The Effects of Sub-Regional Climate Velocity on the Distribution and Spatial Extent of Marine Species Assemblages

Many studies illustrate variable patterns in individual species distribution shifts in response to changing temperature. However, an assemblage, a group of species that shares a common environmental niche, will likely exhibit similar responses to climate changes, and these community-level responses may have significant implications for ecosystem function. Therefore, we examine the relationship between observed shifts of species in assemblages and regional climate velocity (i.e., the rate and direction of change of temperature isotherms). The assemblages are defined in two sub-regions of the U.S. Northeast Shelf that have heterogeneous oceanography and bathymetry using four decades of bottom trawl survey data and we explore temporal changes in distribution, spatial range extent, thermal habitat area, and biomass, within assemblages. These sub-regional analyses allow the dissection of the relative roles of regional climate velocity and local physiography in shaping observed distribution shifts. We find that assemblages of species associated with shallower, warmer waters tend to shift west-southwest and to shallower waters over time, possibly towards cooler temperatures in the semi-enclosed Gulf of Maine, while species assemblages associated with relatively cooler and deeper waters shift deeper, but with little latitudinal change. Conversely, species assemblages associated with warmer and shallower water on the broad, shallow continental shelf from the Mid-Atlantic Bight to Georges Bank shift strongly northeast along latitudinal gradients with little change in depth. Shifts in depth among the southern species associated with deeper and cooler waters are more variable, although predominantly shifts are toward deeper waters. In addition, spatial expansion and contraction of species assemblages in each region corresponds to the area of suitable thermal habitat, but is inversely related to assemblage biomass. This suggests that assemblage distribution shifts in conjunction with expansion or contraction of thermal habitat acts to compress or stretch marine species assemblages, which may respectively amplify or dilute species interactions to an extent that is rarely considered. Overall, regional differences in climate change effects on the movement and extent of species assemblages hold important implications for management, mitigation, and adaptation on the U.S. Northeast Shelf.     

Genetic and environmental variation in anther,pollen and pistil dimensions in sesame

Measurements of anther (length, width, depth), pollen grain (percent fertility, polar diameter, equatorial diameter, polar diameter/equatorial diameter ratio, volume) and pistil (stigma length, style length, ovary length, total pistil length, stigma width, style width, ovary width) were taken on 12 diverse sesame (Sesamum indicum L.) genotypes on each of four collection dates in 1994. Highly significant differences among genotype means were obtained for all characters except polar diameter. Highly significant differences among environment (collection date) means were found for ten of the 15 characters measured. Highly significant genotype x environment interactions were obtained for all characters except anther length. For the anther characters measured, relatively high repeatability values were found, ranging from 99.8% for length to 87.6% for depth. For the pollen grain characters measured, the repeatability values ranged from 67.6% for percent fertility to 23.1% for polar diameter. For the pistil characters measured, the repeatability values ranged from 94.0% for style width to 49.6% for total pistil length. These results indicate that genotype and environment influence anther, pollen grain and pistil characters. Variation in some of these morphological aspects could influence the consistency and interpretation of male transmission studies on both the applied and evolutionary levels.     

Structural requirements for binding to the sugar-transport system of the human erythrocyte

The structural requirements for binding to the glucose/sorbose-transport system in the human erythrocyte were explored by measuring the inhibition constants, K(i), for specifically substituted analogues of d-glucose when l-sorbose was the penetrating sugar. Derivatives in which a hydroxyl group in the d-gluco configuration was inverted, or replaced by a hydrogen atom, at C-1, C-2, C-3, C-4 or C-6 of the d-glucose molecule, all bound to the carrier, confirming that no single hydroxyl group is essential for binding to the carrier. The binding and transport of 1-deoxy-d-glucose confirmed that the sugars bind in the pyranose form. The relative inhibition constants of d-glucose and its deoxy, epimeric and fluorinated analogues are consistent with the combination of beta-d-glucopyranose with the carrier by hydrogen bonds at C-1, C-3, probably C-4, and possibly C-6 of the sugar. Both polar and non-polar substituents at C-6 enhance the affinity of d-glucose derivatives relative to d-xylose, and d-galactose derivatives relative to l-arabinose, and it is suggested that the carrier region around C-6 of the sugar may contain both hydrophobic and polar binding groups. The spatial requirements at C-1, C-2, C-3, C-4 and C-6 were explored by comparing the relative binding of d-glucose and its halogeno and O-alkyl substituents. The carrier protein closely approaches the sugar except at C-3 in the d-gluco configuration, C-4 and C-6. d-Glucal was a good inhibitor, showing that a strict chair form is not essential for binding. 3-O-(2',3'-Epoxypropyl)-d-glucose, a potential substrate-directed alkylating agent, bound to the carrier, but did not inactivate it.     

Serotonergic component of SCH 23390: in vitro and in vivo binding analyses

A series of benzazepines related to SCH 23390 were tested for binding to the 5HT-2 receptor. The compounds tested inhibited the binding of 3H-ketanserin with KI values generally greater than those observed for the D-1 receptor, but less than those for the D-2 receptor. When this serotonergic activity was correlated to the D-1 activity, the resulting coefficient was 0.84, indicating a strong correlation between the two activities. Conversely, the 5HT-2 activity did not show a good correlation with the D-2 activity. To further test the significance of the 5HT-2 binding of the SCH 23390, in vivo binding studies were performed using 125I-SCH 38840 in the frontal cortex, an area containing both D-1 and 5HT-2 receptors. The in vivo binding of 125I-SCH 38840 to frontal cortex exhibited peak levels one hour following subcutaneous administration, similar to the time course previously observed in striatum. The binding was both D-1 and tissue specific. Competition studies with selected standards demonstrated that inhibition of the binding to frontal cortex, in contrast to the inhibition observed in the striatum, exhibited a Hill coefficient less than unity, implying interaction at more than one receptor subtype. When SCH 23390 and ketanserin were administered simultaneously, the inhibition of the in vivo binding of 125I-SCH 38840 to striatum was not different than that observed with SCH 23390, alone. However, the inhibition of binding to frontal cortex was significantly greater than that demonstrated with either SCH 23390 or ketanserin, alone, suggesting that 125I-SCH 38840 was binding to both D-1 and 5HT-2 receptors, in vivo.     

Two-dimensional gel studies of genetic variation in the plasma proteins of Amerindians and Japanese

Summary Genetic variation has been studied in plasma samples from 107 Amerindian children and their parents, and 110 Japanese children and their parents by means of two-dimensional polyacrylamide gel electrophoresis. Twenty-three polypeptides were scored; the identity of nine of these is at present still unknown. Genetic variation was encountered in 11 of these polypeptides. We have previously reported that the index of heterozygosity was 6.2±0.7% for 20 randomly selected, silver stained polypeptides scored for genetic variation in Caucasoids (Rosenblum et al. 1983b). For technical reasons only 11 of these 20 polypeptides could be routinely scored in preparations from the Amerindian samples. For these 11 polypeptides, the indices of heterozygosity in the three populations were: Amerindians, 4.5±0.6%; Japanese, 5.7±0.7%; Caucasoids, 8.0±1.1%. Even with these relatively small numbers some striking ethnic differences as regards individual polypeptides are apparent.     

Synergistic Cooperation between Two ClpB Isoforms in Aggregate Reactivation

Bacterial AAA⁺ ATPase ClpB cooperates with DnaK during reactivation of aggregated proteins. The ClpB-mediated disaggregation is linked to translocation of polypeptides through the channel in the oligomeric ClpB. Two isoforms of ClpB are produced in vivo: the full-length ClpB95 and ClpB80, which does not contain the substrate-interacting N-terminal domain. The biological role of the truncated isoform ClpB80 is unknown. We found that resolubilization of aggregated proteins in Escherichia coli after heat shock and reactivation of aggregated proteins in vitro and in vivo occurred at higher rates in the presence of ClpB95 with ClpB80 than with ClpB95 or ClpB80 alone. Combined amounts of ClpB95 and ClpB80 bound to aggregated substrates were similar to the amounts of either ClpB95 or ClpB80 bound to the substrates in the absence of another isoform. The ATP hydrolysis rate of ClpB95 with ClpB80, which is linked to the rate of substrate translocation, was not higher than the rates measured for the isolated ClpB95 or ClpB80. We postulate that a reaction step that takes place after substrate binding to ClpB and precedes substrate translocation is rate-limiting during aggregate reactivation, and its efficiency is enhanced in the presence of both ClpB isoforms. Moreover, we found that ClpB95 and ClpB80 form hetero-oligomers, which are similar in size to the homo-oligomers of ClpB95 or ClpB80. Thus, the mechanism of functional cooperation of the two isoforms of ClpB may be linked to their heteroassociation. Our results suggest that the functionality of other AAA⁺ ATPases may be also optimized by interaction and synergistic cooperation of their isoforms.     

Chlornaphazine and chlorambucil induce dominant lethal mutations in male mice

Two antineoplastic agents, chlornaphazine (CN) and chlorambucil (CHL), were tested for the induction of dominant lethal mutations in male mice. Both compounds are nitrogen mustard derivatives and have been shown to be genotoxic in a variety of organisms. CN was administered intraperitoneally to DBA/2J male mice at a dosage of 0, 500, 1000, or 1500 mg/kg body weight (bw). Immediately following treatment, each male was mated at 4-day intervals to two virgin C57BL/6J females. CHL was administered intraperitoneally to C3H/HeJ and DBA/2J males at a dosage of 0, 2.5, or 5.0 mg/kg bw. These males were mated at weekly intervals to two virgin T-stock females. CN and CHL clearly induced dominant lethal mutations. CN induced dominant lethal effects in all post-meiotic germ-cell stages of treated DBA males, with a clear dose-response relationship. The results with CHL-treated DBA males indicated that all post-meiotic germ-cell stages, except late-spermatids, were affected by CHL treatment, while in C3H males, CHL induced dominant lethal effects in all post-meiotic germ-cell stages. A dose-response relationship was also observed with CHL in C3H male mice. In the present experiments, regardless of the agent or the mouse strain used, spermatids appeared to be the germ-cell stage most sensitive to dominant lethal induction.     

Characterization of human immunodeficiency virus Gag-specific gamma interferon-expressing cells following protective mucosal immunization with alphavirus replicon particles

A safe, replication-defective viral vector that can induce mucosal and systemic immune responses and confer protection against many infectious pathogens, such as human immunodeficiency virus type 1 (HIV-1), may be an ideal vaccine platform. Accordingly, we have generated and tested alphavirus replicon particles encoding HIV-1 Gag from Sindbis virus (SIN-Gag) and Venezuelan equine encephalitis virus (VEE-Gag), as well as chimeras between the two (VEE/SIN-Gag). Following intramuscular (i.m.), intranasal (i.n.), or intravaginal (IVAG) immunization with VEE/SIN-Gag and an IVAG challenge with vaccinia virus encoding HIV Gag (VV-Gag), a larger number of Gag-specific CD8+ intracellular gamma interferon-expressing cells (iIFNEC) were detected in iliac lymph nodes (ILN), which drain the vaginal/uterine mucosa (VUM), than were observed after immunizations with SIN-Gag. Moreover, a single i.n. or IVAG immunization with VEE/SIN-Gag induced a larger number of cells expressing HIV Gag in ILN, and immunizations with VEE/SIN-Gag through any route induced better protective responses than immunizations with SIN-Gag. In VUM, a larger percentage of iIFNEC expressed alpha4beta7 or alpha(Ebeta)7 integrin than expressed CD62L integrin. However, in spleens (SP), a larger percentage of iIFNEC expressed alpha4beta7 or CD62L than expressed alpha(Ebeta)7. Moreover, a larger percentage of iIFNEC expressed the chemokine receptor CCR5 in VUM and ILN than in SP. These results demonstrate a better induction of cellular and protective responses following immunizations with VEE/SIN-Gag than that following immunizations with SIN-Gag and also indicate a differential expression of homing and chemokine receptors on iIFNEC in mucosal effector and inductive sites versus systemic lymphoid tissues.