Human implicit memory for irrelevant dimension values is similar to rats' incidental memory in simultaneous discrimination tasks

Participants completed a category-learning task in which they needed to discover which of three stimulus dimensions (shape, color or size) was relevant. After meeting a learning criterion (nine of 10 consecutive correct responses), participants continued making categorization choices and response latencies associated with these trials were examined. In both Experiments 1 and 2, people responded reliably faster when correct responses matched the previous responses with respect to irrelevant dimension values. Thus, they demonstrated a form of incidental short-term memory analogous to that we previously reported in studies of rats. In Experiment 2, participants' explicit memory for irrelevant dimension values was assessed after category learning was complete. The results indicated that people were unaware of the irrelevant dimension values encountered on trials preceding surprise probe trials. This indicates that memory for the irrelevant dimension values was implicit (i.e. unconscious). The findings are discussed with respect to both human and non-human studies of hippocampus-independent memory and implicit memory.     

Modulation of cytosolic calcium signaling by protein kinase A-mediated phosphorylation of inositol 1,4,5-trisphosphate receptors

Calcium release via intracellular Ca2+ release channels is a central event underpinning the generation of numerous, often divergent physiological processes. In electrically non-excitable cells, this Ca2+ release is brought about primarily through activation of inositol 1,4,5-trisphosphate receptors and typically takes the form of calcium oscillations. It is widely believed that information is carried in the temporal and spatial characteristics of these signals. Furthermore, stimulation of individual cells with different agonists can generate Ca2+ oscillations with dramatically different spatial and temporal characteristics. Thus, mechanisms must exist for the acute regulation of Ca2+ release such that agonist-specific Ca2+ signals can be generated. One such mechanism by which Ca2+ signals can be modulated is through simultaneous activation of multiple second messenger pathways. For example, activation of both the InsP3 and cAMP pathways leads to the modulation of Ca2+ release through protein kinase A mediated phosphoregulation of the InsP3R. Indeed, each InsP3R subtype is a potential substrate for PKA, although the functional consequences of this phosphorylation are not clear. This review will focus on recent advances in our understanding of phosphoregulation of InsP3R, as well as the functional consequences of this modulation in terms of eliciting specific cellular events.     

Congenital hypotrichosis in a white-tailed deer fawn from South Dakota

On 1 October 2001, a 4-mo-old male white-tailed deer (Odocoileus virginianus) fawn was collected in Day County, South Dakota (USA), by South Dakota Department of Game, Fish and Parks personnel. The fawn had sparse hair development on the ventral thorax, the lateral caudal and caudal aspects of the rear legs, the muzzle, around the eyes, and inside the ears. Remaining skin surfaces were devoid of hair. Histologic examination revealed normal hair follicle density although follicles were empty or contained keratin debris and fragments of hair shaft. The epidermis of the fawn was mildly thickened and melanin pigment was prominent within deep layers of the epidermis. Based on histologic examination, the deer was diagnosed with congenital hypotrichosis. Although this condition has been reported in domestic species and humans, this specimen represents the first documented case of congenital hypotrichosis in a cervid.     

Germ cell apoptosis in the testes of normal stallions

Apoptosis in testicular germ cells has been demonstrated in many mammalian species. However, little is known about the stallion (Equus caballus) and rates of apoptosis during spermatogenesis. Morphological and biochemical features of apoptosis reported in other species were used to confirm that the TdT-mediated dUTP Nick end labeling (TUNEL) assay is an acceptable method for identification and quantification of apoptotic germ cells in histological tissue sections from stallion testis. Seminiferous tubules from eight stallions with normal testis size and semen quality were evaluated according to stage of seminiferous epithelium to determine the germ cell types and stages where apoptosis most commonly occurs. Spermatogonia and spermatocytes were the most common germ cell types labeled by the TUNEL assay. A low rate of round and elongated spermatids were labeled by the TUNEL assay. Mean numbers of TUNEL-positive germ cells per 100 Sertoli cell nuclei were highest in stages IV (15.5 +/- 1.0) and V (13.5 +/- 1.1) of the seminiferous epithelial cycle (P < 0.001). An intermediate level of apoptosis was detected in stage VI (P < 0.02). These stages (IV-VI) correspond to meiotic divisions of primary spermatocytes and mitotic proliferation of B1 and B2 spermatogonia. Establishing basal levels of germ cell apoptosis is a critical step towards understanding fertility and the role of apoptosis in regulating germ cell numbers during spermatogenesis.     

Identification of bacterial populations in dairy wastewaters by use of 16S rRNA gene sequences and other genetic markers

Hydraulic flush waste removal systems coupled to solid/liquid separators and circulated treatment lagoons are commonly utilized to manage the large amounts of animal waste produced on high-intensity dairy farms. Although these systems are common, little is known about the microbial populations that inhabit them or how they change as they traverse the system. Using culture-based and non-culture-based methods, we characterized the microbial community structure of manure, water from the separator pit, and water from the circulated treatment lagoon from a large dairy in the San Joaquin Valley of California. Our results show that both total bacterial numbers and bacterial diversity are highest in manure, followed by the separator pit water and the lagoon water. The most prevalent phylum in all locations was the Firmicutes (low-G+C, gram-positive bacteria). The most commonly occurring operational taxonomic unit (OTU) had a 16S rRNA gene (rDNA) sequence 96 to 99% similar to that of Clostridium lituseburense and represented approximately 6% of the manure derived sequences, 14% of the separator pit-derived sequences and 20% of the lagoon-derived sequences. Also highly prevalent was an OTU with a 16S rDNA sequence 97 to 100% similar to that of Eubacterium tenue, comprising approximately 3% of the manure-derived sequences, 6% of the separator pit-derived sequences and 9% of the lagoon-derived sequences. Taken together, these sequences represent approximately one-third of the total organisms in the lagoon waters, suggesting that they are well adapted to this environment.     

Identification of bacilysin, chlorotetaine, and iturin a produced by Bacillus sp. strain CS93 isolated from pozol, a Mexican fermented maize dough

Three antimicrobial compounds produced by Bacillus sp. strain CS93 isolated from pozol were identified by using high-performance liquid chromatography and mass spectrometry. The three compounds were iturin, bacilysin, and chlorotetaine. Production of these compounds by CS93 could account for the medicinal properties attributed to pozol.     

The filtered Fourier difference spectrum predicts psychophysical letter discrimination in the peripheral retina

We wished to devise a measure of dissimilarity (D) which could predict psychophysical discrimination performance for Snellen letter pairs in peripheral vision. Threshold size for discriminating 33 pairs of Snellen letters was measured at 30 degrees eccentricity in the nasal retina for two subjects. D was computed for each pair by performing an overlap subtraction in the spatial domain, followed by a Fast Fourier Transform on this difference image, and dividing the total power in the resultant 'difference spectrum' by the sum of the powers of the individual letter spectra. A plot of D vs. psychophysical threshold letter size gave a mean correlation of R = -0.81. When D was calculated for letters that were low-pass filtered at different cut-off frequencies, the correlation with psychophysical performance was greatest when cut-off was between 1.25-1.9 cycles/letter (R = -0.85). Conversely, when the difference spectrum was high-pass filtered at different cut-off frequencies, the correlation decreased continuously as the cut-off increased. These results imply that the band of frequencies between zero and 1.25 cycles/letter are most important for letter discrimination in peripheral vision.