A clarification of two congeners,Pseudodiaptomus lobipes and P. binghami (Calanoida,Pseudodiaptomidae) from India,with description of P. mixtus sp.n. from Bangladesh

Two closely related and often confused species of Pseudodiaptomus from the Lobus-species group, P. lobipes and P. binghami are redescribed from various locations along the east coast of India. These species predominately occur in freshwater though they can survive temporary periods of increased salinity. The distinctive features of the species are found on: female caudal ramal setae, female and male urosome 1–2 spinulation patterns, and fifth legs. A new species P. mixtus from Bangladesh is described.     

Amphetamine Promotes Neostriatal Ascorbate Release via a Nigro-Thalamo-Cortico-Neostriatal Loop

Abstract: In the neostriatum, amphetamine and other dopamine agonists elevate the extracellular level of ascorbate, which is known to modulate neostriatal function. Although both D₁ and D₂ receptors have been linked to neostriatal ascorbate release, ample evidence suggests it is controlled by areas outside the neostriatum. The present series of experiments used selective lesions and intracerebral drug infusions to probe the involvement of the ventromedial thalamus and substantia nigra pars reticulata. Our results implicate both of these sites in amphetamine-induced increases in the release of neostriatal ascorbate. Thus, whereas unilateral electrolytic lesions of the substantia nigra pars reticulata completely abolished the ability of systemic amphetamine (2.5 mg/kg) to increase extracellular ascorbate in ipsilateral neostriatum, intranigral infusions of this drug (10 and 30 µg/µl) elevated neostriatal ascorbate release. This infusion effect, moreover, was blocked by electrolytic lesions of the ipsilateral ventromedial thalamus, which receives input from the substantia nigra pars reticulata and projects to the cerebral cortex. These results, combined with previous evidence implicating cortical projections to neostriatum as the source of extracellular ascorbate, suggest that neostriatal ascorbate release is regulated, at least in part, by a nigro-thalamo-cortico-neostriatal pathway.     

A single amino acid change determines persistence of a chimeric Theiler's virus.

The DA strain of Theiler's virus persists in the central nervous system of mice and causes chronic inflammation and demyelination. On the other hand, the GDVII strain causes an acute encephalitis and does not persist in surviving animals. Series of recombinants between infectious cDNA clones of the genomes of DA and GDVII viruses have been constructed. The analysis of the phenotypes of the recombinant viruses has shown that determinants of persistence and demyelination are present in the capsid proteins of DA virus. Chimeric viruses constructed by the different research groups gave consistent results, with one exception. Chimeras GD1B-2A/DAFL3 and GD1B-2C/DAFL3, which contain part of capsid protein VP2, capsid proteins VP3 and VP1, and different portions of P2 of GDVII in a DA background, were able to persist and cause demyelination. Chimera R4, whose genetic map is identical to that of GD1B-2A/DAFL3, was not. After exchanging the viral chimeras between laboratories and verifying each other's observations, new chimeras were generated in order to explain this difference. Here we report that the discrepancy can be attributed to a single amino acid difference in the sequence of the capsid protein VP2 of the two parental DA strains. DAFL3 (University of Chicago) and the chimeras derived from it, GD1B-2A/DAFL3 and GD1B-2C/DAFL3, contain a Lys at position 141, while TMDA (Institut Pasteur) and R4, the chimera derived from it, contain an Asn in that position. This amino acid is located at the tip of the EF loop, on the rim of the depression spanning the twofold axis of the capsid. These results show that a single amino acid change can confer the ability to persist and demyelinate to a chimeric Theiler's virus, and they pinpoint a region of the viral capsid that is important for this phenotype.     

Isolation of infectious pancreatic necrosis virus (serotype Ab) from diverse species of estuarine fish

Two significant fish kills occurred in the Pamlico River estuary (North Carolina, USA), one in December 1981 and January 1982, and the other in June 1982. The first involved only the southern flounder(Paralichthys lethostigma). Histopathologic examination of morbid and moribund flounder revealed extensive sloughing and necrosis of the mucosa of the pyloric caeca and intestine, and inflammation of the submucosa of the pyloric caeca. Brain and internal organ homogenates from morbid and moribund flounder were assayed on CHSE-214 cells, and a virus was isolated. Virus titers ranged from8.4 · 10² to 6.3 · 10⁷ TCID₅₀ per gram of tissue. Cross-plaque neutralization assays indicated that the southern flounder virus was infectious pancreatic necrosis virus serotype Ab. Immersion challenge showed the isolate is only slightly virulent for fry of brook trout(Salvelinus fontinalis). The second fish kill involved the southern flounder and six other species: hogchoker(Trinectes maculatus), Atlantic silverside(Menidia menidia), spot(Leiostomus xanthurus), Atlantic croaker(Micropogon undulatus), silver perch(Bairdiella chrysura), and striped mullet(Mugil cephalus). Virus was isolated from southern founder, hogchoker, Atlantic silverside, and spot. Neutralization assays indicated that the four isolates were nearly identical; however, the diversity of species affected suggests that the virus might not have been the specific cause of mortality.     

Analysis of the effect of transplantation on morphometric and meristic characters in lake populations of the rainbow smelt,Osmerus mordax (Mitchill)

Synopsis Results of experimental transfer of rainbow smelt into lakes reclaimed by rotenone around 1960 in Maine were originally interpreted to cast doubt on the previously widely accepted hypothesis that there were two hereditarily different forms of rainbow smelt, one large and one small. Study of more recent data from some of the transplanted populations and reanalysis of the original data suggests different conclusions. The initial effect of introductions into a reclaimed lake may be accelerated and/or more prolonged growth which exceeds even interlake differences. This initial phase, however, is followed by a second phase, when the population reaches equilibrium and these effects subside. Data from phase two of the Little Concord-Shagg and Cold Stream-Coleback Lake transfers showed that the growth characteristics of the transplanted populations returned to those of the parental populations. Large differences in growth patterns were thus found only in the initial phase of the introduction. Meristic characters were little affected by transplanting.Analysis of large specimens derived from a postulated second unofficial introduction into Coleback Lake showed that they also differed significantly, having both higher gill raker and vertebral counts than the smaller smelt. This was of interest as smelt vertebral and gill raker counts usually are inversely related; hence we do not equate these for the moment with the large form of smelt known elsewhere.It is concluded that the initial interpretation of transfer experiments be delayed until conditions approaching equilibrium can be expected to exist. Further, our analysis of more recent lake transfer data has shown nothing to refute the hypothesis that there are at least two hereditarily different forms of smelt.     

Theiler's virus infection induces a specific cytotoxic T lymphocyte response

Theiler's virus, a murine picornavirus, persists in the central nervous system of susceptible mouse strains and causes chronic inflammation and primary demyelination. One of the current hypotheses is that demyelination is, at least in part, mediated by virus-specific cytotoxic T lymphocytes (CTL). However, it is generally assumed that picornaviruses do not induce CTL. In point of fact, their existence has only been demonstrated for Coxsackievirus B-3. To determine whether Theiler's virus induces a CTL response, we generated a murine mastocytoma cell line stably transfected with the coding region of the genome of Theiler's virus strain DA. Using these cells as targets we showed that infected DBA/2 mice, a susceptible strain, produce cytotoxic T lymphocytes. The cytotoxic activity was Theiler's-virus specific. It was for the most part mediated by CD8+ T lymphocytes and H-2 restricted. This is the first demonstration that a specific CTL response is generated during Theiler's virus infection.