Prolonged faunal turnover in earliest ants revealed by North American Cretaceous amber

All ∼14,000 extant ant species descended from the same common ancestor, which lived ∼140-120 million years ago (Ma).1,2 While modern ants began to diversify in the Cretaceous, recent fossil evidence has demonstrated that older lineages concomitantly occupied the same ancient ecosystems.3 These early-diverging ant lineages, or stem ants, left no modern descendants; however, they dominated the fossil record throughout the Cretaceous until their ultimate extinction sometime around the K-Pg boundary. Even as stem ant lineages appear to be diverse and abundant throughout the Cretaceous, the extent of their longevity in the fossil record and circumstances contributing to their extinction remain unknown.3 Here we report the youngest stem ants, preserved in ∼77 Ma Cretaceous amber from North Carolina, which illustrate unexpected morphological stability and lineage persistence in this enigmatic group, rivaling the longevity of contemporary ants. Through phylogenetic reconstruction and morphometric analyses, we find evidence that total taxic turnover in ants was not accompanied by a fundamental morphological shift, in contrast to other analogous stem extinctions such as theropod dinosaurs. While stem taxa showed broad morphological variation, high-density ant morphospace remained relatively constant through the last 100 million years, detailing a parallel, but temporally staggered, evolutionary history of modern and stem ants.

C-H-pi interactions in 1-n-butyl-3-methylimidazolium tetraphenylborate molten salt: solid and solution structures

The crystal structure of 1-n-butyl-3-methylimidazolium tetraphenylborate molten salt (1) shows C-H-pi interactions between the hydrogens of the imidazolium cation and the phenyl rings of the tetraphenylborate anion. The imidazolium ring is surrounded by three tetraphenylborate anions that are connected with the same cation by C-H-pi (phenyl rings) interactions. The nearest inter-ion interaction is found between the N-CH-N proton of the cation and the B-phenyl centroid (2.349 A) with a nearly T-shaped geometry. The inter-ionic solution structure of 1 has been investigated by the detection of inter-ionic contacts in 1H NOESY NMR spectra between the protons of the cation and the anion. The 1H-NMR spectra of molten salt 1 is almost independent of its concentration in [D6]DMSO solution, the imidazolium proton chemical shifts are in the expected region and there are no observable NOE effects between the protons of the cation with those of the anion, indicating that 1 behaves in [D6]DMSO as a solvent-separated ion pair. In CDCl3 the 1H-NMR spectra of 1 are concentration dependent and all the imidazolium protons are shielded as compared with those observed in [D6]DMSO. Moreover, the 1H NOESY NMR spectra show all the peaks affected by the interaction between the protons of the imidazolium cation and those of the anion, indicating that in CDCl3 1 possesses a contact ion pair structure. The NCHN proton of the cation exhibits the greatest shielding (up to -4.5 ppm). an indication of the existence of C-H-pi interactions, even in solution. The calculated distance of this proton to the phenyl centroid is 2.3 A for a C-H -pi angle of 180 degrees. The apparent volumes for the cation and anion, calculated from the measured 13C-NMR relaxation times, increase from 38 and 140 A3 in [D6]DMSO to 360 and 600 A3 in CDCl3, respectively; this indicates the formation of floating aggregates of the type (1)(n) in CDCl3 via weak hydrogen bonds, with increasing concentration.

Papillary squamous cell carcinomas of the upper aerodigestive tract: a clinicopathologic and molecular study

BACKGROUND

The limited studies and the small number of published cases of papillary squamous cell carcinoma have precluded accurate assessment of the biologic characteristics of this lesion.

METHODS

Thirty-eight of the carcinomas were studied. In-situ hybridization and polymerase chain reaction were performed to detect human papilloma virus (HPV) and p53 expression.

RESULTS

HPV was found in 4 of 14 assessable carcinomas by in-situ hybridization and in 5 of 14 by polymerase chain reaction. The most frequently identified HPVs were HPVs in 6/11 and 16/18 patients. In general, a reciprocal relationship was found between p53 and HPV prevalence. The most lethal site for this tumor was the sinonasal tract, whereas patients with papillary squamous cell carcinomas of the larynx had the best outlook. Eleven of 25 (44%) assessable patients died of disease (mean time interval, 2 year).

CONCLUSIONS

Papillary squamous cell carcinoma of the upper aerodigestive tract is a distinct variant of squamous cell carcinoma. As such and because of its putative association with HPV, papillary squamous cell carcinoma could be an informative model for defining how viral oncogenes cooperate with other factors in genomic instability, carcinogenesis, and tumor development.

Hybrid carcinomas of salivary glands. Report of 4 cases and review of the literature

OBJECTIVE

To report 4 cases of hybrid carcinoma and to review the literature on these rare neoplasms of the salivary gland.

METHODS

Hematoxylin-eosin-stained, formalin-fixed, paraffin-embedded tissue sections from 3 parotid tumors and 1 palate tumor were examined.

RESULTS

The cases were classified as adenoid cystic and mucoepidermoid carcinoma, adenoid cystic and epithelial-myoepithelial carcinoma, epithelial-myoepithelial and salivary duct carcinoma, and adenoid cystic and salivary duct carcinoma. All patients were men, 28 to 71 years old; 3 patients presented with parotid mass, and 1 patient presented with palatal mass. One patient presented with facial nerve paralysis and pain. The soft palatal tumor was a slowly growing mass with maxillary sinus involvement at the time of the diagnosis. All patients were treated with surgery and radiotherapy.

CONCLUSIONS

Correct identification of 2 or more neoplastic entities will help assess the aggressiveness and metastatic potential of the tumor and influence the clinical course and treatment.

Don't confuse dental soft tissues with odontogenic tumors

Surgical pathologists are cautioned against the misinterpretation of immature dental tissues (dental papillae and follicles) and dental pulp as odontogenic tumors, especially odontogenic myxomas and fibromas. The close histologic similarity of the immature tissues to tumors may require a clinical-radiologic correlation with the histopathologic specimen in order to distinguish the locally aggressive tumors from innocuous dental tissues.

Nonneoplastic vascular lesions of the middle ear

Nonneoplastic vascular lesions in the middle ear may be arterial or venous. For the former, ectopic location of the internal carotid artery is the most common; a high jugular bulb is the most common venous abnormality. Both may be clinically misdiagnosed without radiographic studies and, in the event, lead to disaster.

Tumefactive fibroinflammatory lesions of the head and neck

Tumefactive fibroinflammatory lesions of the head and neck are idiopathic, histologically benign, tumor-forming lesions that clinically stimulate malignancies. Their histopathologic appearance is nearly identical to that of fibrosclerotic lesions of the mediastinum and retroperitoneum and Riedel's thyroiditis, and in some cases, a congeneric (periarteritis) origin is postulated. There is no optimum treatment, and recurrence and persistence are common. The suggested initial treatment is corticosteroid administration.