL in the packing of some interface residues

The antibody-binding site is formed as a result of the association between VH and VL domains. Several studies have shown that this association plays an important role in the mechanism of antigen-antibody interaction (Stanfield et al. Structure 1: 83-93, 1993). Considering this, we propose that variations in the VH-VL association are part of the diversification strategy of the antibody repertoires. Previously, a model of association for VH-VL domains based on geometrical characteristics of the packing at the interface was developed by Chothia et al. (J. Mol. Biol. 186: 61-663, 1985). This model includes a common association form for antibodies and a three-layer structure for the interface. In the present work, a complementary model is introduced to account for the general geometrical restrictions of the VH-VL interface, and particular arrangements related to the chemical properties or the side-chain orientations of participating residues. Groups of residues assume common side-chain orientations, which are apparently related to particular functions of different interface zones. Analyses of amino acid usage and network are in agreement with the side-chain orientation patterns. Based on these observations, a three-zone model has evolved to illuminate geometrical and functional restrictions acting over the VH-VL interface. Additionally, this study has revealed the asymmetrical relationships between VH and VL residues important for the association of the two domains.     

Coexistence of Two Distinct Copies of Naphthalene Degradation Genes in Pseudomonas Strains Isolated from the Western Mediterranean Region

We analyzed the occurrence of the naphthalene degradation upper-pathway (nah) genes in the western Mediterranean region. The amplification, restriction, and sequence analysis of internal fragments for several nah genes (nahAc, nahB, nahC, and nahE) from naphthalene-degrading strains isolated from this geographical area proved the coexistence of two distinct sets of nah genes.     

Protein kinase D1 inhibition interferes with mitosis progression

Protein kinase D1 (PKD1) plays a vital role in signal transduction, cell proliferation, membrane trafficking, and cancer; however, the majority of the studies up to date had centered primarily on PKD1 functions in interphase, very little is known about its role during cell division. We previously demonstrated that during mitosis PKD1 is activated and associated with centrosomes, spindles, and midbodies. However, these observations did not address whether PKD1 was associated with mitosis regulation. Accordingly, we used rapidly acting PKD-specific inhibitors to examine the contribution of PKD1 the sequence of events in mitosis. We found that although PKD1 overexpression did not affect mitosis progression, suppression of its catalytic activity by two structurally unrelated inhibitors (kb NB 142-70 and CRT 0066101) induced a significant delay in metaphase to anaphase transition time. PKD1 inhibition during mitosis also produced the appearance of abnormal spindles, defects in chromosome alignment, and segregation as well as apoptosis. Thus, these observations indicate that PKD1 activity is associated with mitosis regulation.     

Recombinant Newcastle Disease Virus as a Vaccine Vector

A complete cDNA clone of the Newcastle disease virus (NDV) vaccine strain Hitchner B1 was constructed, and infectious recombinant virus expressing an influenza virus hemagglutinin was generated by reverse genetics. The rescued virus induces a strong humoral antibody response against influenza virus and provides complete protection against a lethal dose of influenza virus challenge in mice, demonstrating the potential of recombinant NDV as a vaccine vector.     

Antler mineral composition of Iberian red deer <Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis> is related to mineral profile of diet

Previous studies have suggested that antlers are costly bone structures whose mineral composition may change depending on physiological and other factors. This study examined whether nutrition variation associated with deer management influences antler mineral composition and structural characteristics of whole antler. Mineral distribution and bone structure were examined in antlers from two groups of adult Iberian red deer Cervus elaphus hispanicus Hilzheimer, 1909. They were kept under different feeding regimes at an experimental deer farm and a game estate in southeastern Spain. Protein and mineral contents differed between the diet of captive deer and that of deer in the wild. Significant differences were found for Na, Mg, K and protein. Antler composition seems to reflect the diet, as antlers of deer differed in protein, Na, Mg and K, but not in total mineral content, Ca, Fe or Zn. Thus, management conditions related to nutrition are reflected on antler composition.     

A new record and an evaluation of the phylogenetic relationships of Abrothrix olivaceus markhami (Rodentia: Sigmodontinae)

Recent phylogenetic studies of the subfamily of cricetid rodents (Sigmodntinae) have validated the taxonomic classification at the tribal level of the Andean Clade. It is possible that some endemic species from Patagonian South America are part of this new tribe, but previous studies have not evaluated this hypothesis due to the difficulty of obtaining samples. In this study, we evaluate the phylogenetic relationships of Akodon markhami (Pine, 1973), a species endemic to the Chilean Patagonia, using individuals recently captured at the type locality of this taxon. Our results indicate that this form of Akodon corresponds to a subspecies of Abrothrix olivaceus, and should be incorporated into the Andean Clade as a geographic race of this widely distributed species on the South American continent. Based on a molecular clock calibration, we dated the origin of this geographic race during the last glacial cycles of the Quaternary, as the result of a vicariant process.     

Plant zonation at salt marshes of the endangered cordgrass <Emphasis Type="Italic">Spartina maritima</Emphasis> invaded by <Emphasis Type="Italic">Spartina densiflora</Emphasis>

The South American cordgrass Spartina densiflora is invading European salt marshes getting into contact with the indigenous and endangered low-marsh dominant, Spartina maritima. This work describes the evolution of the plant zonation during 7 years in a marsh of S. maritima invaded by S. densiflora. S. maritima appeared throughout the whole intertidal gradient from 1.72 to 3.33 m over Spanish Hydrographic Zero (SHZ), showing its higher biomasses and shoot densities at low elevations. In contrast, S. densiflora only invaded upper areas (>+2.59 m SHZ) at the centre of circular tussocks of S. maritima. Above-ground biomass of S. maritima dropped drastically at maximum occupation of space by the alien, and its shoot density and above-ground biomass decreased at S. densiflora zone during the study. The competitive potential of S. densiflora was reflected in high above- and below-ground biomass and shoot densities, accompanied by elevated wrack accumulation and the absence of other marsh plants presented together with S. maritima from areas dominated by S. densiflora. S. densiflora altered the native vegetational zonation pattern through the invasion of the centre of S. maritima tussocks; however, the alien invasion may be limited by the presence of the autochthonous cordgrass at lower elevations. Handling editor: Luis Mauricio Bini