Developmental and dominance-associated differences in mushroom body structure in the paper wasp Mischocyttarus mastigophorus

Primitively eusocial paper wasps exhibit considerable plasticity in their division of labor. Dominance interactions among nest mates play a strong role in determining the task performance patterns of adult females. We asked whether dominance status and task performance differences were associated with the development of subregions of the mushroom bodies (MB) of female Mischocyttarus mastigophorus queens and workers. We found that the MB calycal neuropils were better developed (relative to the Kenyon cell body layer) in the dominant females that spent more time on the nest. Increased MB calyx development was more strongly associated with social dominance than with high rates of foraging. The MB of queens resembled those of dominant workers. The results suggest that social interactions are particularly relevant to M. mastigophorus females' cognition. By examining the MB of newly emerged females, we also found evidence for significant age-related changes in MB structure.     

Heavy Rainfall,Sewer Overflows,and Salmonellosis in Black Skimmers (Rynchops niger)

EcoHealth - Extreme weather events, particularly heavy rainfall, are occurring at greater frequency with climate change. Although adverse human health effects from heavy rainfall are often...     

Physiological basis of reduced Al tolerance in ditelosomic lines of Chinese Spring wheat

Aluminum tolerance was assessed in the moderately Al-tolerant wheat (Triticum aestivum L.) cultivar Chinese Spring and a set of ditelosomic lines derived from Chinese Spring. Three ditelosomic lines lacking chromosome arms 4DL, 5AS and 7AS, respectively, exhibited decreased Al tolerance relative to the euploid parent Chinese Spring based on reduced root growth in Al-containing solutions. The physiological basis of the reduced Al tolerance was investigated. Measurements by inductively coupled argon plasma mass spectroscopy of root apical Al accumulation demonstrated that two of these three lines had a decreased ability to exclude Al from the root apex, the site of Al phytotoxicity. As Al-induced malate exudation has been suggested to be an important physiological mechanism of Al tolerance in wheat, this parameter was quantified and malate exudation was shown to be smaller in all three deletion lines compared with Chinese Spring. These results suggest that the decreased Al tolerance in at least two of the three ditelosomic lines is due to the loss of different genes independently influencing a single Al-tolerance mechanism, rather than to the loss of genes encoding alternative Al-tolerance mechanisms. Received: 3 July 2000 / Accepted: 9 August 2000     

Isolation and characterization of a novel DNA methyltransferase complex linking DNMT3B with components of the mitotic chromosome condensation machinery

Proper patterns of genome-wide DNA methylation, mediated by DNA methyltransferases DNMT1, -3A and -3B, are essential for embryonic development and genomic stability in mammalian cells. The de novo DNA methyltransferase DNMT3B is of particular interest because it is frequently overexpressed in tumor cells and is mutated in immunodeficiency, centromere instability and facial anomalies (ICF) syndrome. In order to gain a better understanding of DNMT3B, in terms of the targeting of its methylation activity and its role in genome stability, we biochemically purified endogenous DNMT3B from HeLa cells. DNMT3B co-purifies and interacts, both in vivo and in vitro, with several components of the condensin complex (hCAP-C, hCAP-E and hCAP-G) and KIF4A. Condensin mediates genome-wide chromosome condensation at the onset of mitosis and is critical for proper segregation of sister chromatids. KIF4A is proposed to be a motor protein carrying DNA as cargo. DNMT3B also interacts with histone deacetylase 1 (HDAC1), the co-repressor SIN3A and the ATP-dependent chromatin remodeling enzyme hSNF2H. Further more, DNMT3B co-localizes with condensin and KIF4A on condensed chromosomes throughout mitosis. These studies therefore reveal the first direct link between the machineries regulating DNA methylation and mitotic chromosome condensation in mammalian cells.     

Targeting the immune system: novel therapeutic approaches in squamous cell carcinoma of the head and neck

Despite advances in surgery, radiotherapy, and chemotherapy, the overall survival rates for patients with squamous cell carcinoma of the head and neck (SCCHN) have not changed over the last decades. Clearly, novel therapeutic strategies are needed for this cancer, which is highly immunosuppressive. Therefore, biologic therapies able to induce and/or up-regulate antitumor immune responses could represent a complementary approach to conventional treatments. Because patients with SCCHN are frequently immunocompromised due to the elimination or dysfunction of critical effector cells of the immune system, it might be necessary to restore these immune functions to allow for the generation of more effective antitumor host responses. Simultaneously, to prevent tumor escape, it might be necessary to alter attributes of the malignant cells. The present review summarizes recent advances in the field of immunotherapy of SCCHN, including techniques of nonspecific immune stimulation, the use of monoclonal antibodies, advances in adoptive immunotherapy and genetic engineering, as well as anticancer vaccines. These biologic therapies, alone or in combination with conventional treatment, are likely to develop into useful future treatment options for patients with SCCHN.     

NO and endogenous angiotensin II interact in the generation of renal sympathetic nerve activity in conscious rats

Nitric oxide (NO) appears to inhibit sympathetic tone in anesthetized rats. However, whether NO tonically inhibits sympathetic outflow, or whether endogenous angiotensin II (ANG II) promotes NO-mediated sympathoinhibition in conscious rats is unknown. To address these questions, we determined the effects of NO synthase (NOS) inhibition on renal sympathetic nerve activity (RSNA) and heart rate (HR) in conscious, unrestrained rats on normal (NS), high-(HS), and low-sodium (LS) diets, in the presence and absence of an ANG II receptor antagonist (AIIRA). When arterial pressure was kept at baseline with intravenous hydralazine, NOS inhibition with l-NAME (10 mg/kg i.v.) resulted in a profound decline in RSNA, to 42 +/- 11% of control (P < 0.01), in NS animals. This effect was not sustained, and RSNA returned to control levels by 45 min postinfusion. l-NAME also caused bradycardia, from 432 +/- 23 to 372 +/- 11 beats/min postinfusion (P < 0.01), an effect, which, in contrast, was sustained 60 min postdrug. The effects of NOS inhibition on RSNA and HR did not differ between NS, HS, and LS rats. However, when LS and HS rats were pretreated with AIIRA, the initial decrease in RSNA after l-NAME infusion was absent in the LS rats, while the response in the HS group was unchanged by AIIRA. These findings indicate that, in contrast to our hypotheses, NOS activity provides a stimulatory input to RSNA in conscious rats, and that in LS animals, but not HS animals, this sympathoexcitatory effect of NO is dependent on the action of endogenous ANG II.